GCT Semiconductor Holding (GCTS) S-1 21 May 24 IPO registration Financial data

Document and Entity Information

Document and Entity Information	3 Months Ended
	Mar. 31, 2024
Document and Entity Information
Document Type	S-1
Entity Registrant Name	GCT Semiconductor Holding, Inc.
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Central Index Key	0001851961
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets $ in Thousands	Mar. 31, 2024 USD ($)
Current assets:
Cash and cash equivalents	$ 16,122
Accounts receivable, net	5,103
Inventory	1,784
Contract assets	4,313
Prepaid expenses and other current assets	5,466
Total current assets	32,788
Property and equipment, net	644
Operating lease right-of-use assets	1,343
Intangibles, net	187
Other assets	857
Total assets	35,819
Current liabilities:
Accounts payable	1,242
Contract liabilities	35
Accrued and other current liabilities	25,152
Borrowings	39,840
Convertible promissory notes, current	5,645
Operating lease liabilities, current	679
Total current liabilities	72,593
Convertible promissory notes, net of current	4,672
Net defined benefit liabilities	7,488
Long-term operating lease liabilities	674
Income taxes payable	2,096
Warrant liabilities	10,584
Other liabilities	72
Total liabilities	98,179
Commitments and contingencies (Note 8)
Stockholders' deficit:
Preferred stock, par value $0.0001 per share; 40,000 and 82,352 shares authorized as of March 31, 2024 and December 31, 2023, respectively; no shares issued and outstanding as of March 31, 2024 and December 31, 2023
Common stock, par value $0.0001 per share; 400,000 and 200,000 shares authorized as of March 31, 2024 and December 31, 2023, respectively; 45,833 and 24,166 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively(1)	5	[1]
Additional paid-in capital(1)	487,006
Accumulated other comprehensive loss	(474)
Accumulated deficit	(548,897)
Total stockholders' deficit	(62,360)
Total liabilities and stockholders' deficit	$ 35,819
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2024	Mar. 26, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Consolidated Balance Sheets
Preferred stock, par value	$ 0.0001		$ 0.0001
Preferred stock, shares authorized	40,000,000		82,352,000
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0
Common stock, par value per share	$ 0.0001		$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000		200,000,000	200,000,000
Common stock, shares issued	45,833,000	45,833,000	24,166,000	127,760,265
Common stock, shares outstanding	45,833,000		24,166,000	24,166,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($)		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Net revenues:
Total net revenues		$ 3,265,000	$ 3,062,000
Cost of net revenues:
Total cost of net revenues		1,312,000	1,541,000
Gross profit		1,953,000	1,521,000
Operating expenses:
Research and development		5,521,000	902,000
Sales and marketing		996,000	836,000
General and administrative		2,836,000	1,477,000
Gain on extinguishment of liability		(14,636,000)
Total operating (income) expenses		(5,283,000)	3,215,000
Income (loss) from operations		7,236,000	(1,694,000)
Interest expense		(2,082,000)	(935,000)
Other (expenses) income, net		(4,338,000)	1,286,000
Income (loss) before provision for income taxes		816,000	(1,343,000)
Provision for income taxes		59,000	50,000
Net income (loss)		757,000	(1,393,000)
Net loss attributable to common stockholders		757,000	(1,393,000)
Net income (loss), diluted		$ 757,000	$ (1,393,000)
Net income (loss) per common share - basic	[1]	$ 0.03	$ (0.06)
Net income (loss) per common share - diluted	[1]	$ 0.03	$ (0.06)
Weighted-average common shares outstanding, basic	[1]	25,468,000	23,862,000
Weighted-average shares used in computing net income (loss) per common shares - diluted	[1]	26,257,000	23,862,000
Product
Net revenues:
Total net revenues		$ 2,378,000	$ 599,000
Cost of net revenues:
Total cost of net revenues		654,000	978,000
Service
Net revenues:
Total net revenues		887,000	2,463,000
Cost of net revenues:
Total cost of net revenues		$ 658,000	$ 563,000
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Comprehensive income (loss), net of taxes:
Net income (loss)	$ 757	$ (1,393)	$ (22,469)	$ (26,412)
Foreign currency translation adjustment	1,064	674	324	1,583
Comprehensive income (loss)	$ 1,821	$ (719)	$ (22,145)	$ (24,829)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Deficit - USD ($) $ in Thousands		Common Stock Previously reported	Common Stock Revision of prior period, adjustment	Common Stock		Additional Paid-in Capital Previously reported	Additional Paid-in Capital Revision of prior period, adjustment	Additional Paid-in Capital		Accumulated Other Comprehensive Income (Loss) Previously reported	Accumulated Other Comprehensive Income (Loss)		Accumulated Deficit Previously reported	Accumulated Deficit		Previously reported	Total
Balance as at beginning at Dec. 31, 2021																	$ 382,288
Balance as at beginning (in shares) at Dec. 31, 2021																	73,259,663
Increase (Decrease) in Redeemable Convertible Preferred Stock [Roll Forward]
Accretion of Series G redeemable convertible preferred stock to redemption amount																	$ 2,237
Conversion of redeemable convertible preferred stock to common stock																	$ (384,525)
Conversion of redeemable convertible preferred stock to common stock (in shares)																	(73,259,663)
Balance as at end (in shares) at Dec. 31, 2022	[1]			23,861,000
Balance as at beginning at Dec. 31, 2021				$ 13				$ 13,682			$ (3,445)			$ (498,536)			$ (488,286)
Balance as at beginning (in shares) at Dec. 31, 2021				13,183,259
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of Series G redeemable convertible preferred stock to redemption amount														(2,237)			(2,237)
Conversion of redeemable convertible preferred stock to common stock				$ 74				384,451									384,525
Conversion of redeemable convertible preferred stock to common stock (in shares)				73,203,888
Common stock dividends issued to Series C and Series G redeemable convertible preferred stock				$ 29				(29)
Common stock dividends issued to Series C and Series G redeemable convertible preferred stock (in shares)				28,685,582
Issuance of common stock upon exercise of stock options				$ 2				49									51
Issuance of common stock upon exercise of stock options (in shares)				2,459,014
Issuance of common stock from conversion of convertible promissory notes and accrued interest				$ 10				35,820									35,830
Issuance of common stock from conversion of convertible promissory notes and accrued interest (in shares)				10,228,522
Stock-based compensation								17									17
Foreign currency translation adjustment											1,583						1,583
Net income (loss)														(26,412)			(26,412)
Balance as at end at Dec. 31, 2022		$ 128	$ (126)	$ 2	[1]	$ 433,990	$ 126	434,116	[1]	$ (1,862)	(1,862)	[1]	$ (527,185)	(527,185)	[1]	$ (94,929)	$ (94,929)	[1]
Balance as at end (in shares) at Dec. 31, 2022		127,761,000	(103,900,000)														127,760,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options	[1]							1									$ 1
Issuance of common stock upon exercise of stock options (in shares)	[1]			5,000
Stock-based compensation	[1]							2									2
Foreign currency translation adjustment											674						674
Net income (loss)														(1,393)			(1,393)
Balance as at end at Mar. 31, 2023				$ 2				434,119			(1,188)			(528,578)			(95,645)
Balance as at end (in shares) at Mar. 31, 2023				23,866,000
Balance as at beginning (in shares) at Dec. 31, 2022	[1]			23,861,000
Balance as at beginning at Dec. 31, 2022		$ 128	$ (126)	$ 2	[1]	433,990	126	434,116	[1]	(1,862)	(1,862)	[1]	(527,185)	(527,185)	[1]	(94,929)	$ (94,929)	[1]
Balance as at beginning (in shares) at Dec. 31, 2022		127,761,000	(103,900,000)														127,760,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of Series G redeemable convertible preferred stock to redemption amount																	$ 0
Issuance of common stock upon exercise of stock options				$ 1				22									23
Issuance of common stock upon exercise of stock options (in shares)				1,130,481
Issuance of common stock from conversion of convertible promissory notes and accrued interest								72									72
Issuance of common stock from conversion of convertible promissory notes and accrued interest (in shares)				20,681
Issuance of common stock from cancellation of promissory note				55,775
Issuance of common stock from warrant exercise								1,499									1,499
Issuance of common stock from warrant exercise (in shares)				428,572
Stock-based compensation								43									43
Foreign currency translation adjustment											324						324
Net income (loss)														(22,469)			(22,469)
Balance as at end at Dec. 31, 2023		$ 129	$ (126)	$ 3	[1]	$ 435,626	$ 126	435,752	[1]	$ (1,538)	(1,538)	[1]	$ (549,654)	(549,654)	[1]	$ (115,437)	$ (115,437)	[1]
Balance as at end (in shares) at Dec. 31, 2023		129,395,774	(105,230,000)	24,166,000	[1]												24,166,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reverse recapitalization transaction, net of transaction costs and acquired liabilities				$ 2				50,031									$ 50,033
Reverse recapitalization transaction, net of transaction costs and acquired liabilities (in shares)				21,667,000
Stock-based compensation								1,223									1,223
Foreign currency translation adjustment											1,064						1,064
Net income (loss)														757			757
Balance as at end at Mar. 31, 2024				$ 5				$ 487,006			$ (474)			$ (548,897)			$ (62,360)
Balance as at end (in shares) at Mar. 31, 2024				45,833,000													45,833,000
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities:
Net income (loss)	$ 757	$ (1,393)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	206	225
Operating lease right-of-use amortization	176	168
Finance lease right-of-use amortization		4
Stock-based compensation	1,223	2
Provision for credit losses	247
Gain on extinguishment of liability	(14,636)
Change in valuation of convertible promissory notes	1,203	(549)
Change in valuation of warrant liabilities	4,626
Changes in operating assets and liabilities:
Accounts receivable	(501)	2,144
Inventory	(298)	(651)
Contract assets	(874)	(1,769)
Prepaid expenses and other current assets	(2,292)	102
Other assets	24	35
Accounts payable	(2,713)	133
Contract liabilities	(13)	(650)
Accrued and other current liabilities	(1,067)	1,048
Net defined benefit liabilities	109	186
Income tax payable	(83)
Lease liabilities	(177)	(170)
Other liabilities	(330)	(345)
Net cash used in operating activities	(14,413)	(1,480)
Investing activities:
Purchases of property and equipment		(118)
Net cash used in investing activities		(118)
Financing activities:
Proceeds from exercise of stock options		1
Proceeds from bank borrowings		582
Proceeds from issuance of convertible promissory notes	16,290
Proceeds from reverse recapitalization and PIPE Financing, net of transaction costs	17,238
Repayment of bank borrowings	(3,254)	(31)
Net cash provided by financing activities	30,274	552
Effect of exchange rate changes on cash and cash equivalents	3	(52)
Net increase (decrease) in cash and cash equivalents	15,864	(1,098)
Cash and cash equivalents at beginning of year	258	1,398
Cash and cash equivalents cash at end of year	16,122	300
Supplemental disclosure of cash flow information:
Cash paid for interest	1,183	368
Cash paid for income taxes	3	3
Cash paid for amounts included in the measurement of operating leases	192	$ 195
Issuance of common stock from conversion of convertible promissory notes and accrued interest	$ 41,209

Organization and Liquidity

Organization and Liquidity	3 Months Ended
	Mar. 31, 2024
Organization and Liquidity
Organization and Liquidity	1. Organization and Liquidity Description of Business GCT Semiconductor Holdings, Inc. (formerly known as Concord Acquisition Corp III) and its wholly owned subsidiaries (collectively “GCT”, or the “Company”) is headquartered in San Jose, California with international offices in Korea, China, Taiwan, and Japan. The Company is a fabless semiconductor company that specializes in the design, manufacturing and sale of communication semiconductors, including high-speed wireless communication technologies such as 5G/4.75G/4.5G/4G transceivers and modems, which are essential for a wide variety of industrial, B2B and consumer applications. On March 26, 2024 (the “Closing Date” or “Closing”), Concord Acquisition Corp III (“Concord III”), a Delaware corporation, consummated a series of transactions that resulted in the combination of Gibraltar Merger Sub Inc., a Delaware corporation and a wholly-owned subsidiary of Concord III (“Merger Sub”), and GCT Semiconductor, Inc. (hereinafter referred to as “Legacy GCT”), pursuant to a Business Combination Agreement, dated November 2, 2023 (as amended, the “Business Combination Agreement”), by and among Concord III, Merger Sub and Legacy GCT. Pursuant to the terms of the Business Combination Agreement, Merger Sub merged with and into Legacy GCT, with Legacy GCT surviving the merger as a wholly-owned subsidiary of Concord III (the “Business Combination”). On the Closing Date, Concord III changed its name from Concord III to “GCT Semiconductor Holding, Inc.” The Business Combination was accounted for as a reverse recapitalization with Legacy GCT being the accounting acquirer and Concord III as the acquired company for accounting purposes. Accordingly, all historical financial information presented in the unaudited condensed consolidated financial statements represent the accounts of Legacy GCT. Pursuant to the Business Combination Agreement, the shares and net loss per common share prior to the Closing have been retroactively restated as shares reflecting the exchange ratio established in the Closing of approximately 0.1868. Prior to the Business Combination, Concord III’s public shares, and public redeemable warrants, were listed on the New York Stock Exchange (“NYSE”) under the symbols “CNDB.U,” “CNDB” and “CNDB.WS,” respectively. On March 27, 2024, the Company’s common stock and public warrants began trading on the NYSE, under the symbols “GCTS” and “GCTSW,” respectively. See Note 3 for additional information. In connection with the Closing, Concord III’s Class A common stock and Class B common stock were recapitalized into a single class of common stock. Liquidity The accompanying condensed consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and liabilities and commitments in the normal course of business. Prior to March 31, 2024, the Company has incurred operating losses and negative cash flows from operating and had an accumulated deficit of $548.9 million as of March 31, 2024. The Company’s existing sources of liquidity as of March 31, 2024 include cash and cash equivalents of $16.1 million. The Company has historically funded operations primarily with issuances of capital stock and the incurrence of debt. The Company received $17.2 million in cash proceeds from the reverse recapitalization and PIPE Financing (as defined in Note 3), net of transaction costs. The Company believes the proceeds received in connection with the Business Combination and other capital resources available to the Company including sales of products and services and the

Summary of Significant Accounti

Summary of Significant Accounting Policies and Basis of Presentation	3 Months Ended
	Mar. 31, 2024
Summary of Significant Accounting Policies and Basis of Presentation
Summary of Significant Accounting Policies and Basis of Presentation	2. Summary of Significant Accounting Policies and Basis of Presentation Principles of Consolidation and Basis of Presentation The condensed consolidated financial statements and accompanying notes include the accounts of the Company and its wholly owned subsidiaries, after elimination of intercompany balances and transactions. The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the requirements of the Securities and Exchange Commission (“SEC”) for interim financial information. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the year ended December 31, 2023, which are included in the Company’s Form 8-K filed with the SEC on April 1, 2024. The information as of December 31, 2023 included in the condensed consolidated balance sheets was derived from those audited consolidated financial statements. The unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial information. The condensed consolidated results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results to be expected for the year ending December 31, 2024 or for any other future annual or interim period. Use of Estimates The preparation of the accompanying condensed consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates, and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. These judgments, estimates and assumptions are used for but not limited to revenue recognition, provision for credit losses, inventory obsolescence, recoverability of long-lived assets, certain accrued expenses, stock-based compensation, determination of fair value of the Company’s convertible promissory notes, common stock (prior to the reverse recapitalization), warrant labilities and stock options, and deferred income taxes including related valuation allowances. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates, and these differences may be material. Fair Value of Financial Instruments The carrying amount of certain financial instruments held by the Company, such as cash equivalents, accounts receivable, contract assets and liabilities, accounts payable, and accrued and other current liabilities, approximate fair value due to their short maturities. The carrying amount of the liabilities for the convertible promissory notes represents their fair value. The carrying amounts of the Company’s bank borrowings and lease liabilities approximate fair value due to the market interest rates that these obligations bear and interest rates available to the Company. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s Level 3 financial instruments consist of convertible promissory notes and warrant liabilities. These financial instruments were valued using valuation techniques that are considered to be a Level 3 fair value measurement . Risk and Uncertainties The Company is subject to certain risks and uncertainties and believes changes in any of the following areas could have a material adverse effect on the Company’s future financial position or results of operations or cash flows: new product development, including market receptivity, the ability to satisfy obligations under development agreements with major partners, litigation or claims against the Company based on intellectual property, patent, product regulation or other factors, competition from other products, general economic conditions, the ability to attract and retain qualified employees and ultimately to sustain profitable operations. The semiconductor industry is characterized by rapid technological change, competition, competitive pricing pressures and cyclical market patterns. The Company’s financial results are affected by a wide variety of factors, such as general economic conditions specific to the semiconductor industry and the Company’s particular market, the timely implementation of new products, new manufacturing process technologies and the ability to safeguard patents and intellectual property in a rapidly evolving market. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns. As a result, the Company may experience significant period-to-period fluctuations in condensed consolidated operating results due to the factors mentioned above or other factors. The Company’s revenue may be impacted by its ability to obtain adequate wafer supplies from foundries and back-end production capacity from the Company’s test and assembly subcontractors. The foundries with which the Company currently has arrangements may not be willing or able to satisfy all of the Company’s manufacturing requirements on a timely basis and/or at favorable prices. The Company is also subject to the risks of service disruptions, raw material shortages and price increases by its foundries. Such disruptions, shortages and price increases could harm the Company’s consolidated operating results. Provision for Credit Losses The provision for credit losses is based on the Company’s assessment of the collectability of its customer accounts. The Company reviews the provision for credit losses by considering certain factors such as historical experience, industry data, credit quality, age of balances and current economic conditions that may affect a customer’s ability to pay. Uncollectible receivables are written off when all efforts to collect have been exhausted and recoveries are recognized when they are recovered. The Company determined that provisions for credit losses of approximately $1.9 million and $1.6 million were necessary as of March 31, 2024 and December 31, 2023, respectively. Concentration of Credit Risk Financial instruments that potentially subject the Company to the concentration of credit risk consist of cash and cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents primarily with one financial institution located in the United States and another financial institution located in Korea where amounts deposited may exceed Federal Deposit Insurance Corporation or Korea Deposit Insurance Corporation limits. The Company’s accounts receivable balances are primarily derived from revenues earned from customers located in the United States, China, Korea, Japan and Taiwan. The Company performs ongoing credit evaluations of its customers’ and distributors’ financial condition and generally does not require collateral from its customers. The Company’s net revenue and accounts receivable are concentrated among a few significant customers, which could expose the Company to financial risk in the event of adverse developments with these customers. Four customers accounted for approximately 28 percent, 19 percent, 18 percent and 13 percent of the Company’s gross accounts receivable as of March 31, 2024. Four customers accounted for approximately 27 percent, 19 percent, 14 percent and 10 percent of the Company’s gross accounts receivable as of December 31, 2023. Two customers accounted for approximately 61 percent and 24 percent of the Company’s total net revenues for the three months ended March 31, 2024. Four customers accounted for approximately 28 percent, 28 percent, 25 percent, and 10 percent of the Company’s total net revenues for the three months ended March 31, 2023. Management closely monitors the creditworthiness and performance of these key customers and has established credit limits and terms to mitigate potential credit risks. The Company also continues to diversify its customer base and explore opportunities to reduce its reliance on a few major customers. Foreign Currency Financial statements of foreign subsidiaries that use the local currency as their functional currency are translated into U.S. dollars at the end-of-period exchange rates or at historical exchange rates for purposes of consolidation. Revenues and expenses are translated using average exchange rates during the period. Translation adjustments are included in accumulated other comprehensive loss within stockholders’ deficit. Gains and losses resulting from transactions denominated in a currency other than the functional currency are included in other income, net in the condensed consolidated statements of operations. The Company recognized $1.1 million and $0.7 million foreign currency exchange gains for the three months ended March 31, 2024 and 2023, respectively. Convertible Promissory Notes The Company has elected the fair value option to account for its outstanding convertible promissory notes. Under the fair value option, the convertible promissory notes must be recorded at their initial fair value on the date of issuance, any modification, and at the end of each reporting period end date thereafter. Changes in the estimated fair value of the convertible promissory notes are recognized as non-cash gains or losses in other income, net in the condensed consolidated statements of operations. Contracts in Equity The Company classifies contracts in equity, including warrants to purchase shares of the Company’s common stock, that do not meet the indexation guidance as liabilities. At the end of each reporting period, such liability classified instruments are remeasured and changes in fair value during the reporting period are recognized within the condensed consolidated statements of operations until the earlier of the exercise, settlement, or expiration. The Company classifies contracts in equity, including the Legacy GCT Earnouts and Sponsor Earnouts (discussed in Note 3), that meet the indexation and equity classification guidance as a component of stockholders’ deficit and are not subject to fair value remeasurements. Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS” Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these condensed consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recent Accounting Pronouncements Adopted In August 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) Contracts in Entity’s Own Equity (Subtopic 815-40) In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805) Company adopted this guidance effective January 1, 2024, and noted no material impact on the Company’s condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820) In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740)

Reverse Recapitalization

Reverse Recapitalization	3 Months Ended
	Mar. 31, 2024
Reverse Recapitalization
Reverse Recapitalization	3. Reverse Recapitalization In connection with the Business Combination described in Note 1, Concord III completed the acquisition of Legacy GCT and acquired 100% of Legacy GCT’s common stock. Legacy GCT received net proceeds of $17.1 million from the PIPE Financing (as defined below). Concord III incurred total direct transaction costs of $13.1 million, which were expensed by Concord III, and of which $0.9 million related to the PIPE Financing. Legacy GCT incurred transaction costs of $8.9 million, consisting of legal, accounting, and other professional fees, which were recorded as additional paid-in capital. Each share of Legacy GCT capital stock received a deemed value of $10.00 per share after giving effect to the applicable exchange ratio of 0.1868. Upon Closing of the Business Combination, the following occurred: ● Each share of Legacy GCT common stock issued and outstanding prior to the Closing was cancelled and converted into the right to receive a number of shares of the Company common stock at the exchange ratio of 0.1868 . ● Each outstanding instrument of Legacy GCT stock options, restricted stock units (“RSUs”) and warrant shares were converted into equivalent Company stock options, RSUs and warrant shares with the same terms and conditions and at the exchange ratio of 0.1868 . ● Certain GCT convertible promissory notes, including the CVT Financing (see Note 7), were automatically converted into the right to receive a number of shares of the Company common stock at the conversion price of $6.67 per share (see Note 7). The number of shares of common stock issued and outstanding immediately following consummation of the Business Combination was (in thousands): ​ ​ ​ ​ Shares Common stock of Concord III outstanding prior to the Business Combination 3,941 Less: redemption of Concord III’s common stock (3,766) Sponsor earnout common stock outstanding prior to the Business Combination 8,625 Common stock of Concord III issued and outstanding 8,800 Common stock issued in PIPE Financing 4,530 Legacy GCT common stock 32,503 Total common stock issued and outstanding 45,833 ​ The Business Combination was accounted for as a reverse recapitalization under U.S. GAAP because Legacy GCT was determined to be the accounting acquirer under the FASB’s Accounting Standards Codification (“ASC”) Topic 805, Business Combinations Legacy GCT was determined to be the accounting acquirer based on evaluation of the following facts and circumstances: ● Legacy GCT stockholders comprise a relative majority of the voting power of GCT; ● Legacy GCT stockholders have the ability to nominate a majority of the members of the board of directors of GCT; ● Legacy GCT’s operations prior to the Business Combination will comprise the only ongoing operations of GCT; ● Legacy GCT’s senior management comprises the senior management of GCT; ● GCT substantially assuming the Legacy GCT name; ● Legacy GCT’s headquarters will become GCT’s headquarters; and ● Concord III did not meet the definition of a business. PIPE Financing Concurrent with the execution of the Business Combination Agreement, certain investors (the “PIPE Investors”) entered into subscription agreements (the “PIPE Subscription Agreements”) pursuant to which the PIPE Investors had committed to purchase in a private placement an aggregate of 4,529,967 shares of Company’s Common Stock (the “PIPE Shares”) at a purchase price of $6.67 per share for an aggregate purchase price of $30.2 million (the “PIPE Financing”). The purchase of the PIPE Shares was conditioned upon the consummation of the Business Combination. The PIPE Financing was consummated immediately prior to the Closing. The Company received net proceeds of $17.1 million from the PIPE Financing. Private Placement Warrants and Public Warrants In November 2021, Concord III issued warrants to purchase shares of Concord III’s common stock that were assumed by the Company at the Closing of the Business Combination on the same terms and conditions: (i) 9,400,000 warrant shares that were issued in a private placement and held by the sponsor and another company (the “private placement warrants”) and (ii) 17,250,000 warrant shares that were issued in connection with the initial public offering of Concord III (the “public warrants”). Collectively these warrant shares are referred to as “private and public warrants” and included settlement provisions that precluded equity classification. The private placement warrants were reallocated at the Closing of the Business Combination as follows: (i) 4,492,650 warrants were vested and retained by the sponsor parties, (ii) 2,087,350 warrants were reallocated from the sponsor parties to certain recipients at Legacy GCT’s discretion to incentivize investment, and (iii) 2,820,000 were forfeited by the sponsor parties. The Company has historically accounted for the private and public warrants as liability-classified financial instruments. This conclusion is based on the applicable provisions of the private and public warrants, including their settlement terms upon a change in control or similar transactions that precluded equity classification. After the Closing, the private and public warrants remained liability-classified as the applicable provisions did not change and apply to future operations of the Company. Legacy GCT Earnout Shares At the Closing of the Business Combination, former Legacy GCT stockholders and other investors of Legacy GCT have the right to receive up to an aggregate of 20,000,000 shares of Company common stock (“Earnout Shares”), if at any time during the period starting 60 trading days following the Closing and expiring on the 5 th In the event of a future transaction that results in a change in control in which shares of Company common stock are converted into the right to receive cash or other consideration having a value equal to or in excess of a triggering event, then the Legacy GCT Earnout Shares subject to the applicable triggering event that have not been previously issued will be issued to the Legacy GCT stockholders effective as of immediately prior to the consummation of such transaction. In the event of a transaction that results in a change in control in which shares of Company common stock are converted into the right to receive cash or other consideration having a value less than a triggering event, then the Earnout Shares subject to the applicable triggering event that have not been previously issued will be forfeited. The Legacy GCT Earnout shares have been recognized at fair value of approximately $108.8 million upon the Closing and classified within stockholders’ deficit as the Legacy GCT Earnout shares are indexed to the common stock and are otherwise not precluded from equity classification based on their settlement provisions. The fair value of the Legacy GCT Earnout Shares was determined based on a valuation using a Monte Carlo simulation with key inputs and assumptions such as stock price, term, dividend yield, risk-free rate, and volatility. Due to the fact that the Company does not have any retained earnings, the Company recorded Sponsor Earnout Shares Concurrently with entering into the Business Combination Agreement, the sponsor parties and the Company entered into that certain sponsor support agreement, as amended, modified or supplemented (the “Sponsor Support Agreement”). Pursuant to the terms of the Sponsor Support Agreement, the sponsor parties have the right to receive an aggregate of 1,920,375 shares of the Company common stock multiplied by the Sponsor Earnout Ratio (as defined in the Sponsor Support Agreement) (“Sponsor Earnout Shares”), if at any time during the period starting 6 months following the Closing and expiring on the 5 th one one one The Sponsor Earnout Shares have been recognized at fair value of approximately $10.4 million upon the Closing and classified within stockholders’ deficit as the Sponsor Earnout Shares are indexed to the common stock and are otherwise not precluded from equity classification based on their settlement provisions. The fair value of the Sponsor Earnout Shares was determined based on a valuation using a Monte Carlo simulation with key inputs and assumptions such as stock price, term, dividend yield, risk-free rate, and volatility. Since the Business Combination is accounted for as a reverse recapitalization, the issuance of the Sponsor Earnout Shares are treated as a deemed dividend. Since the Company does not have retained earnings, the issuance of the Sponsor Earnout Shares at the Closing is recorded within additional paid-in capital and has a net nil impact on stockholders’ deficit during the period ended March 31, 2024. In future reporting periods, the Company will monitor that the Sponsor Earnout shares meet the equity classification criteria until expiration or settlement.

Disaggregation of Revenue

Disaggregation of Revenue	3 Months Ended
	Mar. 31, 2024
Disaggregation of Revenue
Disaggregation of Revenue	4. Disaggregation of Revenue Disaggregation of revenues from contracts with customers is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2024 ​ Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ ​ At a point in time ​ $ 2,378 ​ $ — ​ $ 2,378 Over time ​ — ​ 887 ​ 887 Total ​ $ 2,378 ​ $ 887 ​ $ 3,265 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2023 ​ Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 599 ​ $ — ​ $ 599 Over time ​ — ​ 2,463 ​ 2,463 Total ​ $ 599 ​ $ 2,463 ​ $ 3,062 ​ Net revenues categorized by customer location are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ 2024 ​ 2023 Korea ​ $ 2,000 ​ $ — Germany ​ 796 ​ — United States ​ 389 ​ 1,968 China ​ 80 ​ 1,094 Total ​ $ 3,265 ​ $ 3,062 ​ Contract Assets and Liabilities Details of contract assets and liabilities is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 Contract assets ​ $ 4,313 ​ $ 3,439 Assets recognized for costs incurred to fulfill a contract (*) ​ 13 ​ 12 Contract liabilities ​ 35 ​ 48 (*) The balances are included in prepaid expenses and other current assets in the accompanying condensed consolidated balance sheets. Net revenues recognized in relation to contract liabilities are as follows as of the periods indicated (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 March 31, 2023 Net revenues recognized that were included in the contract liabilities balance at the beginning of the period ​ $ 12 ​ $ 650 ​

Fair Value of Measurements

Fair Value of Measurements	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value of Measurements
Fair Value of Measurements	5. Fair Value of Measurements Fair value hierarchy classifications of the financial instruments that are measured at fair value on a recurring basis are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 10,317 ​ $ 10,317 Warrant liabilities ​ — ​ — ​ 10,584 ​ 10,584 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033 ​ Valuation techniques and the inputs The table below presents valuation techniques and inputs used in the fair value measurement categorized within Level 3 of the fair value hierarchy (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation techniques Inputs March 31, 2024 December 31, 2023 Convertible promissory notes, current Discounted Cash Flow Model (“DCF”) Discount rate, risk-free rate, credit spread, contractual cash flows ​ $ 5,645 ​ $ — ​ ​ PWERM (“Probability-Weighted Expected Return Method”) ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 27,794 Convertible promissory notes, net of current Binomial Lattice Model (“BLM”) Stock price, volatility, remaining term, risk-free rate, credit spread ​ $ 4,672 ​ $ — ​ ​ PWERM ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 6,239 Warrant liabilities – private and public warrants Black Scholes Merton Model (“BSM”) or BLM Exercise price, term to expiration, volatility, risk-free rate ​ $ 9,150 ​ $ — Warrant liabilities - other ​ ​ ​ ​ $ 1,434 $ — ​ As of March 31, 2024, the key inputs for the convertible promissory notes, current using the DCF were as follows: remaining term of 0.25 years and a discount rate of 10.2%. As of March 31, 2024, the key inputs for the convertible promissory notes, net of current using the BLM were as follows: stock price of $6.58, volatility of 32.2%, remaining term of 1.9 years, risk-free rate of 4.6%, and credit spread of 5.0%. As of March 31, 2024, the key inputs for the private placement warrants using the BSM were as follows: exercise price of $11.50 per share, term to expiration of 5 years, volatility range of 19.4% and a risk-free rate of 4.2%. As of March 31, 2024, the key inputs for the public warrants using the BLM were as follows: exercise price of $11.50 per share and term to expiration of 5.0 years. As of March 31, 2024, the key inputs for the warrant liabilities – other using the BSM were as follows: an exercise price of $5.00 per share, or $10.00 per share or $18.75 per share, term to expiration ranging from 0.4 years to 2.6 years, volatility ranging from 29.5% to 32.7%, and a risk-free rate ranging from 4.4% to 5.4%. As of December 31, 2023, the PWERM was used as Legacy GCT was a private company. After the Closing, and as of March 31, 2024, the valuation techniques used reflect that the Business Combination was consummated. The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Convertible promissory notes fair value - beginning of period ​ $ 34,033 ​ $ 31,166 Change in fair value of convertible promissory notes ​ 1,203 ​ (549) Conversion of convertible promissory notes ​ (41,209) ​ — Borrowing of convertible promissory notes ​ 16,290 ​ — Convertible promissory notes fair value - end of period ​ $ 10,317 ​ $ 30,617 ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Warrant Liabilities Fair value - beginning of period ​ $ — ​ $ — Private and public warrants assumed at Closing ​ 5,958 ​ — Change in fair value of warrant liabilities ​ 4,626 ​ — Warrant Liabilities Fair value - end of period ​ $ 10,584 ​ $ — ​ The gains and losses from fair value re-measurement of Level 3 financial liabilities are recorded as other income, net in the condensed consolidated statements of operations.	2. Fair Value of Measurements Fair Value Hierarchy Recurring fair value measurements Fair value hierarchy classifications of the financial instruments that are measured at fair value on a recurring basis as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2023 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033 ​ Recurring fair value measurements, continued ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2022 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 31,166 ​ $ 31,166 ​ Valuation techniques and the inputs The table below presents valuation techniques and inputs used in the fair value measurement categorized within Level 3 of the fair value hierarchy as of December 31, 2023 and 2022. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Valuation techniques Inputs 2023 2022 Convertible promissory notes, current PWERM Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ 27,794 ​ $ 31,166 Convertible promissory notes, net of current ​ ​ ​ 6,239 ​ — ​ The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities for the years ended December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Fair value as of beginning of period ​ $ 31,166 ​ $ 56,996 Change in fair value of convertible promissory notes ​ 1,428 ​ 450 Conversion of convertible promissory notes ​ (61) ​ (33,140) Repayment of convertible promissory notes ​ (500) ​ (1,140) Transfer of convertible promissory notes to bank borrowings ​ — ​ (1,000) Borrowing of convertible promissory notes ​ 2,000 ​ 9,000 Fair value as of end of period ​ $ 34,033 ​ $ 31,166 ​ The gains and losses from fair value re-measurement of Level 3 financial liabilities are recorded as other income (expense), net in the consolidated statements of operations.

Balance Sheet Components

Balance Sheet Components	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Balance Sheet Components
Balance Sheet Components	6. Balance Sheet Components Inventory Inventories consists of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Raw materials ​ $ 414 ​ $ 448 Work-in-process ​ 498 ​ 601 Finished goods ​ 872 ​ 437 Total inventory ​ $ 1,784 ​ $ 1,486 ​ There were no write-downs of inventory into cost of net revenues for the three months ended March 31, 2024 and 2023. Prepaid expenses and other assets Prepaid expenses and other assets consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Prepaid expenses ​ $ 3,345 ​ $ 433 Prepaid inventory ​ ​ 1,429 ​ ​ 279 Lease deposit ​ 413 ​ 434 Other receivables and current assets ​ 279 ​ 117 IPO expenses ​ — ​ 1,643 Prepaid expenses and other current assets ​ $ 5,466 ​ $ 2,906 ​ Accrued and other current liabilities Accrued and other current liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Payroll and related expenses ​ $ 9,830 ​ $ 9,880 Accrued payables ​ ​ 7,853 ​ ​ 6,319 Other taxes payable ​ ​ 3,399 ​ ​ 158 Current portion of interest payable ​ ​ 3,395 ​ ​ 6,915 Professional fees ​ 444 ​ 499 Royalty and license fee ​ 60 ​ 58 Product warranty ​ 64 ​ 55 Other ​ 107 ​ 72 Accrued and other current liabilities ​ $ 25,152 ​ $ 23,956 ​	3. Balance Sheet Components Inventory Inventory as of December 31, 2023 and 2022 consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Raw materials ​ $ 448 ​ $ 182 Work-in-process ​ 601 ​ 891 Finished goods ​ 437 ​ 2,407 ​ ​ $ 1,486 ​ $ 3,480 ​ Prepaid expenses and other assets Prepaid expenses and other assets as of December 31, 2023 and 2022 consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 IPO expenses ​ $ 1,643 ​ $ — Intellectual property rights ​ 761 ​ 861 Lease deposit ​ 554 ​ 555 Prepaid expenses ​ 433 ​ 799 Prepaid inventory ​ 279 ​ 1,310 Other receivables ​ 105 ​ 102 Costs incurred to fulfill a contract ​ 12 ​ 39 ​ ​ 3,787 ​ 3,666 Less: Non-current assets ​ (881) ​ (993) Prepaid expenses and other current assets ​ $ 2,906 ​ $ 2,673 ​ Property and equipment, net Property and equipment, net as of December 31, 2023 and 2022 consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Production equipment ​ $ 14,887 ​ $ 14,800 IT equipment ​ 1,127 ​ 1,212 Furniture and fixtures ​ 784 ​ 799 Leasehold improvements ​ 293 ​ 388 Fixed assets in process ​ — ​ 39 Total property and equipment ​ 17,091 ​ 17,238 Less: accumulated depreciation and amortization ​ (16,319) ​ (16,127) ​ ​ $ 772 ​ $ 1,111 ​ Depreciation expense was approximately $640,000 and $518,000 for the years ended December 31, 2023 and 2022, respectively. ​ 3. Balance Sheet Components Leases The Company is obligated under finance leases covering certain IT equipment that expire at various dates during the next year. The Company also has several noncancellable operating leases, primarily for office equipment and office space that expire over the next four years. The office space leases generally contain renewal options for periods ranging from two Payments due under the lease contracts include fixed payments plus, for many of the Company’s leases, variable payments. For office space leases, variable payments include payments for the Company’s proportionate share of the building’s property taxes, insurance, and common area maintenance. For office equipment leases for which the Company has elected not to separate lease and non-lease components, maintenance services are provided by the lessor at a fixed cost and are included in the fixed lease payments for the single, combined lease component. The Company also elected to discount its office equipment lease liabilities using a risk-free rate. The components of lease expense for the years ended December 31, 2023 and 2022 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Operating lease expense ​ $ 772 ​ $ 733 Finance lease expense ​ ​ Amortization of right of use assets ​ 14 ​ 18 Interest on lease liabilities ​ 1 ​ 2 Total finance lease expense ​ 15 ​ 20 ​ ​ $ 787 ​ $ 753 ​ Other information related to leases for the years ended December 31, 2023 and 2022 was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Supplemental cash flow information: ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ Cash used in operations for operating leases ​ $ 766 ​ $ 770 ​ Cash used in operations for finance leases ​ 1 ​ 2 ​ Payments made on finance leases ​ 17 ​ 24 ​ ROU assets obtained in exchange for lease obligations: ​ ​ ​ Operating leases ​ 1,476 ​ 826 ​ Weighted average remaining lease term: ​ ​ ​ Operating leases ​ 2.25 years ​ 3.57 years ​ Finance leases ​ — ​ 0.90 years ​ Weighted average discount rate: ​ ​ ​ Operating leases ​ 4.66 % 4.00 % Finance leases ​ — ​ 9.70 % ​ ​ 3. Balance Sheet Components Leases Amounts disclosed for ROU assets obtained in exchange for lease obligations include amounts added to the carrying amount of ROU assets resulting from lease modifications and reassessments. Maturities of lease liabilities under noncancellable leases as of December 31, 2023 are as follows: ​ ​ ​ ​ ​ ​ Operating (in thousands) ​ leases 2024 ​ $ 743 2025 ​ 712 2026 ​ 169 Total undiscounted lease payments ​ 1,624 Less: imputed interest ​ (94) Total lease liabilities ​ $ 1,530 ​ Intangibles, net Intangibles, net as of December 31, 2023 and 2022 consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Intellectual properties ​ $ 1,118 ​ $ 943 Intangible assets in process ​ — ​ 180 Total acquired intangibles ​ 1,118 ​ 1,123 Less: accumulated amortization ​ (873) ​ (451) ​ ​ $ 245 ​ $ 672 ​ Amortization expense was approximately $422,000 and $147,000 for the years ended December 31, 2023 and 2022, respectively. Accrued and other current liabilities Accrued and other current liabilities as of December 31, 2023 and 2022 consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Payroll and related expenses ​ $ 10,038 ​ $ 6,635 Accrued payables ​ 6,319 ​ 2,233 Royalty and license fee ​ 58 ​ 37 Professional fees ​ 499 ​ 479 Current portion of interest payable ​ 6,915 ​ 2,944 Product warranty ​ 55 ​ 64 Other ​ 72 ​ 104 ​ ​ $ 23,956 ​ $ 12,496 ​ ​ 3. Balance Sheet Components Other liabilities Other liabilities as of December 31, 2023 and 2022 consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Severance payments liability ​ $ 92 $ 76 Interest payable ​ 16 — ​ ​ $ 108 $ 76 ​

Debt

Debt	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Debt
Debt	7. Debt The Company’s outstanding debt was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 ​ ​ Principal ​ Fair Value ​ Principal ​ Fair Value Convertible promissory notes: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Historical convertible promissory notes ​ $ 5,630 ​ $ 5,645 ​ $ 35,347 ​ $ 34,033 2023 & 2024 convertible promissory notes ​ 5,000 ​ 4,672 ​ — ​ — Borrowings: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ KEB Hana Bank ​ 6,682 ​ 6,682 ​ 6,980 ​ 6,980 IBK Industrial Bank ​ 6,831 ​ 6,831 ​ 7,135 ​ 7,135 Note payable (one individual investor) ​ 1,000 ​ 1,000 ​ 1,000 ​ 1,000 M-Venture Investment, Inc. ​ 7,425 ​ 7,425 ​ 7,756 ​ 7,756 Anapass, Inc, related party ​ 9,653 ​ 9,653 ​ 10,082 ​ 10,082 i Best Investment Co., Ltd ​ 7,425 ​ 7,425 ​ 10,082 ​ 10,082 Kyeongho Lee, related party ​ 824 ​ 824 ​ 1,474 ​ 1,474 Total debt ​ $ 50,470 ​ 50,157 ​ $ 79,856 ​ 78,542 Less: current portion ​ ​ ​ ​ (45,485) ​ ​ ​ ​ (72,303) Debt, net of current portion ​ ​ ​ ​ $ 4,672 ​ ​ ​ ​ $ 6,239 ​ The Company elected the fair value option for the 2023 & 2024 convertible promissory notes and the historical convertible promissory notes (see Note 5). The Company’s other borrowings approximate their fair value because interest rates are at prevailing market rates and/or the short-term nature of the remaining obligations. See Note 14 for additional information on related parties. Expected future minimum principal payments under the Company’s total debt is as follows as of March 31, 2024 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible ​ ​ ​ ​ ​ ​ Notes ​ ​ ​ ​ ​ ​ Years ​ Payable ​ Borrowing ​ Total 2024, remainder ​ $ 5,630 ​ $ 39,840 ​ $ 45,470 2025 ​ — ​ — ​ — 2026 ​ 5,000 ​ — ​ 5,000 Total debt ​ $ 10,630 ​ $ 39,840 ​ $ 50,470 ​ Convertible Promissory Notes Historical Convertible Promissory Notes Between 2017 and 2022, the Company issued convertible promissory notes to various investors with maturity dates ranging from October 2020 to April 2025. The annual interest rates varied between 4.0% and 7.0%. In November 2023, the Company entered into an amendment with certain convertible promissory noteholders to modify the conversion terms such that these notes were automatically convertible upon a special purpose acquisition company (“SPAC”) transaction. In March 2024, upon the Closing of the Business Combination, an aggregate principal and interest amount of $32.1 million converted into 4,258,223 shares of common stock at a conversion price of $10.00. As of March 31, 2024, the remaining principal and interest amount of $7.9 million was outstanding and related to two noteholders where conversion is at each noteholder’s discretion and at a conversion price of $3.50 per share. In April 2024, the Company repaid one of the convertible promissory notes (see Note 17). 2023 & 2024 Convertible Promissory Notes In November 2023, February 2024 and March 2024, the Company issued convertible promissory notes to certain investors (the “CVT Investors”), pursuant to which the CVT Investors agreed to lend to the Company an aggregate principal amount of $13.3 million. These notes had maturity dates ranging from November 2026 to March 2027, bore an interest rate of 5.0% and were automatically convertible upon IPO or SPAC transaction. In March 2024, upon the Closing of the Business Combination, an aggregate principal and interest amount of $13.4 million converted into 2,004,535 shares of common stock at a conversion price of $6.67. As of March 31, 2024, none of the notes issued to CVT Investors remain outstanding. In February 2024, the Company issued a convertible promissory note to a strategic investor for a principal amount of $5.0 million, which matures in February 2026 and bears an interest rate of 5.0% per annum. On or after the earlier of (i) six months from the issuance date of the convertible promissory note and (ii) the Closing of the Business Combination, the noteholder may demand that the Company convert all principal and interest due under the convertible promissory note into shares of Company’s common stock, at a conversion price of $10.00 per share. This note includes customary representations, warranties, and events of default, as well as a covenant relating to the performance of obligations by the Company related to the Company’s 5G activity. As of March 31, 2024, the remaining principal and interest amount of $5.0 million was outstanding. Borrowings Pursuant to Term Loan and Security Agreements KEB Hana Bank In July 2016, the Company entered into an unsecured term loan agreement with KEB Hana Bank pursuant to which it borrowed KRW 9.0 billion ($6.7 million), bearing a variable interest rate (2.6% initial annual interest rate and 5.2% as of March 31, 2024), paid monthly, and maturing in July 2017. The terms of such unsecured term loan agreement have been extended annually for additional one-year terms since 2017, and the maturity date is July 2024. Anapass, Inc., a related party, provided certificates of deposit as collateral to KEB Hana Bank to secure the Company’s obligations under this loan (see Note 8). As of March 31, 2024, the remaining principal and interest amount of $6.7 million was outstanding. IBK Industrial Bank In January 2017, the Company entered into a term loan agreement with IBK Industrial Bank pursuant to which the Company borrowed KRW 9.2 billion ($6.8 million). The term loan has a maturity date in November 2024 and bears an annual interest rate of 4.9%. As of March 31, 2024, the remaining principal and interest amount of $6.8 million was outstanding. Note Payable (One Individual Investor) In June 2021, the Company entered into a note payable agreement with an individual investor pursuant to which the Company borrowed $1.0 million. The note has a maturity date in June 2024 and bears an annual interest rate of 4.0%. In April 2022, the Company entered into an amendment with this one individual investor to remove the conversion right from the note payable. As of March 31, 2024, the remaining principal and interest amount of $1.1 million was outstanding. M-Venture Investment, Inc. In October 2021, the Company entered into a term loan and security agreement with M-Venture Investment, Inc. pursuant to which the Company borrowed KRW 5.0 billion ($3.7 million) and repaid KRW 0.6 billion ($0.4 million) and KRW 0.4 billion ($0.3 million) in 2021 and 2022, respectively, such that KRW 4.0 billion ($3.0 million) remained outstanding. The term loan has a maturity date in October 2024 and bears an annual interest rate of 6.5%. As of March 31, 2024, the remaining principal and interest amount of $3.1 million was outstanding. In April 2022, the Company entered into a term loan and security agreement with M-Venture Investment, Inc. pursuant to which the Company borrowed amounts in two draws of KRW 1.0 billion ($0.7 million) and KRW 5.0 billon ($3.7 million), respectively. The term loan has a maturity date in April 2024 and each respective draw bears an annual interest rate of 6.5% and 8.7%. As of March 31, 2024, the remaining principal and interest amount of $4.8 million was outstanding. In April 2024, the Company executed amendments with M-Venture Investment, Inc. (see Note 17). Anapass, Inc., Related Party In July 2016, the Company entered into a loan agreement with Anapass, Inc. pursuant to which the Company borrowed KRW 6.0 billion ($4.5 million) in a term loan. Interest only payments are due monthly at 5.5% per annum and the principal amount of the term loan is due on the maturity date of July 2024. The loan is collateralized by the Company’s assets as described under the Assets Pledged as Collateral (see Note 8). As of March 31, 2024, the remaining principal and interest amount of $4.5 million was outstanding. In May and September 2022, the Company entered into two term loan agreements with Anapass, Inc. pursuant to which the Company borrowed KRW 3.0 billion ($2.2 million) and KRW 4.0 billion ($3.0 million) in term loans. The term loans have respective maturity dates in May 2024 and September 2024 and both bear an annual interest rate of 5.5%. As of March 31, 2024, the remaining principal and interest amount of $5.2 million was outstanding. i Best Investment Co., Ltd From 2022 and 2023, the Company entered into multiple term loans and security agreements with i Best Investment Co., Ltd pursuant to which it borrowed principal amounts in six draws with an aggregate principal balance of KRW 14.0 billion ($10.3 million). All of the term loans have a maturity date in June 2024 and bear an annual interest rate of 6.5%. In December 2023, the Company made a $0.8 million repayment of the outstanding principal and interest on its second draw. In March 2024, the Company made a $2.3 million repayment of the outstanding principal and interest amount of its fourth draw. As of March 31, 2024, the remaining principal and interest amounts outstanding were as follows: $3.3 million outstanding on its first draw, $1.6 million outstanding on its third draw, $2.3 million outstanding on its fifth draw and $0.8 million on its sixth draw. Kyeongho Lee, Related Party From 2017 and 2021, the Company entered into multiple promissory note and term loan agreements with Kyeongho Lee pursuant to which the Company borrowed (a) KRW 500.0 million ($0.4 million), and KRW 500.0 million ($0.4 million) in promissory notes, and (b) KRW 1.0 billion ($0.7 million) and KRW 110.0 million ($0.1 million) in term loans. The promissory notes have a maturity date in November 2024 and bear an annual interest rate varying from 7.5% and 9.0%. During the three months ended March 31, 2024, the Company repaid in full one of the term loans. The term loan has a maturity date in May 2024 and bears an annual interest rate of 0.0%. As of March 31, 2024, the remaining principal and interest amount of $0.7 million and $82,000 was outstanding as it related to the promissory notes and a term loan, respectively.	4. Debt Borrowings ​ ​ ​ ​ ​ ​ ​ ​ ​ Category Creditor Maturity date Annual interest rate Korean Won KEB Hana Bank (*1) 7/12/2024 5.23 % Korean Won IBK Industrial Bank (*1) 11/20/2024 4.89 % Korean Won Anapass, Inc. 7/25/2024 5.50 % Korean Won Anapass, Inc. 5/10/2024 5.50 % Korean Won Anapass, Inc. 9/15/2024 5.50 % Korean Won Kyeongho Lee 11/19/2024 9.00 % Korean Won Kyeongho Lee 5/27/2024 0 % Korean Won Kyeongho Lee 11/24/2023 6.80 % Korean Won Kyeongho Lee 11/30/2024 7.50 % Korean Won Kyeongho Lee 12/2/2024 (*9) 7.50 % Korean Won M-Venture Investment, Inc. (*3) 10/29/2024 6.50 % Korean Won M-Venture Investment, Inc. (*4) 4/26/2024 6.50% - 8.65 %(*6) Korean Won i Best Investment Co., Ltd. (*5) 3/14/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. (*7) 12/22/2023 6.50 % Korean Won i Best Investment Co., Ltd. 3/12/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. 1/12/2024 (*9) 6.50 % Korean Won i Best Investment Co., Ltd. 3/14/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. 1/26/2024 (*2) 6.50 % Promissory Note One (1) individual investor 6/30/2024 4.00 % (*1) The limits for borrowings from KEB Hana Bank and IBK Industrial Bank are $6,980,000 and $7,135,000, respectively, and the bank deposit of Anapass, Inc., a related party, is pledged as collateral for borrowings from KEB Hana Bank and IBK Industrial Bank (see Notes 5 and 12). As of the current fiscal year end, collateral was provided to Anapass, Inc. in relation to the borrowings from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. (see Notes 5 and 12). (*2) Maturity date was extended for five ​ 4. Debt Borrowings (*3) (*4) (*5) (*6) (*7) (*8) three (*9) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ Category ​ Creditor ​ December 31, 2023 ​ December 31, 2022 Korean Won KEB Hana Bank (*1) ​ $ 6,980 ​ $ 7,102 Korean Won IBK Industrial Bank (*1) ​ 7,135 ​ 7,260 Korean Won Anapass, Inc. ​ 4,653 ​ 4,735 Korean Won Anapass, Inc. ​ 2,327 ​ 2,367 Korean Won Anapass, Inc. ​ 3,102 ​ 3,156 Korean Won Kyeongho Lee ​ 388 ​ 395 Korean Won Kyeongho Lee ​ 85 ​ 87 Korean Won Kyeongho Lee ​ — ​ 24 Korean Won Kyeongho Lee ​ 388 ​ 395 Korean Won Kyeongho Lee ​ 613 ​ 789 Korean Won M-Venture Investment, Inc. (*3) ​ 3,102 ​ 3,156 Korean Won M-Venture Investment, Inc.(*4) ​ 4,653 ​ 4,734 Korean Won i Best Investment Co., Ltd. (*5) ​ 3,102 ​ 3,156 Korean Won i Best Investment Co., Ltd. (*7) ​ — ​ — Korean Won i Best Investment Co., Ltd. ​ 1,551 ​ — Korean Won i Best Investment Co., Ltd. ​ 2,327 ​ — Korean Won i Best Investment Co., Ltd. ​ 2,327 ​ — Korean Won i Best Investment Co., Ltd. ​ 776 ​ — Promissory Note One (1) individual investor ​ 1,000 ​ 1,000 Bank Borrowings ​ $ 44,509 ​ $ 38,356 ​ Maturities of borrowings as of December 31, 2023 were as follows: ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2024 ​ $ 44,509 Total ​ $ 44,509 ​ ​ 4. Debt Convertible Notes Details of convertible notes are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Category ​ Creditor ​ December 31, 2023 ​ December 31, 2022 Current convertible notes (*1) ​ ​ 1st SG Ace Inc. (*2) ​ $ 7,620 ​ $ 8,461 2nd M-Venture Investment, Inc. and one (1) institution (*3) ​ 7,620 ​ 8,461 7th NA Korea Trans Fund No.4, one (1) institution and eight(8) individual investors (*4) ​ 2,198 ​ 1,932 16th NA Korea Trans Fund No.4 and two (2) individual investors ​ 387 ​ 330 22nd i Best Investment Co., Ltd. ​ 3,233 ​ 2,746 23rd Jeju Semiconductor Corp. ​ 908 ​ 771 24th One (1) individual investor ​ 665 ​ 565 25th M-Venture Investment Inc. (*5) ​ — ​ 3,511 26th Access Bio, Inc. ​ 5,163 ​ 4,389 ​ Subtotal ​ 27,794 ​ 31,166 Non-current convertible notes ​ ​ 25th M-Venture Investment Inc. (*5) ​ 3,614 ​ — 27th Blacktree Co., Ltd. ​ 2,625 ​ — ​ Subtotal ​ 6,239 ​ — ​ Total ​ $ 34,033 ​ $ 31,166 (*1) (*2) (*3) (*4) (*5) During the year ended December 31, 2022, GNI Partners Co., Ltd. exercised their conversion right of the convertible note of $708,000, thereby 202,168 common shares were issued. ​ 4. Debt Convertible Notes, During the year ended December 31, 2022, the right to early redemption was exercised for 8th convertible notes of $740,000, 9th convertible notes of $100,000 and 12th convertible notes of $340,000 issued to seven (7) individual investors and redemption was made in full during 2022. During the year ended December 31, 2022, the amendment to the 21st convertible note of $1 million issued to one (1) individual investor was made and conversion right was eliminated. The note with the right to claim early redemption was reclassed to short-term borrowings. During the year ended December 31, 2022, convertible notes of $32.5 million and unpaid interest of $2.6 million were converted into common shares due to the submission of listing eligibility review application to Korea Exchange, and common shares of 10,026,354 were issued. Maturities of convertible notes as of December 31, 2023, were as follows: ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2024 ​ $ 27,794 December 31, 2025 ​ 3,614 December 31, 2026 ​ 2,625 Total ​ $ 34,033 ​ Key terms for issuance of convertible notes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1st 2nd 7th 16th 22nd 23rd 24th 25th 26th 27th Issue Year ​ 2017 2017 2019 2020 2021 2021 2021 2022 2022 ​ 2023 Early repayment ​ (*1) (*1) (*2) (*1) (*1) (*1) (*1) (*2) (*3) ​ (*1) Repayment at maturity ​ The payment shall be made three years after the date of issue at an annual interest rate of 4% . The payment shall be made three years after the date of issue at an annual interest rate of 7% . The payment shall be made three years after the date of issue at an annual interest rate of 5% . The payment shall be made three years after the date of issue at an annual interest rate of 4% . ​ The payment shall be made three years after the date of issue at an annual interest rate of 5% . Rates applied at the repayment date ​ Upon repayment, there is a clause to reimburse the U.S. Dollar amount converted at the Won-Dollar exchange rate on the redemption date based on the Won amount converted at the Won-Dollar exchange rate at the date of issue. ​ N/A N/A N/A N/A N/A N/A ​ N/A Conversion price ​ $ 3.50 per share (*4) ​ ​ $ 6.67 per share ​ ​ 4. Debt, Convertible Notes, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1st 2nd 7th 16th 22nd 23rd 24th 25th 26th 27th Conversion - The holder of convertible notes can covert it at any time. ​ - If the Company issues a new equity instrument after issuing convertible notes, the holder of convertible notes may participate in conversion with the issuance price of the new equity instruments (1st, 2nd and 27th convertible notes) or $3.50 per share up to seven days prior to the issuance of the equity instruments. ​ - Conversion upon demand at holder’s discretion with conversion price equal to $3.50 ($6.67 for 27th convertible note) per share after issue date. ​ - Automatic conversion in an initial public offering (“IPO”) or business combination with SPAC (except for 1st and 24th convertible notes) (conversion price is adjusted to IPO price or SPAC conversion price). ​ - If the price at the time of issuance of a new equity instrument or the IPO is lower than $3.50, the conversion price of the convertible note is adjusted (except for 27th convertible note). ​ - Conversion price is adjusted every three months for one year after an IPO at KOSDAQ (However, adjusted price cannot be lower than 70% of $3.50 per share and cannot be higher than $3.50 per share) (7th convertible note). Number of convertible shares (*5) 5,142,858 shares ​ 553,790 shares 102,597 shares 874,286 shares 245,714 shares 180,000 shares 1,000,000 shares 1,428,571 shares 299,850 shares Collateral and guarantee (*6) ​ (*7) N/A (*8) N/A (*7) N/A (*7) N/A (*1) early repayment exercised once every quarter times in total for periods after from date issue convertible notes until from the date issue convertible notes (*2) times periods convertible convertible (*3) (*4) (*5) (*6) shares (*7) (*8) The convertible notes of the Company are designated as financial liabilities measured at fair value through profit or loss in accordance with ASC 840. Changes in fair value that occurred during the current period amounting to a gain of $2,619,000 (prior period: $2,673,000) and a loss of $4,047,000 (prior period: $3,123,000) were recognized as other income (expense), net on the consolidated statement of operations, respectively. In the year 2021, Amber International Ltd. acquired the 5th convertible note of $708,000, which was redeemed on behalf of the Company, in same conditions, and later the note was transferred to GNI Partners Co., Ltd. During the year 2022, GNI Partners Co., Ltd. exercised conversion rights and the note was converted to common shares in full. The 3rd convertible note issued to Shinsojae Energy Holdings Limited was transferred to NJ Holdings Inc. in June 2021. NJ Holdings Inc. exercised its conversion right during 2022, and as a result the 3rd convertible note was converted to common shares in full.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies.
Commitments and Contingencies	8. Commitments and Contingencies Litigation The Company is subject to various claims arising in the ordinary course of business. Although no assurance can be given, the Company believes that it is not a party to any litigation of which the outcome, if determined adversely, would individually, or in the aggregate, be reasonably expected to have a material adverse effect on the business, consolidated operating results, cash flows or financial position of the Company as of March 31, 2024. Third parties have from time to time claimed, and others may claim in the future, that the Company has infringed their past, current or future intellectual property rights. These claims, whether meritorious or not, could be time consuming, result in costly litigation, require expensive changes in the Company’s methods of doing business or could require the Company to enter into costly royalty or licensing agreements, if available. As a result, these claims could harm the Company’s business, consolidated operating results, cash flows, and financial position. Purchase Commitment The Company has certain commitments for outstanding purchase orders related to the manufacture of certain wafers utilized by the Company and other services that, once the wafers are placed into production, are noncancelable. Otherwise, these production agreements are cancellable at any time with the Company required to pay all costs incurred through the cancellation date. However, the Company has rarely cancelled these agreements once production has started. As of March 31, 2024, the Company had no outstanding noncancelable purchase commitments for these production agreements. In July 2020, the Company entered into a research and development agreement with Samsung Electronics Co., Ltd (“Samsung”). According to the agreement, the Company would design 5G chip products and Samsung would provide development and intellectual property support, mass production set up support including mask sets for manufacturing and engineering sample chip supply to the Company for a specific product. The total fee amount for the research and development (“R&D”) services pursuant to the agreement was $21.1 million. The Company bore the risk of R&D failure and was obligated to pay the $21.1 million total fee based on milestones defined in the agreement, of which $11.7 million was due based on development milestones and $9.4 million of additional NRE (“non-recurring engineering”) was to be paid within a maximum of 4 years In February 2024, the Company and Alpha Holdings Co., Ltd. (“Alpha”) entered into a foundry product development agreement related to 5G chip development for a total fee of $7.6 million. The Company bears the risk of R&D failure and is obligated to pay the fee based on milestones defined in the agreement. The Company recognizes R&D expenses based on an estimate of the percentage completion of services provided by Alpha during the respective financial reporting period. For the three months ended March 31, 2024, the Company recorded $3.5 million in R&D expenses related to services provided by Alpha. The aggregate unpaid amount related to this agreement is $5.0 million as of March 31, 2024. Assets Pledged as Collateral The Company has provided collateral to Anapass, Inc., a related party (see Note 14), for borrowings from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. in the amount of $6.7 million, $6.8 million and $9.7 million, respectively, as of March 31, 2024, and $7.0 million, $7.1 million and $10.1 million, respectively, as of December 31, 2023 (see Note 7). The following table includes a summary of the collateral provided to Anapass, Inc. (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, Secured ​ ​ 2024 ​ 2023 ​ Creditor Cash and cash equivalents ​ $ 16,122 ​ $ 254 ​ ​ Accounts receivable ​ ​ 5,118 ​ ​ 4,920 ​ Inventory ​ 1,784 ​ 1,486 Anapass, Inc. Property and equipment ​ 1,988 ​ 352 Intangible assets and others ​ 187 ​ 199 ​	5. Commitments and Contingencies ​ Litigation The Company is subject to various claims arising in the ordinary course of business. Although no assurance can be given, the Company believes that it is not presently a party to any litigation of which the outcome, if determined adversely, would individually, or in the aggregate, be reasonably expected to have a material adverse effect on the business, consolidated operating results, cash flows or financial position of the Company. Third parties have from time to time claimed, and others may claim in the future, that the Company has infringed their past, current or future intellectual property rights. These claims, whether meritorious or not, could be time consuming, result in costly litigation, require expensive changes in the Company’s methods of doing business or could require the Company to enter into costly royalty or licensing agreements, if available. As a result, these claims could harm the Company’s business, consolidated operating results, cash flows and financial position. Purchase Commitment The Company has certain commitments for outstanding purchase orders related to the manufacture of certain wafers utilized by the Company and other services that, once the wafers are placed into production, are noncancelable. Otherwise, these production agreements are cancellable at any time with the Company required to pay all costs incurred through the cancellation date. However, the Company has rarely cancelled these agreements once production has started. As of December 31, 2023 and 2022, the Company had outstanding noncancelable purchase commitments for these production agreements of $0 and $0.5 million, respectively. The Company entered into a research and development agreement with Samsung Electronics Co., Ltd (“Samsung”) in July 2020. According to the agreement, the Company designs 5G chip products and Samsung provides development and intellectual property support, mass production set up support including mask sets for manufacturing and engineering sample chip supply to the Company. Total fee amount of the agreement is $21.1 million composed of $11.7 million to be paid over development milestones and $9.4 million of additional NRE (non-recurring engineering) to be paid within maximum 4 years after planned product first shipment date. The Company bears the risk of R&D failure and is obligated to pay the fees based on milestones defined in the agreement. Pursuant to ASC 730-20, Research and Development, the Company expensed $0.4 million and $7.1 million related to this agreement for the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023 and 2022, $15.8 million and $15.4 million, respectively, of unpaid recorded expenses were included in accounts payable on the consolidated balance sheets. The aggregated unpaid amount on this agreement is $17.1 million as of December 31, 2023. Assets Pledged as Collateral The Company has provided collateral to Anapass, Inc., a related party, for borrowings of GCT R&D, a subsidiary of GCT, from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. in the amount of $7.0 million, $7.1 million and $10.1 million, respectively, as of December 31, 2023, and $7.1 million, $7.3 million and $10.3 million, respectively, as of December 31, 2022 (see Note 4). 5. Commitments and Contingencies, Assets Pledged as Collateral, Details of collateral provided to Anapass, Inc. are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) December 31, December 31, Secured ​ ​ 2023 ​ 2022 ​ Creditor Cash and cash equivalents ​ $ 254 ​ $ 1,363 Accounts receivable ​ 4,920 ​ 4,453 Inventory ​ 1,486 ​ 3,480 Anapass, Inc. Property and equipment ​ 352 ​ 485 Intangible assets and others ​ 199 ​ 531 ​

Common Stock

Common Stock	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Common Stock
Common Stock	9. Common Stock In connection with the Closing of the Business Combination, the Company increased its total number of authorized shares to 440,000,000 shares, consisting of 400,000,000 shares of common stock and 40,000,000 shares of preferred stock. The Company has reserved shares of common stock for issuance as follows (in thousands): ​ ​ ​ ​ ​ ​ March 31 December 31 ​ ​ 2024 ​ 2023 Warrants ​ 26,724 ​ 2,894 Shares available for future grant from 2024 plan ​ 3,983 ​ — Convertible promissory notes 800 1,835 Options issued and outstanding 668 668 Shares available for future grant from 2024 ESPP 600 — RSUs outstanding 392 392 Shares available for future grant from 2011 plan — 113 Total 33,167 5,902 ​	6. Common Stock The Company’s total number of authorized shares is 200,000,000 shares and the total number of common shares issued is 129,395,774 $0.001 The Company has reserved the following shares of authorized but unissued common stock as of December 31, 2023 ​ ​ ​ Options outstanding 3,579,294 RSUs outstanding 2,099,970 Shares available for grant from 2011 plan 605,826 Warrants 9,200,000 Convertible promissory notes 9,827,666 Total 25,312,756 ​

Warrants

Warrants	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Warrants
Warrants	10. Warrants The following table represents a summary of warrants to purchase shares of the Company’s common stock that are outstanding (in thousands, except for exercise price): ​ ​ ​ ​ ​ ​ ​ Issue Date March 31, 2024 Exercise Price Expiration August 2021 ​ 299 ​ $ 10.00 - $18.75 ​ (1) September 2021 300 ​ $ 5.00 (1) February 2023 - June 2023 2,115 ​ $ 10.00 - $18.75 (1) July 2023 80 ​ $ 10.00 (1) October 2023 100 ​ $ 10.00 (1) Private and public warrants 23,830 ​ $ 11.50 ​ March 26, 2029 Tota l 26,724 ​ ​ (1) Within 3 years from the date of issuance. See Note 3 with respect to further details on the private and public warrants and Note 5 with respect to valuation techniques and assumptions because the warrants are all liability-classified and subject to fair value measurement each reporting period.	8. Warrants Stock Warrants The Company has issued stock purchase warrants (the “Warrants”). The Warrants entitle the holder to purchase a specified number of shares of the Company’s common stock or new series of preferred stock at a specified price. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Issued Exercised Expired/ Outstanding ​ ​ ​ ​ ​ ​ Cancelled ​ ​ December 2020 (*1) 2,514,285 — (2,514,285) — February 2021 (*2) 342,857 — (342,857) — August 2021 (*3) 999,997 — — 999,997 September 2021 (*3) 428,571 — — 428,571 February 2023 ~ June 2023 (*7) (*9) 7,685,717 (428,572) — 7,257,145 July 2023 (*7) 228,572 — — 228,572 October 2023 (*7) 285,715 — — 285,715 ​ ​ ​ ​ ​ ​ ​ ​ ​ Exercise Price Expiration December 2020 (*1) ​ $ 3.50 (*5) Earlier of within 2 years from the date of issuance or 2 weeks before U.S. IPO or Korea IPO February 2021 (*2) ​ $ 3.50 (*4) Within 18 months from the date of issuance August 2021 (*3) ​ $ 3.50 (*6) Within 3 years from the date of issuance September 2021 (*3) ​ $ 3.50 (*5) Within 3 years from the date of issuance February 2023 ~ June 2023 (*7) (*9) ​ $ 3.50 (*8) Within 3 years from the date of issuance July 2023 (*7) ​ $ 3.50 (*10) Within 3 years from the date of issuance October 2023 (*7) ​ $ 3.50 (*10) Within 3 years from the date of issuance (*1) (*2) (*3) (*4) (*5) (*6) (*7) (*8) (*9) (*10) During the year ended December 31, 2023, warrants were exercised for 428,572 common shares. The number of warrants outstanding as of December 31, 2023 were 9,200,000 shares.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Stock-Based Compensation
Stock-Based Compensation	11. Stock-Based Compensation 2011 Incentive Compensation Plan Legacy GCT’s 2011 Incentive Compensation Plan (the “2011 Plan”) permitted the grant of options, stock awards, and RSUs. In connection with the Closing of the Business Combination, the 2011 Plan was terminated, the remaining unallocated shares reserved under the 2011 Plan were cancelled and no new awards will be granted under the 2011 Plan. Each award of Legacy GCT stock options and RSUs were converted into equivalent Company stock options and RSUs with the same terms and conditions under the plan described below. 2024 Incentive Compensation Plan In connection with the Closing of the Business Combination, the Company adopted the 2024 Incentive Compensation Plan (the “2024 Plan”) under which 3,983,334 shares of common stock were initially reserved for issuance, subject to approval by the Company’s boards of directors. The 2024 Plan permits the grant of stock options, stock appreciation rights, stock awards, restricted stock units, dividend equivalent right, cash awards and other awards to employees, non-employee directors, non-employee members of the board of directors, or consultants or independent advisors. Stock options outstanding under the 2024 Plan were as follows (in thousands, except per share amounts and years): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Number of ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ Options ​ Average ​ Contractual Life ​ Aggregated ​ ​ Outstanding ​ Exercise Price ​ (in Years) ​ Intrinsic Value Balance as of December 31, 2023 ​ 3,579 ​ $ 0.02 ​ 5.5 ​ $ 4,405 Reverse recapitalization ​ (2,911) ​ ​ 0.09 ​ — ​ ​ — Balance as of December 31, 2023 (1) ​ 668 ​ ​ 0.11 ​ 5.5 ​ ​ 4,405 Granted ​ — ​ ​ — ​ — ​ ​ — Exercised ​ — ​ ​ — ​ — ​ ​ — Cancelled ​ — ​ ​ — ​ — ​ ​ — Balance as of March 31, 2024 668 $ 0.11 5.3 $ 5,543 Vested as of March 31, 2024 667 ​ $ 0.11 5.3 $ 5,532 Exercisable as of March 31, 2024 634 ​ $ 0.11 5.1 $ 5,256 (1) Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (see Note 3). There were no options granted during the three months ended March 31, 2024 and 2023. As of March 31, 2024, unrecognized compensation cost related to stock options was nominal. Founder Awards to Board of Directors In 2021, an aggregate of 90,000 founder shares of common stock were transferred to three members of Concord III’s board of directors. The shares contained both a performance condition based upon a liquidity event and a service vesting condition. As the liquidity and services conditions were met upon the Closing of the Business Combination, the Company recognized $0.9 million of stock-based compensation during the three months ended March 31, 2024. Restricted Stock Units In December 2023, various employees and directors of Legacy GCT were granted RSUs that contain both a performance condition based upon a liquidity event and a service vesting condition such that the RSUs vest in four equal annual installments from the grant date. Any unvested RSUs are forfeited upon separation from the Company. The liquidity condition was met upon the Closing of the Business Combination and the Company recognized $0.3 million of stock-based compensation. RSUs outstanding under the 2024 Plan were as follows (in thousands, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of RSUs ​ Average Grant ​ ​ Outstanding ​ Date Fair Value Balance as of December 31, 2023 ​ 2,100 ​ $ 1.15 Reverse recapitalization ​ (1,708) ​ ​ 5.01 Balances as of December 31, 2023 (1) ​ 392 ​ $ 6.16 Granted — ​ — Vested — ​ — Cancelled — ​ — Balance as of March 31, 2024 392 ​ $ 6.16 (1) Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (see Note 3). As of March 31, 2024, there was $2.1 million of unrecognized compensation cost related to RSUs, which is expected to be recognized on a straight-line basis over a weighted average period of 3.7 years.	9. Stock-Based Compensation In September 2011, the Board of Directors adopted the 2011 Incentive Compensation Plan (the “2011 Plan”). The Company reserved 6,277,777 shares of common stock for issuance under the 2011 Plan. Such share reserve is comprised of (i) the number of shares that were available for issuance in the aggregate under prior option plans on the effective date of the 2011 Plan, including the shares subject to outstanding awards under those plans, that were transferred to the new 2011 Plan on the effective date, plus (ii) an additional 265,597 shares of the Company’s common stock so that the initial total shares reserve is 6,277,777. The share reserve will automatically increase on the first trading day of January each calendar year during the term of the 2011 Plan, beginning with calendar year 2012, by an amount equal to 5% of the total number of shares of common stock outstanding on the last trading day in the immediately preceding calendar month. In no event, however, will any such annual increase exceed 2,500,000 shares, and the Board of Directors may decide to waive the automatic increase. The Board of Directors waived the automatic increase of share reserve in 2022 and 2023. In September 2021, the Board of Directors approved the amendment of 2011 Plan to extend the termination of the 2011 Plan to September 11, 2031. Stock Options Option activities for the periods presented are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Number of ​ ​ ​ ​ Average ​ ​ Shares ​ Stock ​ Weighted- ​ Remaining ​ ​ Available ​ Options ​ Average ​ Contractual Life ​ for Grant Outstanding Exercise Price (Years) Balances as of January 1, 2022 ​ 1,679,763 ​ ​ 8,194,822 ​ $ 0.02 ​ 6.1 Granted (105,000) ​ 105,000 ​ 0.02 Exercised — ​ (2,459,014) ​ 0.02 Cancelled 1,066,916 ​ (1,066,916) ​ 0.02 Balances as of December 31, 2022 2,641,679 ​ 4,773,892 ​ 0.02 5.1 RSUs granted (2,099,970) ​ — ​ — Exercised — ​ (1,130,481) ​ 0.02 Cancelled 64,117 ​ (64,117) ​ 0.02 Balances as of December 31, 2023 605,826 ​ 3,579,294 ​ 0.02 5.5 Vested as of December 31, 2023 ​ ​ ​ 3,311,859 ​ $ 0.02 ​ 5.3 Vested and expected to be vest as of December 31, 2023 ​ ​ ​ 3,569,024 ​ $ 0.02 ​ 5.5 ​ The weighted average grant date fair value of options granted during the year ended December 31, 2022, was $0.01 per share. There were no options granted during the year ended December 31, 2023. As of December 31, 2023, there was $2,000 of unrecognized compensation cost related to employee stock option compensation arrangements which is expected to be recognized on a straight-line basis over a weighted average period of 1.3 years. There were no capitalized stock-based compensation costs or recognized stock-based compensation tax benefits during the years ended December 31, 2023 and 2022. ​ 9. Stock-Based Compensation, Determining Fair Value of Stock Options The fair value of each grant of stock options was determined by the Company and its Board of Directors using the methods and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment to determine. Valuation Method The Company estimates the fair value of its stock options using the Black-Scholes option-pricing model. Expected Term The expected term represents the period that the stock-based awards are expected to be outstanding. The option grants qualify to be “plain vanilla,” and the Company used the simplified method to determine the expected term. The simplified method calculates the expected term as the average of the time-to-vesting and contractual life of the option. Fair Value of Common Stock The fair value of the common stock underlying the stock options has historically been determined by the Company’s Board of Directors, with input from management. The Board of Directors is comprised of a majority of nonemployee directors with significant experience investing and operating companies in the semiconductor industry. As such, the Company believes that the Board of Directors has the relevant experience and expertise to determine a fair market value of the common stock on each respective grant date. Because there has been no public market for the Company’s common stock, the Board of Directors has determined the fair market value of the common stock at the time of the option grant by considering a number of objective and subjective factors including valuations of comparable companies, sales of convertible preferred stock to unrelated third parties, operating and financial performance, lack of liquidity of capital stock and general and industry-specific economic outlook, amongst other factors. The fair value of the underlying common stock shall be determined by the Board of Directors until such time that the Company’s common stock is listed on an established stock exchange or national market system. Risk-Free Interest Rate The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for zero coupon U.S. Treasury notes with maturities approximately equal to the expected term of the options. Expected Volatility The expected volatility was based on the historical stock volatilities of several of the Company’s publicly listed peers over a period approximately equal to the expected term of the options as the Company did not have a sufficient trading history to use the volatility of its own common stock. Expected Dividend Yield The expected dividend yield has been zero as the Company has never paid dividends on common stock and does not expect to pay dividends on common stock. ​ 9. Stock-Based Compensation, Determining Fair Value of Stock Options, Forfeiture Rate The Company estimates its forfeiture rate based on an analysis of its actual forfeitures and will continue to evaluate the adequacy of the forfeiture rate based on actual forfeiture experience, analysis of employee turnover behavior and other factors. The impact from a forfeiture rate adjustment will be recognized in full in the period of adjustment, and if the actual number of future forfeitures differs from that estimated, the Company may be required to record adjustments to stock-based compensation expense in future periods. Summary of Assumptions The fair value of the employee stock options were estimated on the grant dates using a Black-Scholes option-pricing model with the following weighted average assumptions: ​ ​ ​ ​ ​ ​ 2022 Estimated term (in years) 5.8 ​ Risk-free interest rate 1.85 % Expected volatility 65 % Expected dividend yield 0 % ​ Restricted Stock Units Restricted Stock Units (“RSUs”) granted to employees and board members under 2011 Plan vest over 4 years RSUs activities for the fiscal year ended December 31, 2023, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of ​ Average Grant ​ Shares Date Fair Value Nonvested, outstanding at December 31, 2022 — ​ $ — Granted 2,099,970 ​ 1.15 Vested — ​ — Cancelled — ​ — Nonvested, outstanding at December 31, 2023 2,099,970 ​ $ 1.15 ​ As of December 31, 2023, there was $1,990,000 of unrecognized compensation cost related to RSUs, which is expected to be recognized on a straight-line basis over a weighted average period of 3.95 years.

Income Taxes

Income Taxes	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Income Taxes
Income Taxes	12. Income Taxes For the three months ended March 31, 2024 and 2023, the Company recorded income tax expense of $59,000 and $50,000, respectively. The effective tax rate is 7.2% and 3.7% for the three months ended March 31, 2024 and 2023, respectively. For financial reporting purposes, the Company’s effective tax rate used for the interim periods is based on the estimated full-year income tax rate. For the three months ended March 31, 2024, the Company’s effective tax rate differs from the statutory rate primarily due to the valuation allowance recorded against the net deferred tax asset balance. As of March 31, 2024 the Company had unrecognized tax benefits of $3.1 million of which $1.7 million would currently affect the Company’s effective tax rate if recognized due to the Company’s deferred tax assets being fully offset by a valuation allowance. The Company does not anticipate that the amount of unrecognized tax benefits relating to tax positions existing as of March 31, 2024 will significantly increase or decrease within the next twelve months. There was no interest expense or penalties related to unrecognized tax benefits recorded as of March 31, 2024. A number of years may elapse before an uncertain tax position is audited and finally resolved. While it is often difficult to predict the final outcome or the timing of resolution of any particular uncertain tax position, the Company believes that its reserves for income taxes reflect the most likely outcome. The Company adjusts these reserves, as well as the related interest, in light of changing facts and circumstances. Settlement of any particular position could require the use of cash. Currently the Company is not under examination by any taxing authority.	10. Income Taxes Determining the provision for income taxes, income taxes payable, and deferred tax assets and liabilities involves judgment. The Company calculates and provides for income taxes in each of the tax jurisdictions in which it operates, which involves estimating current tax exposures as well as making judgments regarding the recoverability of deferred tax assets in each jurisdiction. The estimates used could differ from actual results, and this may have a significant impact on financial position, operating results and cash flows in future periods. 10. Income Taxes, continued The domestic and foreign components of income (loss) before provision for income taxes were as follows for the years ended December 31: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Domestic ​ $ (19,910) ​ $ (30,559) Foreign ​ (2,018) ​ 4,268 Loss before provision for income taxes ​ $ (21,928) ​ $ (26,291) ​ ​ The provision for income taxes for the years ended December 31, 2023 and 2022 consisted of the following: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Current ​ ​ Federal ​ $ 215 ​ $ 128 State ​ 1 ​ 1 Foreign ​ 325 ​ (8) Total current ​ 541 ​ 121 ​ ​ ​ ​ ​ ​ ​ Deferred ​ ​ Federal ​ — ​ — State ​ — ​ — Foreign ​ — ​ — Total deferred ​ — ​ — Total provision for income taxes ​ $ 541 ​ $ 121 ​ The reconciliation of federal statutory income tax to the Company’s provision for income taxes is as follows: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Expected benefit at statutory federal rate ​ $ (4,941) ​ $ (6,717) State tax — net of federal benefit ​ 72 ​ 100 Research and development credits ​ — ​ (564) Foreign income/losses taxed at different rates ​ 14 ​ 15 Unrecognized tax benefits ​ 276 ​ 126 Stock-based compensation ​ 8 ​ 3 Interest expense ​ 333 ​ 233 Remeasurements of net defined benefit liabilities ​ 5 ​ — Exchange rate difference ​ 287 ​ 551 Change in tax rate ​ (242) ​ (92) True-up deferred taxes ​ 1,382 ​ 3,254 True-up payable ​ 75 ​ — Accumulated deficit ​ 67 ​ 10 Change in valuation allowance ​ 3,182 ​ 3,246 Other ​ 23 ​ (44) Total provision for income taxes ​ $ 541 ​ $ 121 ​ ​ 10. Income Taxes, For the years ended December 31, 2023 and 2022, the Company’s provision for income taxes differed from the federal statutory tax rate due primarily to the full valuation allowance for federal and state purposes, true-up deferred taxes, research and development credits, and exchange rate differences. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Deferred tax assets ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 79,078 ​ $ 78,583 Capitalized costs ​ 5,409 ​ 3,095 Accruals and reserves ​ 4,610 ​ 4,830 Inventory reserves ​ 267 ​ 402 Stock compensation ​ 382 ​ 368 Loss on unrealized currency translation ​ 166 ​ 160 Research and development credits ​ 2,490 ​ 2,490 Financial guarantee liabilities ​ 5,410 ​ 5,320 Lease liability ​ 197 ​ 4 Provision for credit losses ​ 368 ​ 119 Gross deferred tax assets ​ 98,377 ​ 95,371 Valuation allowance ​ (97,628) ​ (94,446) Net deferred tax assets ​ 749 ​ 925 Deferred tax liabilities ​ ​ ​ ​ ​ ​ Revaluation of convertible promissory notes ​ (448) ​ (742) Contract assets ​ (3) ​ (8) ROU assets ​ (298) ​ (175) Gross deferred tax liabilities ​ (749) ​ (925) Net deferred income tax ​ $ — ​ $ — ​ The Company provided a valuation allowance for net operating losses, credits and other deferred tax assets of its United States and foreign entities. A valuation allowance is provided when, based upon the available evidence, management concludes that it is more-likely-than-not that some portion of the deferred tax assets will not be realized. The Company maintained a valuation allowance as of December 31, 2023 and 2022 due to the uncertainty of realizing future tax benefits from its net operating loss carryforwards and other deferred tax assets. The valuation allowance increased by $3.2 million for both the years ended December 31, 2023 and 2022, respectively. The Company had net operating loss carryforwards (“NOL”) for federal, state and foreign income tax purposes of approximately $334 million, $49 million and $27 million, respectively, as of December 31, 2023. State NOL will begin to expire in 2028 and $123 million of the Company’s federal NOL will last indefinitely (limited to 80% of taxable income in a given year). As of December 31, 2023, the Company had federal and state research credit carryforwards of approximately $2.4 million and $2.3 million, respectively. The federal research credit carryforwards will begin to expire in 2025 while the California research credits carryforward have an indefinite life. ​ 10. Income Taxes, ​ Section 382 of the Internal Revenue Code of 1986, as amended, imposes restrictions on the utilization of NOL carryforwards and research tax credits in the event of a change in ownership. While the Company believes that it is probable that its ability to utilize NOL carryforwards may be limited due to past ownership changes, the Company has not yet completed an analysis to determine the amount of such limitation, if any. A reconciliation of the unrecognized tax benefits (“UTBs”) as of December 31, 2023 and 2022 is as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Beginning gross UTBs ​ $ 3,203 ​ $ 3,106 Additions for tax positions taken in a prior year ​ — ​ (35) Additions for tax provision taken in the current year ​ 319 ​ 1,093 Adjustments for tax positions for changes in currency translation ​ 95 ​ (223) Reductions for tax positions taken in the prior year ​ 1,051 ​ (270) Reductions for tax positions taken in the prior year due to statutes lapsing ​ (1,585) ​ (468) Ending gross UTBs ​ 3,083 ​ 3,203 UTBs offset by deferred tax assets and/or valuation allowance ​ (1,419) ​ (1,714) Net UTBs ​ $ 1,664 ​ $ 1,489 ​ As of December 31, 2023, the total amount of gross unrecognized tax benefits was $3.1 million. The amount of unrecognized tax benefits that, if recognized, would affect the Company’s effective tax rate is $1.7 million as of December 31, 2023. The remaining amounts in unrecognized tax benefits would not impact the rate as they are offset by valuation allowances. As of December 31, 2023 and 2022, accrued interest and penalties were $522,000 and $449,000, respectively. The Company recognizes interest and penalties related to unrecognized tax benefits within the provision for income taxes line in the accompanying consolidated statements of operations. Accrued interest and penalties are included within the related tax liability line in the consolidated balance sheets. The Company has classified the unrecognized tax benefits as long term, as it does not expect them to be realized over the next 12 months. The Company also does not expect its unrecognized tax benefits to change significantly over the next 12 months. The Company files income tax returns in the U.S. federal jurisdiction, California and in many foreign jurisdictions. The Company’s tax years for 2020 and forward are subject to examination by the U.S. tax authorities. The Company’s tax years for 2019 and forward are subject to examination by various state tax authorities. However, due to the fact that the Company had loss and credits carried forward in some jurisdictions, certain items attributable to technically closed years are still subject to adjustment by the relevant taxing authority through an adjustment to tax attributes carried forward to open years. The Company files U.S. and foreign income tax returns with varying statutes of limitations. Due to the Company’s net carryover of unused operating losses, all years remain subject to future examination by tax authorities.

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Employee Benefit Plans
Employee Benefit Plans	13. Employee Benefit Plans Under Korean law, the Company is required to make severance payments to Korean employees leaving its employment. The Company’s severance pay liability to its Korean employees, which is a function of the salary of each employee’s years of employment and severance factor, is reflected in the accompanying condensed consolidated balance sheets as the net defined benefit liabilities on an accrual basis. The net liability for severance payments as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 Liability for severance payments, beginning ​ $ 7,764 ​ $ 7,997 Deposit ​ (276) ​ (308) Liability for severance payments, ending ​ $ 7,488 ​ $ 7,689 ​	11. Employee Benefit Plans The Company sponsors a 401(k) defined contribution plan covering all U.S. employees. Contributions made by the Company are determined annually by the Board of Directors. Employer contributions under this plan amounted to $64,000 and $71,000 for the years ended December 31, 2023 and 2022, respectively. Under Korean law, the Company is required to make severance payments to Korean employees leaving its employment. The Company’s severance pay liability to its Korean employees, which is a function of the salary of each employee’s years of employment and severance factor, is reflected in the accompanying consolidated balance sheets as net defined benefit liabilities on an accrual basis. As of December 31, 2023 and 2022, the net liability for severance payments consisted of: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Liability for severance payments ​ $ 7,997 ​ $ 7,248 Deposit ​ (308) ​ (343) ​ ​ $ 7,689 ​ $ 6,905 ​

Related Party Transactions

Related Party Transactions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Related Party Transactions
Related Party Transactions	14. Related Party Transactions A summary of balances and transactions with the related parties who are stockholders of the Company were as follows as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 ​ ​ Anapass Kyeongho Lee ​ Anapass Kyeongho Lee Borrowings ​ $ 9,653 ​ $ 824 ​ $ 10,082 ​ $ 1,474 Other current liabilities ​ 106 ​ 87 ​ 212 ​ 182 ​ For each of the three months ended March 31, 2024 and 2023, the Company recorded $0.1 million of interest expense with Anapass, Inc. in the condensed consolidated statements of operations. During the three months ended March 31, 2024 and 2023, the Company recorded $22,000 and $26,000, respectively, of interest expense with Kyeongho Lee in the condensed consolidated statements of operations.	12. Related Party Transactions A summary of balances and transactions with the related parties who are stockholders of the Company as of and for the years ended December 31, 2023 and 2022, are approximately as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ 2023 ​ 2022 ​ Anapass Kyeongho Lee Anapass Kyeongho Lee Borrowings ​ $ 10,082 ​ $ 1,474 ​ $ 10,257 ​ $ 1,690 Other current liabilities ​ 212 ​ 182 ​ 11 ​ 150 Interest expense ​ 548 ​ 110 ​ 389 ​ 140 ​

Segments and Information

Segments and Information	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Segments and Information
Segments and Information	15. Segments and Information The Company operates in one segment. Revenue information by geographic region is presented in Note 4 to these condensed consolidated financial statements. Long-lived assets by geographic region were as follows as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 South Korea ​ $ 1,170 ​ $ 1,363 United States ​ 817 ​ 930 Total long-lived assets ​ $ 1,987 ​ $ 2,293 ​	13. Segments and Geographical Information The Company operates in one segment. Revenue information by geographic region is presented in Note 1 to these consolidated financial statements. Long-lived assets by geographic region for the years ended December 31, 2023 and 2022 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 United States ​ $ 930 ​ $ 1,295 South Korea ​ 1,363 ​ 626 Total long-lived assets ​ $ 2,293 ​ $ 1,921 ​

Net Income (Loss) Per Share

Net Income (Loss) Per Share	3 Months Ended
	Mar. 31, 2024
Net Income (Loss) Per Share
Net Income (Loss) Per Share	16. Net Income (Loss) Per Share The following table summarizes the computation of basic and diluted net income (loss) per share (in thousands, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Numerator: ​ ​ Net income (loss), basic and diluted ​ $ 757 ​ $ (1,393) Denominator: ​ ​ Weighted-average common shares outstanding, basic ​ 25,468 ​ 23,862 Add: effect of dilutive securities ​ 789 ​ — Weighted-average common shares outstanding, diluted ​ 26,257 ​ 23,862 Net income (loss) per share, basic and diluted ​ ​ Basic ​ $ 0.03 ​ $ (0.06) Diluted ​ $ 0.03 ​ $ (0.06) ​ The following outstanding potentially dilutive common stock equivalents were excluded from the computation of diluted net income (loss) per share for the periods indicated because including them would have been antidilutive (in thousands): ​ ​ ​ ​ ​ ​ March 31, ​ ​ 2024 2023 Warrants 26,724 995 Convertible promissory notes 5,543 1,809 Options — 885 Total 32,267 3,689 ​

Subsequent Events

Subsequent Events	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Subsequent Events
Subsequent Events	17. Subsequent Events Purchase Agreement and Registration Rights Agreement In April 2024, the Company entered into a common stock purchase agreement (the “Purchase Agreement”) and a related registration rights agreement (the “Registration Rights Agreement”) with B. Riley Principal Capital II, LLC (“B. Riley Principal Capital II”). Upon the terms and subject to the satisfaction of the conditions set forth in the Purchase Agreement, the Company has the right, in its sole discretion, to sell to B. Riley Principal Capital II, from time to time, up to $50.0 million in aggregate gross purchase price of shares of the Company’s common stock, subject to certain limitations contained in the Purchase Agreement, during the term of 24 months M-Venture Investment, Inc. In April 2024, the Company executed an amendment with M-Venture Investment, Inc. for the KRW 4.0 billion ($3.0 million) term loan outstanding, pursuant to which the Company repaid KRW 2.0 billion ($1.5 million) in April 2024 and extended the maturity date from October 2024 to May 2024 (see Note 7). In April 2024, the Company executed an amendment with M-Venture Investment, Inc. for the KRW 6.0 billion ($4.4 million) term loan outstanding, pursuant to which the maturity date for both draws were amended. The maturity date for the principal amount of KRW 1.0 billion ($0.7 million) was extended from April 2024 to June 2024. The maturity date for the principal amount of KRW 5.0 billion ($3.7 million) was extended from April 2024 to July 2024 (see Note 7). Historical Convertible Promissory Notes In April 2024, the Company repaid in full a historical convertible promissory note that was issued in 2021 with a principal amount of $0.6 million (see Note 7). Share Reserve In May 2024, the board of directors of the Company approved 3,983,334 shares as the maximum number of shares of Common Stock that may be issued pursuant to 2024 Plan, and 600,000 shares as reserved share amount of 2024 Employee Stock Purchase Plan.	14. Subsequent Events Management has evaluated all transactions and events through March 29, 2024, the date on which these consolidated financial statements were available to be issued, and other than the following there are no other items that would adjust the consolidated financial statements or require additional disclosures. In January 2024, the maturity date of the loan of $776,000 from i Best Investment was extended for two three In January 2024, GCT R&D, a subsidiary of the Company, borrowed a short term loan of $237,000 from NJ Holdings, a related party. The loan had a seven In January, February and March 2024, GCT R&D repaid term loan of $613,000 to Kyeongho Lee. In February and March 2024, the Company issued convertible promissory notes of $11.3 million to Korean investors. The convertible promissory notes mature in February and March 2027 and have a conversion price of $6.67 per share. The convertible promissory notes will be automatically converted to common stock upon the closing of the transaction with Concord Acquisition Corp III discussed in Note 1. In February 2024, the Company issued a convertible promissory note of $5.0 million to a U.S. company. The convertible promissory note matures in February 2026 and has a conversion price of $10.00 per share. The convertible promissory note holder can demand conversion to common stock on or after the earlier of i) completion of the SPAC transaction and ii) six On March 15, 2024, the Board of Directors approved a term sheet of equity line of credit (ELOC) facility proposed by an investment banking firm. Under this facility, the Company may issue and sell shares common stock, from time to time, to an affiliate of the investment banking firm at a price equal to a specified percentage of VWAP (Volume Weighted Average Price) of the stock on NYSE up to an aggregate amount of $50 million. The term sheet is not binding and subject to completion of definitive agreements, and the Board of Directors delegated authority to the management to negotiate and finalize definitive agreements for the facility. On March 26, 2024, Concord Acquisition Corp III consummated its Business Combination with the Company, pursuant to the Business Combination Agreement, dated as of November 2, 2023, and changed name to GCT Semiconductor Holding, Inc. (“GCT Holding”). On March 26, 2024, in accordance with the terms of the Business Combination Agreement, the Company’s all outstanding warrants were assumed by GCT Holding. On March 26, 2024, the Company terminated the 2011 Plan. As a result, all outstanding options and RSUs under the 2011 Plan were assumed by GCT Holding in accordance with the terms of the Business Combination Agreement. On March 26, 2024, the convertible promissory notes (“CPN”) principal and related accrued interest balance of $32,087,000 and the convertible notes to SPAC shares (“CVT”) principal and related accrued interest balance of $13,370,000 were converted into 4,258,223 and 2,004,535 shares of GCT Holding common stock, respectively. On March 26, 2024, as consideration for the $30.2 million PIPE Financing, the Company issued 4,529,967 shares of GCT Holding common stock to PIPE Shareholders.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies and Basis of Presentation (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Summary of Significant Accounting Policies and Basis of Presentation
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation The condensed consolidated financial statements and accompanying notes include the accounts of the Company and its wholly owned subsidiaries, after elimination of intercompany balances and transactions. The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the requirements of the Securities and Exchange Commission (“SEC”) for interim financial information. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the year ended December 31, 2023, which are included in the Company’s Form 8-K filed with the SEC on April 1, 2024. The information as of December 31, 2023 included in the condensed consolidated balance sheets was derived from those audited consolidated financial statements. The unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial information. The condensed consolidated results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results to be expected for the year ending December 31, 2024 or for any other future annual or interim period.
Use of Estimates	Use of Estimates The preparation of the accompanying condensed consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates, and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. These judgments, estimates and assumptions are used for but not limited to revenue recognition, provision for credit losses, inventory obsolescence, recoverability of long-lived assets, certain accrued expenses, stock-based compensation, determination of fair value of the Company’s convertible promissory notes, common stock (prior to the reverse recapitalization), warrant labilities and stock options, and deferred income taxes including related valuation allowances. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates, and these differences may be material.	Use of Estimates The preparation of the accompanying consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates, and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. These judgments, estimates and assumptions are used for but not limited to: revenue recognition; provision for credit losses; warranty obligations; inventory obsolescence; recoverability of long-lived assets; stock-based compensation; determination of fair value of the Company’s convertible promissory notes, common stock, and stock options, and deferred income taxes including related valuation allowances. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates, and these differences may be material.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amount of certain financial instruments held by the Company, such as cash equivalents, accounts receivable, contract assets and liabilities, accounts payable, and accrued and other current liabilities, approximate fair value due to their short maturities. The carrying amount of the liabilities for the convertible promissory notes represents their fair value. The carrying amounts of the Company’s bank borrowings and lease liabilities approximate fair value due to the market interest rates that these obligations bear and interest rates available to the Company. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s Level 3 financial instruments consist of convertible promissory notes and warrant liabilities. These financial instruments were valued using valuation techniques that are considered to be a Level 3 fair value measurement .	Fair Value of Financial Instruments The carrying amount of certain financial instruments held by the Company, such as cash equivalents, accounts receivable, contract assets and liabilities, accounts payable, and accrued and other current liabilities, approximate fair value due to their short maturities. The carrying amount of the liabilities for the convertible promissory notes represents their fair value. The carrying amounts of the Company’s bank borrowings, and lease liabilities approximate fair value due to the market interest rates that these obligations bear and interest rates currently available to the Company. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities; Level 2 Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company has no assets with fair value obtained using observable or unobservable markets. The Company did have liabilities with a fair value obtained using unobservable markets (Level 3). The Company’s Level 3 liabilities consist of the redeemable convertible preferred stock warrant liabilities and convertible promissory notes. The convertible promissory notes were valued using a combination of option pricing model and Probability Weighted Expected Return Method (“PWERM”), which is considered to be a Level 3 fair value measurement.
Risk and Uncertainties	Risk and Uncertainties The Company is subject to certain risks and uncertainties and believes changes in any of the following areas could have a material adverse effect on the Company’s future financial position or results of operations or cash flows: new product development, including market receptivity, the ability to satisfy obligations under development agreements with major partners, litigation or claims against the Company based on intellectual property, patent, product regulation or other factors, competition from other products, general economic conditions, the ability to attract and retain qualified employees and ultimately to sustain profitable operations. The semiconductor industry is characterized by rapid technological change, competition, competitive pricing pressures and cyclical market patterns. The Company’s financial results are affected by a wide variety of factors, such as general economic conditions specific to the semiconductor industry and the Company’s particular market, the timely implementation of new products, new manufacturing process technologies and the ability to safeguard patents and intellectual property in a rapidly evolving market. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns. As a result, the Company may experience significant period-to-period fluctuations in condensed consolidated operating results due to the factors mentioned above or other factors. The Company’s revenue may be impacted by its ability to obtain adequate wafer supplies from foundries and back-end production capacity from the Company’s test and assembly subcontractors. The foundries with which the Company currently has arrangements may not be willing or able to satisfy all of the Company’s manufacturing requirements on a timely basis and/or at favorable prices. The Company is also subject to the risks of service disruptions, raw material shortages and price increases by its foundries. Such disruptions, shortages and price increases could harm the Company’s consolidated operating results.	Risk and Uncertainties The Company is subject to certain risks and uncertainties and believes changes in any of the following areas could have a material adverse effect on the Company’s future financial position or results of operations or cash flows: new product development, including market receptivity, litigation or claims against the Company based on intellectual property, patent, product regulation or other factors, competition from other products, general economic conditions, the ability to attract and retain qualified employees and ultimately to sustain profitable operations. The semiconductor industry is characterized by rapid technological change, competition, competitive pricing pressures and cyclical market patterns. The Company’s financial results are affected by a wide variety of factors, such as general economic conditions specific to the semiconductor industry and the Company’s particular market, the timely implementation of new products, new manufacturing process technologies and the ability to safeguard patents and intellectual property in a rapidly evolving market. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns. As a result, the Company may experience significant period-to-period fluctuations in consolidated operating results due to the factors mentioned above or other factors. The Company’s revenue may be impacted by its ability to obtain adequate wafer supplies from foundries and back-end production capacity from the Company’s test and assembly subcontractors. The foundries with which the Company currently has arrangements may not be willing or able to satisfy all of the Company’s manufacturing requirements on a timely basis and/or at favorable prices. The Company is also subject to the risks of service disruptions, raw material shortages and price increases by its foundries. Such disruptions, shortages and price increases could harm the Company’s consolidated operating results.
Provision for Credit Losses	Provision for Credit Losses The provision for credit losses is based on the Company’s assessment of the collectability of its customer accounts. The Company reviews the provision for credit losses by considering certain factors such as historical experience, industry data, credit quality, age of balances and current economic conditions that may affect a customer’s ability to pay. Uncollectible receivables are written off when all efforts to collect have been exhausted and recoveries are recognized when they are recovered. The Company determined that provisions for credit losses of approximately $1.9 million and $1.6 million were necessary as of March 31, 2024 and December 31, 2023, respectively.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to the concentration of credit risk consist of cash and cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents primarily with one financial institution located in the United States and another financial institution located in Korea where amounts deposited may exceed Federal Deposit Insurance Corporation or Korea Deposit Insurance Corporation limits. The Company’s accounts receivable balances are primarily derived from revenues earned from customers located in the United States, China, Korea, Japan and Taiwan. The Company performs ongoing credit evaluations of its customers’ and distributors’ financial condition and generally does not require collateral from its customers. The Company’s net revenue and accounts receivable are concentrated among a few significant customers, which could expose the Company to financial risk in the event of adverse developments with these customers. Four customers accounted for approximately 28 percent, 19 percent, 18 percent and 13 percent of the Company’s gross accounts receivable as of March 31, 2024. Four customers accounted for approximately 27 percent, 19 percent, 14 percent and 10 percent of the Company’s gross accounts receivable as of December 31, 2023. Two customers accounted for approximately 61 percent and 24 percent of the Company’s total net revenues for the three months ended March 31, 2024. Four customers accounted for approximately 28 percent, 28 percent, 25 percent, and 10 percent of the Company’s total net revenues for the three months ended March 31, 2023. Management closely monitors the creditworthiness and performance of these key customers and has established credit limits and terms to mitigate potential credit risks. The Company also continues to diversify its customer base and explore opportunities to reduce its reliance on a few major customers.	Concentration Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash and cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents primarily with one financial institution located in the United States and another financial institution located in Korea where amounts deposited may exceed Federal Deposit Insurance Corporation or Korea Deposit Insurance Corporation limits. The Company’s accounts receivable are primarily derived from revenues earned from customers located in the United States, China, Korea, Japan and Taiwan. The Company performs ongoing credit evaluations of its customers’ and distributors’ financial condition and generally does not require collateral from its customers. Some of the components used in the Company’s products are purchased from a limited number of sources located in Asia. The loss of any of these suppliers may cause the Company to incur additional costs to transition these relationships, result in delays in the delivery of its products or cause the Company to carry excess or obsolete inventory. GCT is a fabless semiconductor company and relies on third parties for all of its manufacturing operations, including wafer fabrication, assembly, testing, warehousing, and shipping and logistics. The Company relies on UMC Company (USA) (“UMC”) and Samsung Semiconductor System LSI Division to manufacture substantially all of the wafers for its products. The Company uses third-party vendors to assemble, package and test the products. The Company primarily uses the services of Tianshui Huatian Co., Ltd., ATSemicon Co., Ltd. Amkor, and STATS ChipPAC Ltd. for assembly, and Advanced Semiconductor and Engineering, Inc. and Giga Solution Tech Co., Ltd. for testing. The Company depends on these third-party vendors to supply services and material of a requested quantity in a timely manner that meets the Company’s standards for yield, cost and manufacturing quality. The Company does not have long-term supply agreements with its third-party vendors other than a framework agreement with UMC. If one or more of these vendors terminates its relationship with the Company, or if the Company encounters any problems with its manufacturing supply chain, it could adversely impact the Company’s ability to ship products to its customers on time and in the quantity required, which in turn could cause an unanticipated decline in sales and possibly damage customer relationships.
Foreign Currency	Foreign Currency Financial statements of foreign subsidiaries that use the local currency as their functional currency are translated into U.S. dollars at the end-of-period exchange rates or at historical exchange rates for purposes of consolidation. Revenues and expenses are translated using average exchange rates during the period. Translation adjustments are included in accumulated other comprehensive loss within stockholders’ deficit. Gains and losses resulting from transactions denominated in a currency other than the functional currency are included in other income, net in the condensed consolidated statements of operations. The Company recognized $1.1 million and $0.7 million foreign currency exchange gains for the three months ended March 31, 2024 and 2023, respectively.	Foreign Currency Translation The Company’s foreign subsidiaries, located in Korea, use the local currency, or Korean won (“KRW”), as their functional currency. Financial statements of the foreign subsidiaries are translated into U.S. dollars at the end-of-period exchange rates except for capital stock issued, capital accounts and accumulated deficit which are translated at historical exchange rates for purposes of consolidation. Revenues and expenses are translated using average exchange rates prevailing during the period. Translation adjustments are included in accumulated other comprehensive income (loss) within stockholders’ deficit. Gains and losses resulting from transactions denominated in a currency other than the functional currency are included in other income (expense), net in the consolidated statements of operations. The Company recognized foreign currency exchange gains and losses for the years ended December 31, 2023 and 2022 presented as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Foreign currency gain, net ​ $ 265 ​ $ 181
Convertible Promissory Notes	Convertible Promissory Notes The Company has elected the fair value option to account for its outstanding convertible promissory notes. Under the fair value option, the convertible promissory notes must be recorded at their initial fair value on the date of issuance, any modification, and at the end of each reporting period end date thereafter. Changes in the estimated fair value of the convertible promissory notes are recognized as non-cash gains or losses in other income, net in the condensed consolidated statements of operations.	Convertible Promissory Notes The Company accounts for its convertible promissory notes under ASC 815, Derivatives and Hedging. According to ASC 815-15-25, an election can be made at the inception of a financial instrument to account for the instrument under the fair value option as per ASC 825, Financial Instruments. The Company has made such an election for its convertible promissory notes. Under the fair value option, the convertible promissory notes must be recorded at their initial fair value on the date of issuance, any modification, and each balance sheet date thereafter. Changes in the estimated fair value of the convertible promissory notes are recognized as non-cash gains or losses in other income (expense), net in the consolidated statements of operations.
Contracts in Equity	Contracts in Equity The Company classifies contracts in equity, including warrants to purchase shares of the Company’s common stock, that do not meet the indexation guidance as liabilities. At the end of each reporting period, such liability classified instruments are remeasured and changes in fair value during the reporting period are recognized within the condensed consolidated statements of operations until the earlier of the exercise, settlement, or expiration. The Company classifies contracts in equity, including the Legacy GCT Earnouts and Sponsor Earnouts (discussed in Note 3), that meet the indexation and equity classification guidance as a component of stockholders’ deficit and are not subject to fair value remeasurements.
Emerging Growth Company Status	Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS” Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these condensed consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.
Recent Accounting Pronouncements Adopted	Recent Accounting Pronouncements Adopted In August 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) Contracts in Entity’s Own Equity (Subtopic 815-40) In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805) Company adopted this guidance effective January 1, 2024, and noted no material impact on the Company’s condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820) In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740)	Recent Accounting Pronouncements In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”) which significantly changes the way entities recognize impairment of many financial assets by requiring immediate recognition of estimated credit losses expected to occur over their remaining life, instead of when incurred. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments–Credit Losses, which amends Subtopic 326-20 (created by ASU 2016-13) to explicitly state that operating lease receivables are not in the scope of Subtopic 326-20. Additionally, in April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments; in May 2019, the FASB issued ASU 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief; in November 2019, the FASB issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates, and ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses; and in March 2020, the FASB issued ASU 2020-03, Codification Improvements to Financial Instruments, to provide further clarifications on certain aspects of ASU 2016-13 and to extend the nonpublic entity effective date of ASU 2016-13. The changes (as amended) are effective for the Company for annual and interim periods in fiscal years beginning after December 15, 2022. The adoption of ASU 2016-13 did not have a material effect on the consolidated financial statements. In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity. ASU 2020-06 reduces the number of accounting models for convertible instruments and allows more contracts to qualify for equity classification. ASU 2020-06 is effective for the Company’s annual reporting periods beginning after December 15, 2023. Adoption is either a modified retrospective method or a fully retrospective method of transition. Early adoption is permitted, but no earlier than annual periods beginning after December 15, 2020. The Company is currently evaluating the effect the adoption of ASU 2020-06 will have on its consolidated financial statements. In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which provides an exception to fair value measurement for contract assets and contract liabilities related to revenue contracts acquired in a business combination. The ASU requires an entity (acquirer) to recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606. At the acquisition date, an acquirer should account for the related revenue contracts in accordance with Topic 606 as if it had originated the contracts. The ASU is effective for the Company for annual and interim periods in fiscal years beginning after December 15, 2023. Early adoption is permitted. The ASU is applied to business combinations occurring on or after the effective date. The Company is currently evaluating the effect the adoption of ASU 2021-08 will have on its consolidated financial statements. In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. The ASU clarifies that a contractual restriction on the sale of an equity security should not be considered in measuring the fair value of the equity security, and also cannot be recognized as a separate unit of account. The ASU also requires the investor to disclose the fair value of equity securities subject to contractual sale restrictions, the nature and remaining duration of the restriction(s), and the circumstances that could cause a lapse in the restriction(s). The ASU is effective for the Company for annual and interim periods beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the effect the adoption of ASU 2022-03 will have on its consolidated financial statements. In September 2022, the FASB issued ASU 2022-04, Liabilities—Supplier Finance Programs (Subtopic 405-50): Disclosure of Supplier Finance Program Obligations. The ASU requires a buyer of goods and services to disclose information about its supplier finance program obligations. This ASU is effective for annual and interim periods in fiscal years beginning after December 15, 2022, except for the rollforward disclosure, which is effective for annual and interim periods in fiscal years beginning after December 15, 2023, and annual periods thereafter. The amendments in this ASU are to be applied retrospectively to each period in which a balance sheet is presented, except for the rollforward disclosure, which is to be applied prospectively. The adoption of ASU 2022-04 did not have a material effect on the consolidated financial statements. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures, which expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. The updated standard is effective for annual periods beginning in fiscal 2025 and interim periods beginning in the first quarter of fiscal 2026. Early adoption is permitted. The Company is currently evaluating the effect the adoption of ASU 2023-07 will have on its consolidated financial statements. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740) – Improvements to Income Tax Disclosures, which requires companies to disclose, on an annual basis, specific categories in the effective tax rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold. In addition, companies are required to disclose additional information about income taxes paid. The standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The standard is to be adopted on a prospective basis; however, retrospective application is permitted. The Company is currently evaluating the effect the adoption of ASU 2023-09 will have on its consolidated financial statements.

Reverse Recapitalization (Table

Reverse Recapitalization (Tables)	3 Months Ended
	Mar. 31, 2024
Reverse Recapitalization
Number of shares of common stock issued and outstanding immediately following consummation of the Business Combination	The number of shares of common stock issued and outstanding immediately following consummation of the Business Combination was (in thousands): ​ ​ ​ ​ Shares Common stock of Concord III outstanding prior to the Business Combination 3,941 Less: redemption of Concord III’s common stock (3,766) Sponsor earnout common stock outstanding prior to the Business Combination 8,625 Common stock of Concord III issued and outstanding 8,800 Common stock issued in PIPE Financing 4,530 Legacy GCT common stock 32,503 Total common stock issued and outstanding 45,833

Disaggregation of Revenue (Tabl

Disaggregation of Revenue (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Organization and Liquidity
Schedule of disaggregation of revenues from contracts with customers and categorized by customer location	Disaggregation of revenues from contracts with customers is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2024 ​ Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ ​ At a point in time ​ $ 2,378 ​ $ — ​ $ 2,378 Over time ​ — ​ 887 ​ 887 Total ​ $ 2,378 ​ $ 887 ​ $ 3,265 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2023 ​ Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 599 ​ $ — ​ $ 599 Over time ​ — ​ 2,463 ​ 2,463 Total ​ $ 599 ​ $ 2,463 ​ $ 3,062 ​ Net revenues categorized by customer location are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ 2024 ​ 2023 Korea ​ $ 2,000 ​ $ — Germany ​ 796 ​ — United States ​ 389 ​ 1,968 China ​ 80 ​ 1,094 Total ​ $ 3,265 ​ $ 3,062	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2023 (in thousands) ​ Product Revenues ​ Service Revenues ​ Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 10,968 ​ $ — ​ $ 10,968 Over time ​ — ​ 5,060 ​ 5,060 Total ​ $ 10,968 ​ $ 5,060 ​ $ 16,028 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2022 (in thousands) Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 12,977 ​ $ — ​ $ 12,977 Over time ​ — ​ 3,692 ​ 3,692 Total ​ $ 12,977 ​ $ 3,692 ​ $ 16,669 Net revenues categorized by customer location are as follows for the years ended December 31: ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues from external customers (in thousands) ​ 2023 ​ 2022 United States $ 5,056 $ 4,379 China ​ 4,745 ​ 5,608 Korea ​ 4,260 ​ 1,360 Germany ​ 1,422 ​ — Taiwan ​ 543 ​ 4,639 Other ​ 2 ​ 25 Singapore ​ — ​ 658 Total ​ $ 16,028 ​ $ 16,669
Schedule of contract assets and liabilities and net revenues recognized in relation to contract liabilities	Details of contract assets and liabilities is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 Contract assets ​ $ 4,313 ​ $ 3,439 Assets recognized for costs incurred to fulfill a contract (*) ​ 13 ​ 12 Contract liabilities ​ 35 ​ 48 (*) The balances are included in prepaid expenses and other current assets in the accompanying condensed consolidated balance sheets.	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ December 31, 2023 ​ December 31, 2022 Contract assets ​ $ 3,439 ​ $ 886 Assets recognized for costs incurred to fulfill a contract (*) ​ 12 ​ 39 Contract liabilities ​ 48 ​ 651 (*)- The balances are included in prepaid expenses and other current assets in the accompanying consolidated balance sheets.
Schedule of net revenues and gross accounts receivable concentration	Net revenues recognized in relation to contract liabilities are as follows as of the periods indicated (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 March 31, 2023 Net revenues recognized that were included in the contract liabilities balance at the beginning of the period ​ $ 12 ​ $ 650 ​	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) December 31, 2023 December 31, 2022 Net revenues recognized that were included in the contract liabilities balance at the beginning of the year ​ $ 651 ​ $ 766 Details of external customers, who contribute more than 10% of the Company’s net revenues and gross accounts receivable as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Revenues ​ Accounts Receivable (in thousands) ​ 2023 ​ 2022 ​ 2023 ​ 2022 Customer A $ * $ 4,639 $ * $ 1,228 Customer B ​ 3,031 ​ 2,979 ​ 1,755 ​ 590 Customer C ​ * ​ 1,712 ​ * ​ 1,400 Customer D ​ * ​ 1,670 ​ 661 ​ 687 Customer E ​ * ​ * ​ * ​ 610 Customer F ​ * ​ * ​ 1,250 ​ * Customer G ​ 3,000 ​ * ​ * ​ * Customer H ​ * ​ * ​ 938 ​ * *Less than 10%
Schedule of changes in provisions for product warranties		Details and changes in provisions for product warranties for the years ended December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Beginning balance ​ $ 64 ​ $ 106 Provision ​ 18 ​ — Adjustment to prior provisions ​ (27) ​ (42) Ending balance ​ $ 55 ​ $ 64
Schedule of foreign currency exchange gains and losses		​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Foreign currency gain, net ​ $ 265 ​ $ 181

Fair Value of Measurements (Tab

Fair Value of Measurements (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value of Measurements
Schedule of classifications of the financial instruments that are measured at fair value on a recurring basis	Fair value hierarchy classifications of the financial instruments that are measured at fair value on a recurring basis are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 10,317 ​ $ 10,317 Warrant liabilities ​ — ​ — ​ 10,584 ​ 10,584 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2023 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2022 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 31,166 ​ $ 31,166
Schedule of valuation techniques and inputs used in the fair value measurement	The table below presents valuation techniques and inputs used in the fair value measurement categorized within Level 3 of the fair value hierarchy (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation techniques Inputs March 31, 2024 December 31, 2023 Convertible promissory notes, current Discounted Cash Flow Model (“DCF”) Discount rate, risk-free rate, credit spread, contractual cash flows ​ $ 5,645 ​ $ — ​ ​ PWERM (“Probability-Weighted Expected Return Method”) ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 27,794 Convertible promissory notes, net of current Binomial Lattice Model (“BLM”) Stock price, volatility, remaining term, risk-free rate, credit spread ​ $ 4,672 ​ $ — ​ ​ PWERM ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 6,239 Warrant liabilities – private and public warrants Black Scholes Merton Model (“BSM”) or BLM Exercise price, term to expiration, volatility, risk-free rate ​ $ 9,150 ​ $ — Warrant liabilities - other ​ ​ ​ ​ $ 1,434 $ —	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Valuation techniques Inputs 2023 2022 Convertible promissory notes, current PWERM Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ 27,794 ​ $ 31,166 Convertible promissory notes, net of current ​ ​ ​ 6,239 ​ —
Schedule of changes in the fair value of the Company's Level 3 financial liabilities	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Convertible promissory notes fair value - beginning of period ​ $ 34,033 ​ $ 31,166 Change in fair value of convertible promissory notes ​ 1,203 ​ (549) Conversion of convertible promissory notes ​ (41,209) ​ — Borrowing of convertible promissory notes ​ 16,290 ​ — Convertible promissory notes fair value - end of period ​ $ 10,317 ​ $ 30,617 ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Warrant Liabilities Fair value - beginning of period ​ $ — ​ $ — Private and public warrants assumed at Closing ​ 5,958 ​ — Change in fair value of warrant liabilities ​ 4,626 ​ — Warrant Liabilities Fair value - end of period ​ $ 10,584 ​ $ —	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Fair value as of beginning of period ​ $ 31,166 ​ $ 56,996 Change in fair value of convertible promissory notes ​ 1,428 ​ 450 Conversion of convertible promissory notes ​ (61) ​ (33,140) Repayment of convertible promissory notes ​ (500) ​ (1,140) Transfer of convertible promissory notes to bank borrowings ​ — ​ (1,000) Borrowing of convertible promissory notes ​ 2,000 ​ 9,000 Fair value as of end of period ​ $ 34,033 ​ $ 31,166

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Balance Sheet Components
Schedule of Inventory	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Raw materials ​ $ 414 ​ $ 448 Work-in-process ​ 498 ​ 601 Finished goods ​ 872 ​ 437 Total inventory ​ $ 1,784 ​ $ 1,486	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Raw materials ​ $ 448 ​ $ 182 Work-in-process ​ 601 ​ 891 Finished goods ​ 437 ​ 2,407 ​ ​ $ 1,486 ​ $ 3,480
Schedule of Prepaid expenses and other assets	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Prepaid expenses ​ $ 3,345 ​ $ 433 Prepaid inventory ​ ​ 1,429 ​ ​ 279 Lease deposit ​ 413 ​ 434 Other receivables and current assets ​ 279 ​ 117 IPO expenses ​ — ​ 1,643 Prepaid expenses and other current assets ​ $ 5,466 ​ $ 2,906	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 IPO expenses ​ $ 1,643 ​ $ — Intellectual property rights ​ 761 ​ 861 Lease deposit ​ 554 ​ 555 Prepaid expenses ​ 433 ​ 799 Prepaid inventory ​ 279 ​ 1,310 Other receivables ​ 105 ​ 102 Costs incurred to fulfill a contract ​ 12 ​ 39 ​ ​ 3,787 ​ 3,666 Less: Non-current assets ​ (881) ​ (993) Prepaid expenses and other current assets ​ $ 2,906 ​ $ 2,673
Schedule of Accrued and other current liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Payroll and related expenses ​ $ 9,830 ​ $ 9,880 Accrued payables ​ ​ 7,853 ​ ​ 6,319 Other taxes payable ​ ​ 3,399 ​ ​ 158 Current portion of interest payable ​ ​ 3,395 ​ ​ 6,915 Professional fees ​ 444 ​ 499 Royalty and license fee ​ 60 ​ 58 Product warranty ​ 64 ​ 55 Other ​ 107 ​ 72 Accrued and other current liabilities ​ $ 25,152 ​ $ 23,956 ​	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Payroll and related expenses ​ $ 10,038 ​ $ 6,635 Accrued payables ​ 6,319 ​ 2,233 Royalty and license fee ​ 58 ​ 37 Professional fees ​ 499 ​ 479 Current portion of interest payable ​ 6,915 ​ 2,944 Product warranty ​ 55 ​ 64 Other ​ 72 ​ 104 ​ ​ $ 23,956 ​ $ 12,496
Schedule of Property and equipment, net		​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Production equipment ​ $ 14,887 ​ $ 14,800 IT equipment ​ 1,127 ​ 1,212 Furniture and fixtures ​ 784 ​ 799 Leasehold improvements ​ 293 ​ 388 Fixed assets in process ​ — ​ 39 Total property and equipment ​ 17,091 ​ 17,238 Less: accumulated depreciation and amortization ​ (16,319) ​ (16,127) ​ ​ $ 772 ​ $ 1,111
Schedule of components of lease expense and other information related to leases		​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Operating lease expense ​ $ 772 ​ $ 733 Finance lease expense ​ ​ Amortization of right of use assets ​ 14 ​ 18 Interest on lease liabilities ​ 1 ​ 2 Total finance lease expense ​ 15 ​ 20 ​ ​ $ 787 ​ $ 753 ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Supplemental cash flow information: ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ Cash used in operations for operating leases ​ $ 766 ​ $ 770 ​ Cash used in operations for finance leases ​ 1 ​ 2 ​ Payments made on finance leases ​ 17 ​ 24 ​ ROU assets obtained in exchange for lease obligations: ​ ​ ​ Operating leases ​ 1,476 ​ 826 ​ Weighted average remaining lease term: ​ ​ ​ Operating leases ​ 2.25 years ​ 3.57 years ​ Finance leases ​ — ​ 0.90 years ​ Weighted average discount rate: ​ ​ ​ Operating leases ​ 4.66 % 4.00 % Finance leases ​ — ​ 9.70 %
Schedule of Maturities of lease liabilities under noncancellable leases		​ ​ ​ ​ ​ ​ Operating (in thousands) ​ leases 2024 ​ $ 743 2025 ​ 712 2026 ​ 169 Total undiscounted lease payments ​ 1,624 Less: imputed interest ​ (94) Total lease liabilities ​ $ 1,530
Schedule of Intangibles, net		​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Intellectual properties ​ $ 1,118 ​ $ 943 Intangible assets in process ​ — ​ 180 Total acquired intangibles ​ 1,118 ​ 1,123 Less: accumulated amortization ​ (873) ​ (451) ​ ​ $ 245 ​ $ 672
Schedule of Other liabilities		​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Severance payments liability ​ $ 92 $ 76 Interest payable ​ 16 — ​ ​ $ 108 $ 76 ​

Debt (Tables)

Debt (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Borrowings
Schedule of borrowings	The Company’s outstanding debt was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 ​ ​ Principal ​ Fair Value ​ Principal ​ Fair Value Convertible promissory notes: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Historical convertible promissory notes ​ $ 5,630 ​ $ 5,645 ​ $ 35,347 ​ $ 34,033 2023 & 2024 convertible promissory notes ​ 5,000 ​ 4,672 ​ — ​ — Borrowings: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ KEB Hana Bank ​ 6,682 ​ 6,682 ​ 6,980 ​ 6,980 IBK Industrial Bank ​ 6,831 ​ 6,831 ​ 7,135 ​ 7,135 Note payable (one individual investor) ​ 1,000 ​ 1,000 ​ 1,000 ​ 1,000 M-Venture Investment, Inc. ​ 7,425 ​ 7,425 ​ 7,756 ​ 7,756 Anapass, Inc, related party ​ 9,653 ​ 9,653 ​ 10,082 ​ 10,082 i Best Investment Co., Ltd ​ 7,425 ​ 7,425 ​ 10,082 ​ 10,082 Kyeongho Lee, related party ​ 824 ​ 824 ​ 1,474 ​ 1,474 Total debt ​ $ 50,470 ​ 50,157 ​ $ 79,856 ​ 78,542 Less: current portion ​ ​ ​ ​ (45,485) ​ ​ ​ ​ (72,303) Debt, net of current portion ​ ​ ​ ​ $ 4,672 ​ ​ ​ ​ $ 6,239 ​	​ ​ ​ ​ ​ ​ ​ ​ ​ Category Creditor Maturity date Annual interest rate Korean Won KEB Hana Bank (*1) 7/12/2024 5.23 % Korean Won IBK Industrial Bank (*1) 11/20/2024 4.89 % Korean Won Anapass, Inc. 7/25/2024 5.50 % Korean Won Anapass, Inc. 5/10/2024 5.50 % Korean Won Anapass, Inc. 9/15/2024 5.50 % Korean Won Kyeongho Lee 11/19/2024 9.00 % Korean Won Kyeongho Lee 5/27/2024 0 % Korean Won Kyeongho Lee 11/24/2023 6.80 % Korean Won Kyeongho Lee 11/30/2024 7.50 % Korean Won Kyeongho Lee 12/2/2024 (*9) 7.50 % Korean Won M-Venture Investment, Inc. (*3) 10/29/2024 6.50 % Korean Won M-Venture Investment, Inc. (*4) 4/26/2024 6.50% - 8.65 %(*6) Korean Won i Best Investment Co., Ltd. (*5) 3/14/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. (*7) 12/22/2023 6.50 % Korean Won i Best Investment Co., Ltd. 3/12/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. 1/12/2024 (*9) 6.50 % Korean Won i Best Investment Co., Ltd. 3/14/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. 1/26/2024 (*2) 6.50 % Promissory Note One (1) individual investor 6/30/2024 4.00 % (*1) The limits for borrowings from KEB Hana Bank and IBK Industrial Bank are $6,980,000 and $7,135,000, respectively, and the bank deposit of Anapass, Inc., a related party, is pledged as collateral for borrowings from KEB Hana Bank and IBK Industrial Bank (see Notes 5 and 12). As of the current fiscal year end, collateral was provided to Anapass, Inc. in relation to the borrowings from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. (see Notes 5 and 12). (*2) Maturity date was extended for five (*3) (*4) (*5) (*6) (*7) (*8) three (*9) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ Category ​ Creditor ​ December 31, 2023 ​ December 31, 2022 Korean Won KEB Hana Bank (*1) ​ $ 6,980 ​ $ 7,102 Korean Won IBK Industrial Bank (*1) ​ 7,135 ​ 7,260 Korean Won Anapass, Inc. ​ 4,653 ​ 4,735 Korean Won Anapass, Inc. ​ 2,327 ​ 2,367 Korean Won Anapass, Inc. ​ 3,102 ​ 3,156 Korean Won Kyeongho Lee ​ 388 ​ 395 Korean Won Kyeongho Lee ​ 85 ​ 87 Korean Won Kyeongho Lee ​ — ​ 24 Korean Won Kyeongho Lee ​ 388 ​ 395 Korean Won Kyeongho Lee ​ 613 ​ 789 Korean Won M-Venture Investment, Inc. (*3) ​ 3,102 ​ 3,156 Korean Won M-Venture Investment, Inc.(*4) ​ 4,653 ​ 4,734 Korean Won i Best Investment Co., Ltd. (*5) ​ 3,102 ​ 3,156 Korean Won i Best Investment Co., Ltd. (*7) ​ — ​ — Korean Won i Best Investment Co., Ltd. ​ 1,551 ​ — Korean Won i Best Investment Co., Ltd. ​ 2,327 ​ — Korean Won i Best Investment Co., Ltd. ​ 2,327 ​ — Korean Won i Best Investment Co., Ltd. ​ 776 ​ — Promissory Note One (1) individual investor ​ 1,000 ​ 1,000 Bank Borrowings ​ $ 44,509 ​ $ 38,356
Schedule of maturities of borrowings	Expected future minimum principal payments under the Company’s total debt is as follows as of March 31, 2024 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible ​ ​ ​ ​ ​ ​ Notes ​ ​ ​ ​ ​ ​ Years ​ Payable ​ Borrowing ​ Total 2024, remainder ​ $ 5,630 ​ $ 39,840 ​ $ 45,470 2025 ​ — ​ — ​ — 2026 ​ 5,000 ​ — ​ 5,000 Total debt ​ $ 10,630 ​ $ 39,840 ​ $ 50,470
Schedule of convertible notes		​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Category ​ Creditor ​ December 31, 2023 ​ December 31, 2022 Current convertible notes (*1) ​ ​ 1st SG Ace Inc. (*2) ​ $ 7,620 ​ $ 8,461 2nd M-Venture Investment, Inc. and one (1) institution (*3) ​ 7,620 ​ 8,461 7th NA Korea Trans Fund No.4, one (1) institution and eight(8) individual investors (*4) ​ 2,198 ​ 1,932 16th NA Korea Trans Fund No.4 and two (2) individual investors ​ 387 ​ 330 22nd i Best Investment Co., Ltd. ​ 3,233 ​ 2,746 23rd Jeju Semiconductor Corp. ​ 908 ​ 771 24th One (1) individual investor ​ 665 ​ 565 25th M-Venture Investment Inc. (*5) ​ — ​ 3,511 26th Access Bio, Inc. ​ 5,163 ​ 4,389 ​ Subtotal ​ 27,794 ​ 31,166 Non-current convertible notes ​ ​ 25th M-Venture Investment Inc. (*5) ​ 3,614 ​ — 27th Blacktree Co., Ltd. ​ 2,625 ​ — ​ Subtotal ​ 6,239 ​ — ​ Total ​ $ 34,033 ​ $ 31,166 (*1) (*2) (*3) (*4) (*5)
Schedule of terms of issuance of convertible notes		Key terms for issuance of convertible notes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1st 2nd 7th 16th 22nd 23rd 24th 25th 26th 27th Issue Year ​ 2017 2017 2019 2020 2021 2021 2021 2022 2022 ​ 2023 Early repayment ​ (*1) (*1) (*2) (*1) (*1) (*1) (*1) (*2) (*3) ​ (*1) Repayment at maturity ​ The payment shall be made three years after the date of issue at an annual interest rate of 4% . The payment shall be made three years after the date of issue at an annual interest rate of 7% . The payment shall be made three years after the date of issue at an annual interest rate of 5% . The payment shall be made three years after the date of issue at an annual interest rate of 4% . ​ The payment shall be made three years after the date of issue at an annual interest rate of 5% . Rates applied at the repayment date ​ Upon repayment, there is a clause to reimburse the U.S. Dollar amount converted at the Won-Dollar exchange rate on the redemption date based on the Won amount converted at the Won-Dollar exchange rate at the date of issue. ​ N/A N/A N/A N/A N/A N/A ​ N/A Conversion price ​ $ 3.50 per share (*4) ​ ​ $ 6.67 per share ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1st 2nd 7th 16th 22nd 23rd 24th 25th 26th 27th Conversion - The holder of convertible notes can covert it at any time. ​ - If the Company issues a new equity instrument after issuing convertible notes, the holder of convertible notes may participate in conversion with the issuance price of the new equity instruments (1st, 2nd and 27th convertible notes) or $3.50 per share up to seven days prior to the issuance of the equity instruments. ​ - Conversion upon demand at holder’s discretion with conversion price equal to $3.50 ($6.67 for 27th convertible note) per share after issue date. ​ - Automatic conversion in an initial public offering (“IPO”) or business combination with SPAC (except for 1st and 24th convertible notes) (conversion price is adjusted to IPO price or SPAC conversion price). ​ - If the price at the time of issuance of a new equity instrument or the IPO is lower than $3.50, the conversion price of the convertible note is adjusted (except for 27th convertible note). ​ - Conversion price is adjusted every three months for one year after an IPO at KOSDAQ (However, adjusted price cannot be lower than 70% of $3.50 per share and cannot be higher than $3.50 per share) (7th convertible note). Number of convertible shares (*5) 5,142,858 shares ​ 553,790 shares 102,597 shares 874,286 shares 245,714 shares 180,000 shares 1,000,000 shares 1,428,571 shares 299,850 shares Collateral and guarantee (*6) ​ (*7) N/A (*8) N/A (*7) N/A (*7) N/A (*1) early repayment exercised once every quarter times in total for periods after from date issue convertible notes until from the date issue convertible notes (*2) times periods convertible convertible (*3) (*4) (*5) (*6) shares (*7) (*8)
Notes and loans payable
Borrowings
Schedule of maturities of borrowings		Maturities of borrowings as of December 31, 2023 were as follows: ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2024 ​ $ 44,509 Total ​ $ 44,509
Convertible debt
Borrowings
Schedule of maturities of borrowings		Maturities of convertible notes as of December 31, 2023, were as follows: ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2024 ​ $ 27,794 December 31, 2025 ​ 3,614 December 31, 2026 ​ 2,625 Total ​ $ 34,033

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies.
Schedule of collateral provided to Anapass, Inc	The following table includes a summary of the collateral provided to Anapass, Inc. (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, Secured ​ ​ 2024 ​ 2023 ​ Creditor Cash and cash equivalents ​ $ 16,122 ​ $ 254 ​ ​ Accounts receivable ​ ​ 5,118 ​ ​ 4,920 ​ Inventory ​ 1,784 ​ 1,486 Anapass, Inc. Property and equipment ​ 1,988 ​ 352 Intangible assets and others ​ 187 ​ 199 ​	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) December 31, December 31, Secured ​ ​ 2023 ​ 2022 ​ Creditor Cash and cash equivalents ​ $ 254 ​ $ 1,363 Accounts receivable ​ 4,920 ​ 4,453 Inventory ​ 1,486 ​ 3,480 Anapass, Inc. Property and equipment ​ 352 ​ 485 Intangible assets and others ​ 199 ​ 531 ​

Common Stock (Tables)

Common Stock (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Common Stock
Summary of shares reserved for shares authorized but unissued common stock	The Company has reserved shares of common stock for issuance as follows (in thousands): ​ ​ ​ ​ ​ ​ March 31 December 31 ​ ​ 2024 ​ 2023 Warrants ​ 26,724 ​ 2,894 Shares available for future grant from 2024 plan ​ 3,983 ​ — Convertible promissory notes 800 1,835 Options issued and outstanding 668 668 Shares available for future grant from 2024 ESPP 600 — RSUs outstanding 392 392 Shares available for future grant from 2011 plan — 113 Total 33,167 5,902 ​	The Company has reserved the following shares of authorized but unissued common stock as of December 31, 2023 ​ ​ ​ Options outstanding 3,579,294 RSUs outstanding 2,099,970 Shares available for grant from 2011 plan 605,826 Warrants 9,200,000 Convertible promissory notes 9,827,666 Total 25,312,756 ​

Warrants (Tables)

Warrants (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Warrants
Summary of warrants	The following table represents a summary of warrants to purchase shares of the Company’s common stock that are outstanding (in thousands, except for exercise price): ​ ​ ​ ​ ​ ​ ​ Issue Date March 31, 2024 Exercise Price Expiration August 2021 ​ 299 ​ $ 10.00 - $18.75 ​ (1) September 2021 300 ​ $ 5.00 (1) February 2023 - June 2023 2,115 ​ $ 10.00 - $18.75 (1) July 2023 80 ​ $ 10.00 (1) October 2023 100 ​ $ 10.00 (1) Private and public warrants 23,830 ​ $ 11.50 ​ March 26, 2029 Tota l 26,724 ​ ​ (1) Within 3 years from the date of issuance.	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Issued Exercised Expired/ Outstanding ​ ​ ​ ​ ​ ​ Cancelled ​ ​ December 2020 (*1) 2,514,285 — (2,514,285) — February 2021 (*2) 342,857 — (342,857) — August 2021 (*3) 999,997 — — 999,997 September 2021 (*3) 428,571 — — 428,571 February 2023 ~ June 2023 (*7) (*9) 7,685,717 (428,572) — 7,257,145 July 2023 (*7) 228,572 — — 228,572 October 2023 (*7) 285,715 — — 285,715 ​ ​ ​ ​ ​ ​ ​ ​ ​ Exercise Price Expiration December 2020 (*1) ​ $ 3.50 (*5) Earlier of within 2 years from the date of issuance or 2 weeks before U.S. IPO or Korea IPO February 2021 (*2) ​ $ 3.50 (*4) Within 18 months from the date of issuance August 2021 (*3) ​ $ 3.50 (*6) Within 3 years from the date of issuance September 2021 (*3) ​ $ 3.50 (*5) Within 3 years from the date of issuance February 2023 ~ June 2023 (*7) (*9) ​ $ 3.50 (*8) Within 3 years from the date of issuance July 2023 (*7) ​ $ 3.50 (*10) Within 3 years from the date of issuance October 2023 (*7) ​ $ 3.50 (*10) Within 3 years from the date of issuance (*1) (*2) (*3) (*4) (*5) (*6) (*7) (*8) (*9) (*10)

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Stock-Based Compensation
Summary of stock option activity	Stock options outstanding under the 2024 Plan were as follows (in thousands, except per share amounts and years): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Number of ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ Options ​ Average ​ Contractual Life ​ Aggregated ​ ​ Outstanding ​ Exercise Price ​ (in Years) ​ Intrinsic Value Balance as of December 31, 2023 ​ 3,579 ​ $ 0.02 ​ 5.5 ​ $ 4,405 Reverse recapitalization ​ (2,911) ​ ​ 0.09 ​ — ​ ​ — Balance as of December 31, 2023 (1) ​ 668 ​ ​ 0.11 ​ 5.5 ​ ​ 4,405 Granted ​ — ​ ​ — ​ — ​ ​ — Exercised ​ — ​ ​ — ​ — ​ ​ — Cancelled ​ — ​ ​ — ​ — ​ ​ — Balance as of March 31, 2024 668 $ 0.11 5.3 $ 5,543 Vested as of March 31, 2024 667 ​ $ 0.11 5.3 $ 5,532 Exercisable as of March 31, 2024 634 ​ $ 0.11 5.1 $ 5,256 (1) Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (see Note 3).	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Number of ​ ​ ​ ​ Average ​ ​ Shares ​ Stock ​ Weighted- ​ Remaining ​ ​ Available ​ Options ​ Average ​ Contractual Life ​ for Grant Outstanding Exercise Price (Years) Balances as of January 1, 2022 ​ 1,679,763 ​ ​ 8,194,822 ​ $ 0.02 ​ 6.1 Granted (105,000) ​ 105,000 ​ 0.02 Exercised — ​ (2,459,014) ​ 0.02 Cancelled 1,066,916 ​ (1,066,916) ​ 0.02 Balances as of December 31, 2022 2,641,679 ​ 4,773,892 ​ 0.02 5.1 RSUs granted (2,099,970) ​ — ​ — Exercised — ​ (1,130,481) ​ 0.02 Cancelled 64,117 ​ (64,117) ​ 0.02 Balances as of December 31, 2023 605,826 ​ 3,579,294 ​ 0.02 5.5 Vested as of December 31, 2023 ​ ​ ​ 3,311,859 ​ $ 0.02 ​ 5.3 Vested and expected to be vest as of December 31, 2023 ​ ​ ​ 3,569,024 ​ $ 0.02 ​ 5.5
Summary of assumptions used to calculate fair value of employee stock options		​ ​ ​ ​ ​ ​ 2022 Estimated term (in years) 5.8 ​ Risk-free interest rate 1.85 % Expected volatility 65 % Expected dividend yield 0 %
Summary of RSUs activity	RSUs outstanding under the 2024 Plan were as follows (in thousands, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of RSUs ​ Average Grant ​ ​ Outstanding ​ Date Fair Value Balance as of December 31, 2023 ​ 2,100 ​ $ 1.15 Reverse recapitalization ​ (1,708) ​ ​ 5.01 Balances as of December 31, 2023 (1) ​ 392 ​ $ 6.16 Granted — ​ — Vested — ​ — Cancelled — ​ — Balance as of March 31, 2024 392 ​ $ 6.16 (1) Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (see Note 3).	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of ​ Average Grant ​ Shares Date Fair Value Nonvested, outstanding at December 31, 2022 — ​ $ — Granted 2,099,970 ​ 1.15 Vested — ​ — Cancelled — ​ — Nonvested, outstanding at December 31, 2023 2,099,970 ​ $ 1.15

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Employee Benefit Plans
Summary of net liability for severance payments	The net liability for severance payments as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 Liability for severance payments, beginning ​ $ 7,764 ​ $ 7,997 Deposit ​ (276) ​ (308) Liability for severance payments, ending ​ $ 7,488 ​ $ 7,689 ​	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Liability for severance payments ​ $ 7,997 ​ $ 7,248 Deposit ​ (308) ​ (343) ​ ​ $ 7,689 ​ $ 6,905 ​

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Related Party Transactions
Summary of balances and transactions with the related parties	A summary of balances and transactions with the related parties who are stockholders of the Company were as follows as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 ​ ​ Anapass Kyeongho Lee ​ Anapass Kyeongho Lee Borrowings ​ $ 9,653 ​ $ 824 ​ $ 10,082 ​ $ 1,474 Other current liabilities ​ 106 ​ 87 ​ 212 ​ 182	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ 2023 ​ 2022 ​ Anapass Kyeongho Lee Anapass Kyeongho Lee Borrowings ​ $ 10,082 ​ $ 1,474 ​ $ 10,257 ​ $ 1,690 Other current liabilities ​ 212 ​ 182 ​ 11 ​ 150 Interest expense ​ 548 ​ 110 ​ 389 ​ 140 ​

Segments and Information (Table

Segments and Information (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Segments and Information
Summary of long-lived assets by geographic region	The Company operates in one segment. Revenue information by geographic region is presented in Note 4 to these condensed consolidated financial statements. Long-lived assets by geographic region were as follows as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 South Korea ​ $ 1,170 ​ $ 1,363 United States ​ 817 ​ 930 Total long-lived assets ​ $ 1,987 ​ $ 2,293 ​	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 United States ​ $ 930 ​ $ 1,295 South Korea ​ 1,363 ​ 626 Total long-lived assets ​ $ 2,293 ​ $ 1,921 ​

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Net Income (Loss) Per Share
Summary of computation of basic and diluted net loss per share	The following table summarizes the computation of basic and diluted net income (loss) per share (in thousands, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Numerator: ​ ​ Net income (loss), basic and diluted ​ $ 757 ​ $ (1,393) Denominator: ​ ​ Weighted-average common shares outstanding, basic ​ 25,468 ​ 23,862 Add: effect of dilutive securities ​ 789 ​ — Weighted-average common shares outstanding, diluted ​ 26,257 ​ 23,862 Net income (loss) per share, basic and diluted ​ ​ Basic ​ $ 0.03 ​ $ (0.06) Diluted ​ $ 0.03 ​ $ (0.06)
Schedule of Potentially dilutive securities that were excluded from the computation of diluted net loss per common share	The following outstanding potentially dilutive common stock equivalents were excluded from the computation of diluted net income (loss) per share for the periods indicated because including them would have been antidilutive (in thousands): ​ ​ ​ ​ ​ ​ March 31, ​ ​ 2024 2023 Warrants 26,724 995 Convertible promissory notes 5,543 1,809 Options — 885 Total 32,267 3,689 ​	​ ​ ​ ​ ​ ​ ​ 2023 2022 Convertible promissory notes 9,827,666 9,688,740 Warrants 9,200,000 3,942,853 Options 3,579,294 4,773,892 Restricted Stock Units (RSU) 2,099,970 — Total 24,706,930 18,405,485

Organization and Liquidity (Det

Organization and Liquidity (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 26, 2024	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Organization and Liquidity
Exchange ratio		0.1868
Accumulated deficit	$ (548,897)		$ (549,654)	$ (527,185)
Cash and cash equivalents	16,122		$ 258	$ 1,398
Cash proceeds from the reverse recapitalization and PIPE Financing	$ 17,238

Summary of Significant Accoun_3

Summary of Significant Accounting Policies and Basis of Presentation - Provision for Credit Losses (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Organization and Liquidity
Provisions for credit losses	$ 1,900,000	$ 1,644,000	$ 549,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies and Basis of Presentation - Concentration of Revenues and Accounts Receivable (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024 customer	Dec. 31, 2023 USD ($) customer	Dec. 31, 2022 USD ($) customer
Customer A
The Company and Summary of Significant Accounting Policies
Accounts Receivable			$ 1,228
Customer B
The Company and Summary of Significant Accounting Policies
Accounts Receivable		$ 1,755	590
Customer C
The Company and Summary of Significant Accounting Policies
Accounts Receivable			1,400
Customer D
The Company and Summary of Significant Accounting Policies
Accounts Receivable		661	687
Customer E
The Company and Summary of Significant Accounting Policies
Accounts Receivable			$ 610
Customer F
The Company and Summary of Significant Accounting Policies
Accounts Receivable		1,250
Customer H
The Company and Summary of Significant Accounting Policies
Accounts Receivable		$ 938
Revenue
The Company and Summary of Significant Accounting Policies
Number of customers | customer		2	4
Revenue | Two customers
The Company and Summary of Significant Accounting Policies
Number of customers | customer	2
Revenue | Four customers
The Company and Summary of Significant Accounting Policies
Number of customers | customer		4
Revenue | Customer concentration | Two customers
The Company and Summary of Significant Accounting Policies
Concentration risk percentage		38%
Revenue | Customer concentration | Four customers
The Company and Summary of Significant Accounting Policies
Concentration risk percentage			66%
Revenue | Customer concentration | Customer A
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	61%	28%
Revenue | Customer concentration | Customer B
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	24%	28%
Revenue | Customer concentration | Customer C
The Company and Summary of Significant Accounting Policies
Concentration risk percentage		25%
Revenue | Customer concentration | Customer D
The Company and Summary of Significant Accounting Policies
Concentration risk percentage		10%
Accounts receivable
The Company and Summary of Significant Accounting Policies
Number of customers | customer		4	5
Accounts receivable | Four customers
The Company and Summary of Significant Accounting Policies
Number of customers | customer	4	4
Accounts receivable | Customer concentration | Four customers
The Company and Summary of Significant Accounting Policies
Concentration risk percentage		70%
Accounts receivable | Customer concentration | Five customers
The Company and Summary of Significant Accounting Policies
Concentration risk percentage			90%
Accounts receivable | Customer concentration | Customer A
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	28%	27%
Accounts receivable | Customer concentration | Customer B
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	19%	19%
Accounts receivable | Customer concentration | Customer C
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	18%	14%
Accounts receivable | Customer concentration | Customer D
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	13%	10%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies and Basis of Presentation - Foreign Currency (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Organization and Liquidity
Foreign currency transactions	$ 1,100	$ 700	$ 265	$ 181

Reverse Recapitalization - Busi

Reverse Recapitalization - Business Combination (Details) $ / shares in Units, $ in Millions	Mar. 26, 2024 USD ($) $ / shares	Dec. 31, 2023 $ / shares
Reverse Recapitalization [Line Items]
Conversion price | $ / shares		$ 3.50
Concord III
Reverse Recapitalization [Line Items]
Transaction costs incurred in acquisition | $	$ 13.1
Conversion price | $ / shares		$ 1
Concord III | PIPE financing
Reverse Recapitalization [Line Items]
Transaction costs incurred in acquisition | $	0.9
Legacy G C T
Reverse Recapitalization [Line Items]
Transaction costs incurred in acquisition | $	$ 8.9
Legacy G C T | Concord III
Reverse Recapitalization [Line Items]
Percentage of ownership acquired	100%
Net proceeds received on acquisition | $	$ 17.1
Share price in business acquisition | $ / shares	$ 10
Stock exchange ratio	0.1868
Legacy G C T | Concord III | Convertible debt
Reverse Recapitalization [Line Items]
Conversion price | $ / shares	$ 6.67

Reverse Recapitalization - Numb

Reverse Recapitalization - Number of shares of common stock issued and outstanding post Business Combination (Details) - shares		12 Months Ended
	Mar. 26, 2024	Dec. 31, 2023	Mar. 31, 2024	Dec. 31, 2022
Reverse Recapitalization
Common stock, shares outstanding		24,166,000	45,833,000	24,166,000
Total common stock issued and outstanding	45,833,000	24,166,000	45,833,000	127,760,265
Sponsor Earnout Shares
Reverse Recapitalization
Sponsor earnout common stock outstanding prior to the Business Combination	8,625,000
PIPE financing
Reverse Recapitalization
Common stock issued in PIPE Financing	4,530,000
Concord III
Reverse Recapitalization
Common stock, shares outstanding	3,941,000
Less: redemption of Concord I I I's common stock	(3,766,000)	(30,558,639)
Common stock of Concord I I I issued and outstanding	8,800,000
Legacy G C T
Reverse Recapitalization
Legacy GCT common stock	32,503,000

Reverse Recapitalization - Reve

Reverse Recapitalization - Reverse Recapitalization (Details)	Mar. 26, 2024 USD ($)
Concord III | Legacy G C T
Reverse Recapitalization [Line Items]
Goodwill and intangible assets	$ 0

Reverse Recapitalization - PIPE

Reverse Recapitalization - PIPE Financing (Details) - PIPE financing $ / shares in Units, $ in Millions	Mar. 26, 2024 USD ($) $ / shares shares
Reverse Recapitalization [Line Items]
Number of shares issued | shares	4,529,967
Issue price per share | $ / shares	$ 6.67
Value of shares issued	$ 30.2
Net proceeds from PIPE financing	$ 17.1

Reverse Recapitalization -Priva

Reverse Recapitalization -Private Warrants and Public warrants (Details) - shares	1 Months Ended	3 Months Ended
	Nov. 30, 2021	Mar. 31, 2024
Reverse Recapitalization [Line Items]
Number of warrants issued		26,724,000
Concord III | Private placement warrants
Reverse Recapitalization [Line Items]
Number of warrants issued	9,400,000
Concord III | Public warrants
Reverse Recapitalization [Line Items]
Number of warrants issued	17,250,000
Legacy G C T | Private placement and public warrants | Sponsor
Reverse Recapitalization [Line Items]
Number of warrants vested and retained	4,492,650
Number of warrants reallocated to others	2,087,350
Number of warrants forfeited	2,820,000

Reverse Recapitalization - Lega

Reverse Recapitalization - Legacy GCT and Sponsor Earn out Shares (Details) - Legacy G C T $ / shares in Units, $ in Millions	Mar. 26, 2024 USD ($) $ / shares shares
Earnout shares
Reverse Recapitalization [Line Items]
Number of shares issued	20,000,000
Threshold trading days calculated for issuing shares	60 days
Fair value of shares issued | $	$ 108.8
Impact on stockholder's equity | $	$ 0
Earnout shares | VWAP of the Company's common stock equals or exceeds $12.50 per share
Reverse Recapitalization [Line Items]
Number of shares issued	6,666,667
Threshold trading days calculated for issuing shares	20 days
Consecutive threshold trading days calculated for issuing shares	30 days
Threshold VWAP of stock to trigger earn out shares | $ / shares	$ 12.50
Earnout shares | VWAP of the Company's common stock equals or exceeds $15.00 per share
Reverse Recapitalization [Line Items]
Number of shares issued	6,666,666
Threshold trading days calculated for issuing shares	20 days
Consecutive threshold trading days calculated for issuing shares	30 days
Threshold VWAP of stock to trigger earn out shares | $ / shares	$ 15
Earnout shares | VWAP of the Company's common stock equals or exceeds $17.50 per share
Reverse Recapitalization [Line Items]
Number of shares issued	6,666,667
Threshold trading days calculated for issuing shares	20 days
Consecutive threshold trading days calculated for issuing shares	30 days
Threshold VWAP of stock to trigger earn out shares | $ / shares	$ 17.50
Sponsor Earnout Shares
Reverse Recapitalization [Line Items]
Number of shares issued	1,920,375
Threshold trading days calculated for issuing shares	6 months
Fair value of shares issued | $	$ 10.4
Impact on stockholder's equity | $	$ 0
Sponsor Earnout Shares | Minimum
Reverse Recapitalization [Line Items]
Number of shares issued	570,796
Sponsor Earnout Shares | VWAP of the Company's common stock equals or exceeds $12.50 per share
Reverse Recapitalization [Line Items]
Number of shares issued	640,125
Threshold trading days calculated for issuing shares	20 days
Consecutive threshold trading days calculated for issuing shares	30 days
Threshold VWAP of stock to trigger earn out shares | $ / shares	$ 12.50
Sponsor Earnout Shares | VWAP of the Company's common stock equals or exceeds $15.00 per share
Reverse Recapitalization [Line Items]
Number of shares issued	640,125
Threshold trading days calculated for issuing shares	20 days
Consecutive threshold trading days calculated for issuing shares	30 days
Threshold VWAP of stock to trigger earn out shares | $ / shares	$ 15
Sponsor Earnout Shares | VWAP of the Company's common stock equals or exceeds $17.50 per share
Reverse Recapitalization [Line Items]
Number of shares issued	640,125
Threshold trading days calculated for issuing shares	20 days
Consecutive threshold trading days calculated for issuing shares	30 days
Threshold VWAP of stock to trigger earn out shares | $ / shares	$ 17.50

Disaggregation of Revenue - Rev

Disaggregation of Revenue - Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue
Revenues from contracts with customers	$ 3,265	$ 3,062	$ 16,028	$ 16,669
At a point in time
Disaggregation of Revenue
Revenues from contracts with customers	2,378	599	10,968	12,977
Over time
Disaggregation of Revenue
Revenues from contracts with customers	887	2,463	5,060	3,692
Product Revenues
Disaggregation of Revenue
Revenues from contracts with customers	2,378	599	10,968	12,977
Product Revenues | At a point in time
Disaggregation of Revenue
Revenues from contracts with customers	2,378	599	10,968	12,977
Service Revenues
Disaggregation of Revenue
Revenues from contracts with customers	887	2,463	5,060	3,692
Service Revenues | Over time
Disaggregation of Revenue
Revenues from contracts with customers	$ 887	$ 2,463	$ 5,060	$ 3,692

Disaggregation of Revenue - Net

Disaggregation of Revenue - Net revenues categorized by customer location (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue
Revenues from contracts with customers	$ 3,265	$ 3,062	$ 16,028	$ 16,669
Korea
Disaggregation of Revenue
Revenues from contracts with customers	2,000		4,260	1,360
Germany
Disaggregation of Revenue
Revenues from contracts with customers	796		1,422
United States
Disaggregation of Revenue
Revenues from contracts with customers	389	1,968	5,056	4,379
China
Disaggregation of Revenue
Revenues from contracts with customers	$ 80	$ 1,094	4,745	5,608
TAIWAN
Disaggregation of Revenue
Revenues from contracts with customers			543	4,639
Other
Disaggregation of Revenue
Revenues from contracts with customers			$ 2	25
SINGAPORE
Disaggregation of Revenue
Revenues from contracts with customers				$ 658

Disaggregation of Revenue - Con

Disaggregation of Revenue - Contract assets and liabilities (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue
Contract assets	$ 4,313,000	$ 3,439,000	$ 3,439,000	$ 886,000	$ 661,000
Assets recognized for costs incurred to fulfill a contract (*)	13,000	12,000	12,000	39,000
Contract liabilities	35,000	48,000	48,000	651,000
Contract asset recognized			2,560,000	879,000
Revenues recognized that were included in the contract liabilities	$ 12,000	$ 650,000	651,000	766,000
Development services
Disaggregation of Revenue
Contract asset recognized			0	650,000
Technical advice and maintenance services
Disaggregation of Revenue
Contract asset recognized			$ 48,000	$ 0

Fair Value of Measurements (Det

Fair Value of Measurements (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Fair Value of Measurements
Convertible promissory notes	$ 10,317	$ 34,033	$ 31,166
Warrant liabilities	10,584
Level 3
Fair Value of Measurements
Convertible promissory notes	10,317	$ 34,033	$ 31,166
Warrant liabilities	$ 10,584

Fair Value of Measurements - Va

Fair Value of Measurements - Valuation techniques and the inputs (Details) $ in Thousands	Mar. 31, 2024 USD ($) $ / shares Y	Dec. 31, 2023 USD ($)
Binomial Lattice Model ("BLM") | Exercise price | Public warrants
Fair Value of Measurements
Warrant liabilities, measurement input | $ / shares	11.50
Binomial Lattice Model ("BLM") | Term to expiration | Public warrants
Fair Value of Measurements
Warrant liabilities, measurement input | Y	5
Black Scholes Merton Model ("BSM") or BLM | Exercise price | Private placement warrants
Fair Value of Measurements
Warrant liabilities, measurement input | $ / shares	11.50
Black Scholes Merton Model ("BSM") or BLM | Term to expiration | Private placement warrants
Fair Value of Measurements
Warrant liabilities, measurement input | Y	5
Black Scholes Merton Model ("BSM") or BLM | Volatility | Private placement warrants
Fair Value of Measurements
Warrant liabilities, measurement input	0.194
Black Scholes Merton Model ("BSM") or BLM | Risk-free rate | Private placement warrants
Fair Value of Measurements
Warrant liabilities, measurement input	0.042
Convertible promissory notes, current | Discounted Cash Flow Model ("DCF") | Level 3
Fair Value of Measurements
Fair value | $	$ 5,645
Convertible promissory notes, current | Discounted Cash Flow Model ("DCF") | Discount factor
Fair Value of Measurements
Convertible promissory notes, measurement input	0.102
Convertible promissory notes, current | Discounted Cash Flow Model ("DCF") | Remaining term
Fair Value of Measurements
Convertible promissory notes, measurement input | Y	0.25
Convertible promissory notes, current | PWERM | Level 3
Fair Value of Measurements
Fair value | $		$ 27,794
Convertible promissory notes, net of current | PWERM | Level 3
Fair Value of Measurements
Fair value | $		$ 6,239
Convertible promissory notes, net of current | Binomial Lattice Model ("BLM") | Level 3
Fair Value of Measurements
Fair value | $	$ 4,672
Convertible promissory notes, net of current | Binomial Lattice Model ("BLM") | Stock price
Fair Value of Measurements
Convertible promissory notes, measurement input | $ / shares	6.58
Convertible promissory notes, net of current | Binomial Lattice Model ("BLM") | Remaining term
Fair Value of Measurements
Convertible promissory notes, measurement input | Y	1.9
Convertible promissory notes, net of current | Binomial Lattice Model ("BLM") | Credit spread
Fair Value of Measurements
Convertible promissory notes, measurement input	0.050
Convertible promissory notes, net of current | Binomial Lattice Model ("BLM") | Volatility
Fair Value of Measurements
Convertible promissory notes, measurement input	0.322
Convertible promissory notes, net of current | Binomial Lattice Model ("BLM") | Risk-free rate
Fair Value of Measurements
Convertible promissory notes, measurement input	0.046
Warrant liabilities - private and public warrants | Black Scholes Merton Model ("BSM") or BLM | Level 3
Fair Value of Measurements
Fair value | $	$ 9,150
Warrant liabilities - other | Level 3
Fair Value of Measurements
Fair value | $	$ 1,434
Warrant liabilities - other | Black Scholes Merton Model ("BSM") or BLM | Exercise price | Minimum
Fair Value of Measurements
Warrant liabilities, measurement input | $ / shares	5
Warrant liabilities - other | Black Scholes Merton Model ("BSM") or BLM | Exercise price | Weighted average
Fair Value of Measurements
Warrant liabilities, measurement input | $ / shares	10
Warrant liabilities - other | Black Scholes Merton Model ("BSM") or BLM | Exercise price | Maximum
Fair Value of Measurements
Warrant liabilities, measurement input | $ / shares	18.75
Warrant liabilities - other | Black Scholes Merton Model ("BSM") or BLM | Term to expiration | Minimum
Fair Value of Measurements
Warrant liabilities, measurement input | Y	0.4
Warrant liabilities - other | Black Scholes Merton Model ("BSM") or BLM | Term to expiration | Maximum
Fair Value of Measurements
Warrant liabilities, measurement input | Y	2.6
Warrant liabilities - other | Black Scholes Merton Model ("BSM") or BLM | Volatility | Minimum
Fair Value of Measurements
Warrant liabilities, measurement input	0.295
Warrant liabilities - other | Black Scholes Merton Model ("BSM") or BLM | Volatility | Maximum
Fair Value of Measurements
Warrant liabilities, measurement input	0.327
Warrant liabilities - other | Black Scholes Merton Model ("BSM") or BLM | Risk-free rate | Minimum
Fair Value of Measurements
Warrant liabilities, measurement input	0.044
Warrant liabilities - other | Black Scholes Merton Model ("BSM") or BLM | Risk-free rate | Maximum
Fair Value of Measurements
Warrant liabilities, measurement input	0.054

Fair Value of Measurements - Ch

Fair Value of Measurements - Changes in the fair value (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended		24 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023
Fair Value of Measurements
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other (expenses) income, net	Other (expenses) income, net			Interest expense
Convertible promissory notes
Fair Value of Measurements
Fair value as of beginning of period	$ 34,033	$ 31,166	$ 31,166	$ 56,996	$ 56,996
Change in fair value	1,203	(549)	1,428	450
Conversion	(41,209)
Conversion of convertible promissory notes			(61)	(33,140)
Repayment of convertible promissory notes			(500)	(1,140)
Transfer of convertible promissory notes to bank borrowings				(1,000)
Borrowing	16,290		2,000	9,000
Fair value as of end of period	10,317	$ 30,617	$ 34,033	$ 31,166	$ 34,033
Warrant liabilities
Fair Value of Measurements
Assumed at closing	5,958
Change in fair value	4,626
Fair value as of end of period	$ 10,584

Balance Sheet Components - Inve

Balance Sheet Components - Inventory (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Inventory
Raw materials	$ 414,000		$ 448,000	$ 182,000
Work-in-process	498,000		601,000	891,000
Finished goods	872,000		437,000	2,407,000
Total inventory	1,784,000		1,486,000	3,480,000
Write-downs of inventory	$ 0	$ 0	$ 358,000	$ 338,000

Balance Sheet Components - Prep

Balance Sheet Components - Prepaid expenses and other assets (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Components
Prepaid expenses	$ 3,345	$ 433
Prepaid inventory	1,429	279
Lease deposit	413	554	$ 555
Other receivables and current assets	279	117
IPO expenses		(1,643)
Prepaid expenses and other current assets	$ 5,466	$ 2,906	$ 2,673

Balance Sheet Components - Accr

Balance Sheet Components - Accrued and other current liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Components
Payroll and related expenses	$ 9,830	$ 10,038	$ 6,635
Accrued payables	7,853	6,319	2,233
Other taxes payable	3,399	158
Current portion of interest payable	3,395	6,915	2,944
Professional fees	444	499	479
Royalty and license fee	60	58	37
Product warranty	64	55	64
Other	107	72	104
Accrued and other current liabilities	$ 25,152	$ 23,956	$ 12,496

Debt - Outstanding debt (Detail

Debt - Outstanding debt (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Borrowings
Borrowings	$ 50,470	$ 79,856
Fair Value	50,157	78,542
Less: current portion	(45,485)	(72,303)
Debt, net of current portion	4,672	6,239
Historical convertible promissory notes
Borrowings
Borrowings	5,630	35,347
Fair Value	5,645	34,033
2023 & 2024 convertible promissory notes
Borrowings
Borrowings	5,000
Fair Value	4,672
Borrowings
Borrowings
Borrowings	39,840
Borrowings | KEB Hana Bank
Borrowings
Borrowings	6,682	6,980
Fair Value	6,682	6,980
Borrowings | IBK Industrial Bank
Borrowings
Borrowings	6,831	7,135
Fair Value	6,831	7,135
Borrowings | Note payable (one individual investor)
Borrowings
Borrowings	1,000	1,000
Fair Value	1,000	1,000
Borrowings | M-Venture Investment, Inc.
Borrowings
Borrowings	7,425	7,756
Fair Value	7,425	7,756
Borrowings | Anapass, Inc, related party
Borrowings
Borrowings	9,653	10,082
Fair Value	9,653	10,082
Borrowings | i Best Investment Co., Ltd
Borrowings
Borrowings	7,425	10,082
Fair Value	7,425	10,082
Borrowings | Kyeongho Lee
Borrowings
Borrowings	824	1,474
Fair Value	$ 824	$ 1,474

Debt - Expected future minimum

Debt - Expected future minimum principal payments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Borrowings
2024, remainder	$ 45,470
2025	0
2026	5,000
Total	50,470	$ 79,856
Convertible Notes
Borrowings
2024, remainder	5,630
2025	0
2026	5,000
Total	10,630
Borrowings
Borrowings
2024, remainder	39,840
2025	0
Total	$ 39,840

Debt - Convertible Promissory N

Debt - Convertible Promissory Notes (Details) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($) item $ / shares shares	Dec. 31, 2022 USD ($) shares	Feb. 29, 2024 USD ($)	Dec. 31, 2023 USD ($) $ / shares
Borrowings
Amount of debt converted		$ 32,500
Number of shares issued on conversion of debt | shares		10,026,354
Conversion price | $ / shares				$ 3.50
Amount outstanding	$ 50,470			$ 79,856
Minimum
Borrowings
Conversion price | $ / shares				$ 3.50
Historical convertible promissory notes
Borrowings
Amount of debt converted	$ 32,100
Number of shares issued on conversion of debt | shares	4,258,223
Amount of principal and interest outstanding	$ 7,900
Number of noteholders | item	2
Conversion price | $ / shares	$ 3.50
Amount outstanding	$ 5,630			$ 35,347
Historical convertible promissory notes | Minimum
Borrowings
Interest rate (as a percent)	4%
Historical convertible promissory notes | Maximum
Borrowings
Interest rate (as a percent)	7%
2023 & 2024 convertible promissory notes
Borrowings
Amount outstanding	$ 5,000
2023 & 2024 convertible promissory notes | CVT Investors
Borrowings
Principal amount	$ 13,300
Interest rate (as a percent)	5%
Amount of debt converted	$ 13,400
Number of shares issued on conversion of debt | shares	2,004,535
Conversion price | $ / shares	$ 6.67
Amount outstanding	$ 0
2023 & 2024 convertible promissory notes | Strategic investor
Borrowings
Principal amount	$ 5,000		$ 5,000
Interest rate (as a percent)	5%
Term for conversion	6 months
Conversion price | $ / shares	$ 10

Debt - Borrowings Pursuant to T

Debt - Borrowings Pursuant to Term Loan and Security Agreements (Details) ₩ in Millions

1 Months Ended

3 Months Ended

12 Months Ended

Dec. 31, 2023 USD ($)

Jul. 31, 2016 USD ($)

Mar. 31, 2024 USD ($)

Dec. 31, 2021 USD ($)

Dec. 31, 2021 KRW (₩)

Dec. 31, 2022 USD ($)

Dec. 31, 2022 KRW (₩)

Dec. 31, 2017 USD ($)

Dec. 31, 2023 KRW (₩)

Dec. 31, 2022 KRW (₩)

Sep. 30, 2022 USD ($)

Sep. 30, 2022 KRW (₩)

May 31, 2022 USD ($)

May 31, 2022 KRW (₩)

Apr. 30, 2022 USD ($)

Apr. 30, 2022 KRW (₩)

Dec. 31, 2021 KRW (₩)

Oct. 31, 2021 USD ($)

Oct. 31, 2021 KRW (₩)

Jun. 30, 2021 USD ($)

Dec. 31, 2019

Dec. 31, 2017 KRW (₩)

Jan. 31, 2017 USD ($)

Jan. 31, 2017 KRW (₩)

Jul. 31, 2016 KRW (₩)

Borrowings

Amount outstanding

$ 79,856,000

$ 50,470,000

Borrowings

Borrowings

Amount outstanding

$ 39,840,000

KEB Hana Bank | Borrowings

Borrowings

Principal amount

$ 6,700,000,000

₩ 9,000

Annual interest rate

2.60%

5.20%

Additional extension term (in years)

1 year

Amount outstanding

6,980,000

$ 6,682,000

IBK Industrial Bank | Borrowings

Borrowings

Principal amount

$ 6,800,000

₩ 9,200

Interest rate (as a percent)

4.90%

Amount outstanding

7,135,000

$ 6,831,000

Note payable (one individual investor) | Borrowings

Borrowings

Principal amount

$ 1,000,000

Interest rate (as a percent)

4%

Amount of principal and interest outstanding

$ 1,100,000

Amount outstanding

1,000,000

1,000,000

M-Venture Investment, Inc. | Borrowings

Borrowings

Amount outstanding

7,756,000

$ 7,425,000

M-Venture Investment, Inc. | Term loan and security agreement, one

Borrowings

Principal amount

$ 3,700,000

₩ 5,000

Interest rate (as a percent)

6.50%

Amount outstanding

$ 3,100,000

$ 3,000,000

₩ 4,000

Amount repaid

$ 400,000

₩ 600

300,000

₩ 0.4

M-Venture Investment, Inc. | Term loan and security agreement, two

Borrowings

Amount outstanding

$ 4,800,000

M-Venture Investment, Inc. | Term loan and security agreement, two, draw one

Borrowings

Principal amount

$ 700,000

₩ 1,000

Interest rate (as a percent)

6.50%

M-Venture Investment, Inc. | Term loan and security agreement, two, draw two

Borrowings

Principal amount

$ 3,700,000

₩ 5,000

Interest rate (as a percent)

8.70%

Anapass, Inc, related party | Borrowings

Borrowings

Amount outstanding

10,082,000

$ 9,653,000

Anapass, Inc, related party | Term loan and security agreement, one

Borrowings

Principal amount

$ 4,500,000

₩ 6,000

Interest rate (as a percent)

5.50%

5.50%

Amount outstanding

$ 4,500,000

Anapass, Inc, related party | Term loan and security agreement, two

Borrowings

Interest rate (as a percent)

5.50%

Amount outstanding

$ 5,200,000

Anapass, Inc, related party | Term loan and security agreement, two, draw one

Borrowings

Principal amount

$ 2,200,000

₩ 3,000

Anapass, Inc, related party | Term loan and security agreement, two, draw two

Borrowings

Principal amount

$ 3,000,000

₩ 4,000

i Best Investment Co., Ltd | Borrowings

Borrowings

Principal amount

$ 10,300,000

$ 10,300,000

₩ 14,000

₩ 14,000

Interest rate (as a percent)

6.50%

6.50%

6.50%

6.50%

Amount outstanding

$ 10,082,000

7,425,000

i Best Investment Co., Ltd | Term loan and security agreement, draw one

Borrowings

Amount outstanding

3,300,000

i Best Investment Co., Ltd | Term loan and security agreement, draw two

Borrowings

Amount repaid

800,000

i Best Investment Co., Ltd | Term loan and security agreement, draw three

Borrowings

Amount outstanding

1,600,000

i Best Investment Co., Ltd | Term loan and security agreement, draw four

Borrowings

Amount repaid

2,300,000

i Best Investment Co., Ltd | Term loan and security agreement, draw five

Borrowings

Amount outstanding

2,300,000

i Best Investment Co., Ltd | Term loan and security agreement, draw six

Borrowings

Amount outstanding

800,000

Kyeongho Lee | Borrowings

Borrowings

Amount outstanding

$ 1,474,000

824,000

Kyeongho Lee | Promissory notes

Borrowings

Principal amount

400,000

$ 400,000

₩ 500,000

₩ 500,000

Amount outstanding

$ 700,000

Kyeongho Lee | Promissory notes | Minimum

Borrowings

Interest rate (as a percent)

9%

9%

9%

Kyeongho Lee | Promissory notes | Maximum

Borrowings

Interest rate (as a percent)

7.50%

7.50%

7.50%

Kyeongho Lee | Term loans

Borrowings

Principal amount

$ 100,000

$ 700,000

₩ 110,000

₩ 1,000

Interest rate (as a percent)

0%

Amount outstanding

$ 82,000

Commitments and Contingencies -

Commitments and Contingencies - Purchase Commitment (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Feb. 29, 2024
Purchase Commitment
Research and development expense	$ 5,521	$ 902	$ 10,712	$ 17,385
Unpaid recorded expenses included in accounts payable	1,242		17,814	19,017
Research and development agreement with Samsung
Purchase Commitment
Outstanding purchase commitments	0		0	500
Total fee amount	21,100		21,100
Fee amount to be paid over development milestones	11,700		11,700
Additional NRE to be paid as fee amount	$ 9,400		$ 9,400
Period for payment of additional NRE	4 years		4 years
Gain on release of unconditional liability	$ 14,600
Research and development expense			$ 400	7,100
Unpaid recorded expenses included in accounts payable			15,800	$ 15,400
Aggregated unpaid amount			$ 17,100
Research And Development Agreement With Alpha Holdings Co., Ltd
Purchase Commitment
Total fee amount					$ 7,600
Research and development expense	3,500
Aggregated unpaid amount	$ 5,000

Commitments and Contingencies_2

Commitments and Contingencies - Assets Pledged as Collateral (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Borrowings
Borrowings	$ 50,470	$ 79,856
Cash and cash equivalents	16,122	258	$ 1,398
Accounts receivable	5,103	4,920	4,453
Inventory	1,784	1,486	3,480
Property and equipment	644	772	1,111
KEB Hana Bank | Related party | Assets pledged as collateral | Borrowings
Borrowings
Borrowings	6,700	7,000	7,100
IBK Industrial Bank | Related party | Assets pledged as collateral | Borrowings
Borrowings
Borrowings	6,800	7,100	7,300
Anapass, Inc. | Related party | Assets pledged as collateral | Borrowings
Borrowings
Borrowings	9,700	10,100	10,300
Cash and cash equivalents	16,122	254	1,363
Accounts receivable	5,118	4,920	4,453
Inventory	1,784	1,486	3,480
Property and equipment	1,988	352	485
Intangible assets and others	$ 187	$ 199	$ 531

Common Stock (Details)

Common Stock (Details) - shares	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Common Stock
Total shares Authorized	440,000,000
Common stock, shares authorized	400,000,000	200,000,000	200,000,000
Preferred Stock, Shares Authorized	40,000,000	82,352,000

Common Stock - Shares authorize

Common Stock - Shares authorized (Details) - shares	Mar. 31, 2024	Dec. 31, 2023
Common Stock
Shares of authorized but unissued common stock	33,167,000	5,902,000
Warrants
Common Stock
Shares of authorized but unissued common stock	26,724,000	2,894,000
Shares available for future grant from 2024 plan
Common Stock
Shares of authorized but unissued common stock	3,983,000
Convertible promissory notes
Common Stock
Shares of authorized but unissued common stock	800,000	1,835,000
Options issued and outstanding
Common Stock
Shares of authorized but unissued common stock	668,000	668,000
Shares available for future grant from 2024 ESPP
Common Stock
Shares of authorized but unissued common stock	600,000
RSUs outstanding
Common Stock
Shares of authorized but unissued common stock	392,000	392,000
Shares available for grant from 2011 plan
Common Stock
Shares of authorized but unissued common stock		113,000
Shares available for future grant from 2011 plan
Common Stock
Shares of authorized but unissued common stock		113,000

Warrants (Details)

Warrants (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Warrants
Number of warrants issued	26,724,000
Number of warrants exercised		428,572
Number of warrants outstanding		9,200,000
Warrants expiration term	3 years
December 2020
Warrants
Number of warrants issued		2,514,285
Number of warrants expired/ cancelled		(2,514,285)
Exercise price of warrants		$ 3.50
Warrants expiration term		2 years
February 2021
Warrants
Number of warrants issued		342,857
Number of warrants expired/ cancelled		(342,857)
Exercise price of warrants		$ 3.50
Warrants expiration term		18 months
August 2021
Warrants
Number of warrants issued	299,000	999,997
Number of warrants outstanding		999,997
Exercise price of warrants		$ 3.50
Warrants expiration term		3 years
August 2021 | Maximum
Warrants
Exercise price of warrants	$ 18.75
August 2021 | Minimum
Warrants
Exercise price of warrants	$ 10
September 2021
Warrants
Number of warrants issued	300,000	428,571
Number of warrants outstanding		428,571
Exercise price of warrants	$ 5	$ 3.50
Warrants expiration term		3 years
February 2023 ~ June 2023
Warrants
Number of warrants issued	2,115,000	7,685,717
Number of warrants exercised		(428,572)
Number of warrants outstanding		7,257,145
Exercise price of warrants		$ 3.50
Warrants expiration term		3 years
February 2023 ~ June 2023 | Maximum
Warrants
Exercise price of warrants	$ 18.75
February 2023 ~ June 2023 | Minimum
Warrants
Exercise price of warrants	$ 10
July 2023
Warrants
Number of warrants issued	80,000	228,572
Number of warrants outstanding		228,572
Exercise price of warrants	$ 10	$ 3.50
Warrants expiration term		3 years
October 2023
Warrants
Number of warrants issued	100,000	285,715
Number of warrants outstanding		285,715
Exercise price of warrants	$ 10	$ 3.50
Warrants expiration term		3 years
:Public And Private Placement Warrants [Member]
Warrants
Number of warrants issued	23,830,000
Exercise price of warrants	$ 11.50

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - shares	1 Months Ended
	Sep. 30, 2011	Mar. 31, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares of common stock reserved for issuance	6,277,777
Additional shares of common stock reserved for issuance	265,597	90,000
Increase in shares reserved for issuance as percentage of total number of shares of common stock outstanding	5%
Maximum annual increase	2,500,000
2024 Incentive Compensation Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares of common stock reserved for issuance		3,983,334

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock option activities (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended			15 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2024
Number of Stock Options Outstanding
Balances as of beginning	392
Reverse recapitalization		(1,708)
Balances as of end	392	392			392
Weighted-Average Exercise Price
Balances as of beginning (in dollars per share)	$ 6.16
Reverse recapitalization (in dollars per share)		5.01
Balances as of end (in dollars per share)	$ 6.16	$ 6.16			$ 6.16
Stock Options
Shares Available for Grant
Balances as of beginning	605,826	2,641,679	1,679,763		2,641,679
Options granted		0	(105,000)		0
Cancelled		64,117	1,066,916
Balances as of end		605,826	2,641,679	1,679,763
Number of Stock Options Outstanding
Balances as of beginning	3,579,294	4,773,892	8,194,822		4,773,892
Granted		0	105,000		0
Exercised		(1,130,481)	(2,459,014)
Cancelled		(64,117)	(1,066,916)
Balances as of end	668,000	3,579,294	4,773,892	8,194,822	668,000
Vested as of end	667,000	3,311,859			667,000
Vested and expected to be vest as of end	634,000	3,569,024			634,000
Weighted-Average Exercise Price
Balances as of beginning (in dollars per share)	$ 0.02	$ 0.02	$ 0.02		$ 0.02
Granted (in dollars per share)			0.02
Exercised (in dollars per share)		0.02	0.02
Cancelled (in dollars per share)		0.02	0.02
Balances as of end (in dollars per share)	0.11	0.02	$ 0.02	$ 0.02	0.11
Vested as of end (in dollars per share)	0.11	0.02			0.11
Vested and expected to be vest as of end (in dollars per share)	$ 0.11	$ 0.02			$ 0.11
Weighted Average Remaining Contractual Life (Years)
Options Outstanding Weighted Average Remaining Contractual Life	5 years 3 months 18 days	5 years 6 months	5 years 1 month 6 days	6 years 1 month 6 days
Vested as of December 31, 2023	5 years 3 months 18 days	5 years 3 months 18 days
Vested and expected to be vest as of December 31, 2023	5 years 1 month 6 days	5 years 6 months
Balance as if beginning Aggregated Intrinsic Value	$ 5,543	$ 4,405			$ 5,543
Vested as of Aggregated Intrinsic Value	5,532				5,532
Exercisable as of Aggregated Intrinsic Value	$ 5,256				$ 5,256
Stock Options | Retrospectively adjusted
Number of Stock Options Outstanding
Balances as of beginning	668,000
Reverse recapitalization		(2,911,000)
Balances as of end		668,000
Weighted-Average Exercise Price
Balances as of beginning (in dollars per share)	$ 0.11
Reverse recapitalization (in dollars per share)		0.09
Balances as of end (in dollars per share)		$ 0.11
Weighted Average Remaining Contractual Life (Years)
Options Outstanding Weighted Average Remaining Contractual Life		5 years 6 months
Balance as if beginning Aggregated Intrinsic Value		$ 4,405
RSUs
Shares Available for Grant
RSUs granted		(2,099,970)
Number of Stock Options Outstanding
Balances as of beginning	2,100
Balances as of end		2,100
Weighted-Average Exercise Price
Balances as of beginning (in dollars per share)	$ 1.15
Balances as of end (in dollars per share)		$ 1.15

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
The Company and Summary of Significant Accounting Policies
stock-based compensation	$ 900,000
RSUs
The Company and Summary of Significant Accounting Policies
Unrecognized compensation cost related to RSUs	$ 2,100,000	$ 1,990,000
Expected weighted average period for recognition of unrecognized compensation cost related to RSUs	3 years 8 months 12 days	3 years 11 months 12 days
stock-based compensation	$ 300,000

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes
Income tax expense	$ 59,000	$ 50,000	$ 541,000	$ 121,000
Effective tax rate	7.20%	3.70%
Unrecognized tax benefits	$ 3,100,000		3,083,000	$ 3,203,000	$ 3,106,000
Unrecognized tax benefits effective tax rate	1,700,000		$ 1,700,000
Interest expense or penalties related to unrecognized tax benefits	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the unrecognized tax benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2024
Income Taxes
Beginning gross UTBs	$ 3,203,000	$ 3,106,000
Additions for tax positions taken in a prior year		(35,000)
Additions for tax provision taken in the current year	319,000	1,093,000
Adjustments for tax positions for changes in currency translation	95,000	(223,000)
Reductions for tax positions taken in the prior year	1,051,000	(270,000)
Reductions for tax positions taken in the prior year due to statutes lapsing	(1,585,000)	(468,000)
Ending gross UTBs	3,083,000	3,203,000
UTBs offset by deferred tax assets and/or valuation allowance	(1,419,000)	(1,714,000)
Net UTBs	1,664,000	1,489,000
Amount of unrecognized tax benefits that, if recognized, would affect effective tax rate	1,700,000		$ 1,700,000
Accrued interest and penalties	$ 522,000	$ 449,000

Employee Benefit Plans - Net li

Employee Benefit Plans - Net liability for severance payments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Employee Benefit Plans
Liability for severance payments, beginning	$ 7,764	$ 7,997	$ 7,248
Deposit	(276)	(308)	(343)
Liability for severance payments, ending	$ 7,488	$ 7,689	$ 6,905

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Related Party Transactions
Other	$ 107		$ 72	$ 104
Interest expense	2,082	$ 935	6,246	3,364
Related party | Anapass
Related Party Transactions
Borrowings	9,653		10,082	10,257
Other	106		212	11
Interest expense	100	100	548	389
Related party | Kyeongho Lee
Related Party Transactions
Borrowings	824		1,474	1,690
Other	87		182	150
Interest expense	$ 22,000	$ 26,000	$ 110	$ 140

Segments and Information (Detai

Segments and Information (Details) - segment	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Segments and Information
Number of operating segment	1	1

Segments and Information - Long

Segments and Information - Long-lived assets by geographic region (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segments and Geographical Information
Total long-lived assets	$ 1,987	$ 2,293	$ 1,921
United States
Segments and Geographical Information
Total long-lived assets	817	930	1,295
Korea
Segments and Geographical Information
Total long-lived assets	$ 1,170	$ 1,363	$ 626

Net Income (Loss) Per Share - C

Net Income (Loss) Per Share - Computation of basic and diluted net loss per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				12 Months Ended
	Mar. 31, 2024		Mar. 31, 2023		Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net income (loss), basic	$ 757		$ (1,393)		$ (22,469)	$ (28,649)
Net income (loss), diluted	$ 757		$ (1,393)
Denominator:
Weighted-average common shares outstanding, basic	25,468,000	[1]	23,862,000	[1]	128,459,102	92,958,570
Add: effect of dilutive securities	789,000
Weighted-average common shares outstanding, diluted	26,257,000	[1]	23,862,000	[1]	128,459,102	92,958,570
Net income (loss) per share, basic and diluted
Net income (loss) per common share - basic	$ 0.03	[1]	$ (0.06)	[1]	$ (0.17)	$ (0.31)
Net income (loss) per common share - diluted	$ 0.03	[1]	$ (0.06)	[1]	$ (0.17)	$ (0.31)
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

Net Income (Loss) Per Share -_2

Net Income (Loss) Per Share - Computation of outstanding potentially dilutive common stock (Details) - shares	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities that were excluded from the computation of diluted net loss per common share	32,267,000	3,689,000	24,706,930	18,405,485
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities that were excluded from the computation of diluted net loss per common share	26,724,000	995,000	9,200,000	3,942,853
Convertible promissory notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities that were excluded from the computation of diluted net loss per common share	5,543,000	1,809,000
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities that were excluded from the computation of diluted net loss per common share		885,000	3,579,294	4,773,892

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent event $ in Millions, ₩ in Billions	1 Months Ended
	May 31, 2024 shares	Apr. 30, 2024 USD ($)	Apr. 30, 2024 KRW (₩)	Apr. 30, 2024 KRW (₩)
Historical convertible promissory notes notes.
Subsequent Events
Principal amount | $		$ 0.6
Share Reserve
Subsequent Events
Maximum number of shares of Common stock | shares	3,983,334
Share Reserve | ESPP 2024
Subsequent Events
Reserve share | shares	600,000
M-Venture Investment, Inc.
Subsequent Events
Term loan outstanding		3		₩ 4
Principal amount of loan extended maturity date from April 2024 to June 2024		0.7		1
M-Venture Investment, Inc. | Term loans
Subsequent Events
Term loan outstanding		4.4		6
Repayment of short term loan		1.5	₩ 2
Principal amount of loan extended maturity date from April 2024 to July 2024		$ 3.7		₩ 5
B. Riley Principal Capital II, LLC
Subsequent Events
Period for issuance of stock		24 months	24 months
Common stock purchase agreement | B. Riley Principal Capital II, LLC
Subsequent Events
Maximum aggregate amount of stock issuance | $		$ 50

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS $ in Thousands	Dec. 31, 2022 USD ($)
Current assets:
Cash and cash equivalents	$ 1,398
Accounts receivable, net	4,453
Inventory	3,480
Contract assets	886
Prepaid expenses and other current assets	2,673
Total current assets	12,890
Property and equipment, net	1,111
Operating lease right-of-use assets	796
Finance lease right-of-use assets	14
Intangibles, net	672
Other assets	993
Total assets	16,476
Current liabilities:
Accounts payable	19,017
Contract liabilities	651
Accrued and other current liabilities	12,496
Borrowings	18,331
Convertible promissory notes, current	31,166
Operating lease liabilities, current	228
Finance lease liabilities, current	17
Total current liabilities	81,906
Long-term borrowings	20,025
Net defined benefit liabilities	6,905
Long-term operating lease liabilities	570
Income taxes payable	1,923
Other liabilities	76
Total liabilities	111,405
Stockholders' deficit:
Common stock, par value $0.001 per share, 200,000,000 shares authorized; 129,395,774 and 127,760,265 shares issued and outstanding as of December 31, 2023 and 2022, respectively	128
Additional paid-in capital	433,990
Accumulated other comprehensive loss	(1,862)
Accumulated deficit	(527,185)
Total stockholders' deficit	(94,929)	[1]
Total liabilities and stockholders' deficit	$ 16,476
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2024	Mar. 26, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Consolidated Balance Sheets
Common stock, par value per share	$ 0.0001		$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000		200,000,000	200,000,000
Common stock, shares issued	45,833,000	45,833,000	24,166,000	127,760,265
Common stock, shares outstanding	45,833,000		24,166,000	24,166,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	3 Months Ended				12 Months Ended
	Mar. 31, 2024		Mar. 31, 2023		Dec. 31, 2023	Dec. 31, 2022
Net revenues
Total net revenues	$ 3,265,000		$ 3,062,000		$ 16,028,000	$ 16,669,000
Cost of net revenues
Total cost of net revenues	1,312,000		1,541,000		9,294,000	11,616,000
Gross profit	1,953,000		1,521,000		6,734,000	5,053,000
Operating expenses:
Research and development	5,521,000		902,000		10,712,000	17,385,000
Sales and marketing	996,000		836,000		3,188,000	2,836,000
General and administrative	2,836,000		1,477,000		7,392,000	7,585,000
Total operating expenses					21,292,000	27,806,000
Income (loss) from operations	7,236,000		(1,694,000)		(14,558,000)	(22,753,000)
Interest income					8,000	4,000
Interest expense	(2,082,000)		(935,000)		(6,246,000)	(3,364,000)
Other income (expense), net	(4,338,000)		1,286,000		(1,132,000)	(178,000)
Income (loss) before provision for income taxes	816,000		(1,343,000)		(21,928,000)	(26,291,000)
Provision for income taxes	59,000		50,000		541,000	121,000
Net income (loss)	757,000		(1,393,000)		(22,469,000)	(26,412,000)
Accretion of Series G redeemable convertible preferred stock to redemption amount					0	(2,237,000)
Net loss attributable to common stockholders	757,000		(1,393,000)		$ (22,469,000)	$ (28,649,000)
Net loss attributable to common stockholders - diluted	$ 757,000		$ (1,393,000)
Net loss per common share - basic	$ 0.03	[1]	$ (0.06)	[1]	$ (0.17)	$ (0.31)
Net loss per common share - diluted	$ 0.03	[1]	$ (0.06)	[1]	$ (0.17)	$ (0.31)
Weighted average number of common shares used in computing net loss per common share - basic	25,468,000	[1]	23,862,000	[1]	128,459,102	92,958,570
Weighted average number of common shares used in computing net loss per common share - diluted	26,257,000	[1]	23,862,000	[1]	128,459,102	92,958,570
Product
Net revenues
Total net revenues	$ 2,378,000		$ 599,000		$ 10,968,000	$ 12,977,000
Cost of net revenues
Total cost of net revenues	654,000		978,000		7,343,000	10,250,000
Service
Net revenues
Total net revenues	887,000		2,463,000		5,060,000	3,692,000
Cost of net revenues
Total cost of net revenues	$ 658,000		$ 563,000		$ 1,951,000	$ 1,366,000
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Comprehensive loss, net of taxes
Net loss	$ 757	$ (1,393)	$ (22,469)	$ (26,412)
Foreign currency translation adjustment	1,064	674	324	1,583
Comprehensive income (loss)	$ 1,821	$ (719)	$ (22,145)	$ (24,829)

CONSOLIDATED STATEMENTS OF REDE

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' DEFICIT - USD ($) $ in Thousands		Common Stock		Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance as at beginning at Dec. 31, 2021							$ 382,288
Balance as at beginning (in shares) at Dec. 31, 2021							73,259,663
Increase (Decrease) in Redeemable Convertible Preferred Stock [Roll Forward]
Accretion of Series G redeemable convertible preferred stock to redemption amount							$ 2,237
Conversion of redeemable convertible preferred stock to common stock							$ (384,525)
Conversion of redeemable convertible preferred stock to common stock (in shares)							(73,259,663)
Balance as at end (in shares) at Dec. 31, 2022	[1]	23,861,000
Balance as at beginning at Dec. 31, 2021		$ 13		$ 13,682	$ (3,445)	$ (498,536)	$ (488,286)
Balance as at beginning (in shares) at Dec. 31, 2021		13,183,259
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of Series G redeemable convertible preferred stock to redemption amount						(2,237)	(2,237)
Conversion of redeemable convertible preferred stock to common stock		$ 74		384,451			384,525
Conversion of redeemable convertible preferred stock to common stock (in shares)		73,203,888
Common stock dividends issued to Series C and Series G redeemable convertible preferred stock		$ 29		(29)
Common stock dividends issued to Series C and Series G redeemable convertible preferred stock (in shares)		28,685,582
Issuance of common stock from option exercises		$ 2		49			51
Issuance of common stock from option exercises (in shares)		2,459,014
Issuance of common stock from conversion of convertible promissory notes and accrued interest		$ 10		35,820			35,830
Issuance of common stock from conversion of convertible promissory notes and accrued interest (in shares)		10,228,522
Stock-based compensation				17			17
Foreign currency translation adjustment					1,583		1,583
Net loss						(26,412)	(26,412)
Balance as at end at Dec. 31, 2022	[1]	$ 2		434,116	(1,862)	(527,185)	$ (94,929)
Balance as at end (in shares) at Dec. 31, 2022							127,760,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from option exercises	[1]			1			$ 1
Issuance of common stock from option exercises (in shares)	[1]	5,000
Stock-based compensation	[1]			2			2
Foreign currency translation adjustment					674		674
Net loss						(1,393)	(1,393)
Balance as at end at Mar. 31, 2023		$ 2		434,119	(1,188)	(528,578)	(95,645)
Balance as at end (in shares) at Mar. 31, 2023		23,866,000
Balance as at beginning (in shares) at Dec. 31, 2022	[1]	23,861,000
Balance as at beginning at Dec. 31, 2022	[1]	$ 2		434,116	(1,862)	(527,185)	$ (94,929)
Balance as at beginning (in shares) at Dec. 31, 2022							127,760,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of Series G redeemable convertible preferred stock to redemption amount							$ 0
Issuance of common stock from option exercises		$ 1		22			23
Issuance of common stock from option exercises (in shares)		1,130,481
Issuance of common stock from conversion of convertible promissory notes and accrued interest				72			72
Issuance of common stock from conversion of convertible promissory notes and accrued interest (in shares)		20,681
Issuance of common stock from cancellation of promissory note		55,775
Issuance of common stock from warrant exercise				1,499			1,499
Issuance of common stock from warrant exercise (in shares)		428,572
Stock-based compensation				43			43
Foreign currency translation adjustment					324		324
Net loss						(22,469)	(22,469)
Balance as at end at Dec. 31, 2023	[1]	$ 3		435,752	(1,538)	(549,654)	$ (115,437)
Balance as at end (in shares) at Dec. 31, 2023		24,166,000	[1]				24,166,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation				1,223			$ 1,223
Foreign currency translation adjustment					1,064		1,064
Net loss						757	757
Balance as at end at Mar. 31, 2024		$ 5		$ 487,006	$ (474)	$ (548,897)	$ (62,360)
Balance as at end (in shares) at Mar. 31, 2024		45,833,000					45,833,000
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (22,469)	$ (26,412)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,062	781
Operating lease right-of-use amortization	714	766
Finance lease right-of-use amortization	14	18
Stock-based compensation	43	17
Provision for credit losses	1,095	549
Loss on valuation of convertible promissory notes	1,428	450
Loss on redemption of convertible promissory notes		40
Changes in operating assets and liabilities:
Accounts receivable	(1,562)	858
Inventory	1,994	(1,772)
Contract assets	(2,553)	(225)
Prepaid expenses and other current assets	(233)	1,150
Other assets	112	4
Accounts payable	296	6,145
Contract liabilities	(603)	(116)
Accrued and other current liabilities	11,471	1,772
Net defined benefit liabilities	784	(699)
Income taxes payable	255	57
Lease liabilities	(707)	(791)
Other liabilities	32	(661)
Net cash used in operating activities	(8,827)	(18,087)
Cash flows from investing activities:
Purchase of property and equipment	(331)	(623)
Purchase of intangibles		(280)
Net cash used in investing activities	(331)	(903)
Cash flows from financing activities:
Proceeds from bank borrowings	8,147	13,414
Proceeds from exercise of stock options	23	51
Proceeds from issuance of convertible promissory note	2,000	9,000
Repayment of bank borrowings	(1,504)	(1,988)
Repayment of convertible promissory note	(500)	(1,180)
Payments of finance lease liabilities	(17)	(24)
Net cash provided by financing activities	8,149	19,273
Effect of exchange rate changes on cash and cash equivalents	(131)	(136)
Net increase (decrease) in cash and cash equivalents	(1,140)	147
Cash and cash equivalents at beginning of year	1,398	1,251
Cash and cash equivalents cash at end of year	258	1,398
Supplemental disclosures of cash flow information:
Cash paid for interest	2,259	4,175
Cash paid for income taxes	116	333
Noncash financing activities:
Accretion of Series G redeemable convertible preferred stock to redemption amount		2,237
Issuance of common stock from conversion of convertible promissory notes and accrued interest	72	35,830
Issuance of common stock from cashless warrant exercise	$ 1,499
Conversion of redeemable convertible preferred stock to common stock		$ 384,525

The Company and Summary of Sign

The Company and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Organization and Liquidity
The Company and Summary of Significant Accounting Policies	1. The Company and Summary of Significant Accounting Policies Business GCT Semiconductor, Inc. (“GCT”) is a fabless semiconductor company that designs, develops and markets integrated circuits for the global wireless semiconductor industry. GCT was originally incorporated in California on June 15, 1998 and was reincorporated in Delaware on February 21, 2001. In June 2000, GCT incorporated a wholly-owned subsidiary, GCT Asia Pacific, Inc. (“GCT AP”) in Seoul, South Korea. GCT AP was created to develop markets in the Asia Pacific region. In June 2000, GCT acquired Advanced CoreTech, Inc. (“ACT”), a South Korean corporation, to enhance its research and development (“R&D”) capacity for all product lines. Subsequent to the acquisition, ACT changed its name to GCT Research, Inc. (“GCT R&D”). In October 2012, GCT acquired MTH, Inc. (“MTH”), a South Korean corporation, to acquire 2G/3G LTE technology and further enhance research and development. To date, GCT and its wholly-owned subsidiaries’, GCT AP, GCT R&D and MTH (collectively, the “Company”) operations have been funded primarily through the issuance of redeemable convertible preferred stock, promissory notes, bank borrowings and issuance of common stock. On November 2, 2023, the Company entered into a definitive business combination agreement with Concord Acquisition Corp III, a publicly traded special purpose acquisition company, that would result in the Company becoming a publicly listed company subject to closing. Upon closing of the transaction, the combined company will be named GCT Semiconductor and will be traded on the NYSE under the new ticker symbol “GCTS.” The transaction is expected to be completed in the first quarter of 2024. Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) Principles of Consolidation The accompanying consolidated financial statements include the accounts of GCT and its wholly-owned subsidiaries, GCT AP, GCT R&D and MTH. All significant intercompany balances and transactions have been eliminated in consolidation. Net Loss Per Common Share Basic net loss per common share is computed by dividing net loss attributable to common stockholders (net loss adjusted for preferred stock dividends declared or accumulated) by the weighted average number of common shares outstanding during the period. All participating securities are excluded from basic weighted average shares outstanding. In computing diluted net loss attributable to common stockholders, undistributed earnings are re-allocated to reflect the potential impact of dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing net loss attributable to common stockholders by diluted weighted average shares outstanding, including potentially dilutive securities, unless anti-dilutive. Potentially dilutive securities that were excluded from the computation of diluted net loss per common share consist of the following: ​ 1. The Company and Summary of Significant Accounting Policies Net Loss Per Common Share ​ ​ ​ ​ ​ ​ ​ 2023 2022 Convertible promissory notes 9,827,666 9,688,740 Warrants 9,200,000 3,942,853 Options 3,579,294 4,773,892 Restricted Stock Units (RSU) 2,099,970 — Total 24,706,930 18,405,485 ​ As all potentially dilutive securities are anti-dilutive as of December 31, 2023 and 2022, diluted net loss per common share is the same as basic net loss per common share for each period. Use of Estimates The preparation of the accompanying consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates, and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. These judgments, estimates and assumptions are used for but not limited to: revenue recognition; provision for credit losses; warranty obligations; inventory obsolescence; recoverability of long-lived assets; stock-based compensation; determination of fair value of the Company’s convertible promissory notes, common stock, and stock options, and deferred income taxes including related valuation allowances. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates, and these differences may be material. Going Concern, Liquidity and Management’s Plan The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Company has incurred operating losses and negative cash flows from operating activities for each of the two years in the period ended December 31, 2023. As of December 31, 2023, the Company had an accumulated deficit of approximately $549.7 million and negative working capital of approximately $101.8 million. During the year ended December 31, 2023, the Company incurred a net loss of approximately $22.5 million and used cash from operations of approximately $8.8 million. These factors raise substantial doubt about the Company’s ability to continue as a going concern for the twelve months from the date of this report. The Company’s ability to continue to meet its obligations and to achieve its intended business objectives is dependent upon, among other things, negotiating a bank line of credit debt obligation, raising additional capital, and the timely launch of its new products and returning to profitability. Future capital requirements will depend on many factors, including the rate of revenue growth, the selling price of the Company’s products, the expansion of sales and marketing activities, and the timing and extent of research and development efforts. ​ 1. The Company and Summary of Significant Accounting Policies, Going Concern, Liquidity and Management’s Plan The Company is actively pursuing a transaction with a special purpose acquisition company (“SPAC”) and completed major steps required including the U.S. Security and Exchange Commission (“SEC”) filing and SPAC shareholders’ approval. Management expects the SPAC transaction will be successful and could use the proceeds from the SPAC transaction to support its operations. In the event the proceeds from the SPAC transaction are not enough, the Company will seek additional funding through other means, such as the issuance of debt or equity line of credit. Management’s plans also include managing the Company’s cash burn by controlling expenditures. While the Company has raised capital in the past, there can be no assurance that additional financing will be available at terms acceptable to the Company, if at all. Failure to generate sufficient cash flows from operations, raise additional capital and reduce discretionary spending could have a material adverse effect on the Company’s ability to achieve its intended business objectives. The accompanying consolidated financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern. Cash and Cash Equivalents The Company considers all highly liquid investments purchased with a remaining maturity of three months or less to be cash equivalents. The Company deposits its cash primarily in checking and money market accounts with high quality financial institutions. Fair Value of Financial Instruments The carrying amount of certain financial instruments held by the Company, such as cash equivalents, accounts receivable, contract assets and liabilities, accounts payable, and accrued and other current liabilities, approximate fair value due to their short maturities. The carrying amount of the liabilities for the convertible promissory notes represents their fair value. The carrying amounts of the Company’s bank borrowings, and lease liabilities approximate fair value due to the market interest rates that these obligations bear and interest rates currently available to the Company. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities; Level 2 Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. ​ 1. The Company and Summary of Significant Accounting Policies Fair Value of Financial Instruments The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company has no assets with fair value obtained using observable or unobservable markets. The Company did have liabilities with a fair value obtained using unobservable markets (Level 3). The Company’s Level 3 liabilities consist of the redeemable convertible preferred stock warrant liabilities and convertible promissory notes. The convertible promissory notes were valued using a combination of option pricing model and Probability Weighted Expected Return Method (“PWERM”), which is considered to be a Level 3 fair value measurement. Risk and Uncertainties The Company is subject to certain risks and uncertainties and believes changes in any of the following areas could have a material adverse effect on the Company’s future financial position or results of operations or cash flows: new product development, including market receptivity, litigation or claims against the Company based on intellectual property, patent, product regulation or other factors, competition from other products, general economic conditions, the ability to attract and retain qualified employees and ultimately to sustain profitable operations. The semiconductor industry is characterized by rapid technological change, competition, competitive pricing pressures and cyclical market patterns. The Company’s financial results are affected by a wide variety of factors, such as general economic conditions specific to the semiconductor industry and the Company’s particular market, the timely implementation of new products, new manufacturing process technologies and the ability to safeguard patents and intellectual property in a rapidly evolving market. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns. As a result, the Company may experience significant period-to-period fluctuations in consolidated operating results due to the factors mentioned above or other factors. The Company’s revenue may be impacted by its ability to obtain adequate wafer supplies from foundries and back-end production capacity from the Company’s test and assembly subcontractors. The foundries with which the Company currently has arrangements may not be willing or able to satisfy all of the Company’s manufacturing requirements on a timely basis and/or at favorable prices. The Company is also subject to the risks of service disruptions, raw material shortages and price increases by its foundries. Such disruptions, shortages and price increases could harm the Company’s consolidated operating results. ​ 1. The Company and Summary of Significant Accounting Policies Concentration Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash and cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents primarily with one financial institution located in the United States and another financial institution located in Korea where amounts deposited may exceed Federal Deposit Insurance Corporation or Korea Deposit Insurance Corporation limits. The Company’s accounts receivable are primarily derived from revenues earned from customers located in the United States, China, Korea, Japan and Taiwan. The Company performs ongoing credit evaluations of its customers’ and distributors’ financial condition and generally does not require collateral from its customers. Some of the components used in the Company’s products are purchased from a limited number of sources located in Asia. The loss of any of these suppliers may cause the Company to incur additional costs to transition these relationships, result in delays in the delivery of its products or cause the Company to carry excess or obsolete inventory. GCT is a fabless semiconductor company and relies on third parties for all of its manufacturing operations, including wafer fabrication, assembly, testing, warehousing, and shipping and logistics. The Company relies on UMC Company (USA) (“UMC”) and Samsung Semiconductor System LSI Division to manufacture substantially all of the wafers for its products. The Company uses third-party vendors to assemble, package and test the products. The Company primarily uses the services of Tianshui Huatian Co., Ltd., ATSemicon Co., Ltd. Amkor, and STATS ChipPAC Ltd. for assembly, and Advanced Semiconductor and Engineering, Inc. and Giga Solution Tech Co., Ltd. for testing. The Company depends on these third-party vendors to supply services and material of a requested quantity in a timely manner that meets the Company’s standards for yield, cost and manufacturing quality. The Company does not have long-term supply agreements with its third-party vendors other than a framework agreement with UMC. If one or more of these vendors terminates its relationship with the Company, or if the Company encounters any problems with its manufacturing supply chain, it could adversely impact the Company’s ability to ship products to its customers on time and in the quantity required, which in turn could cause an unanticipated decline in sales and possibly damage customer relationships. Accounts Receivable and Provision for Credit Losses Trade accounts receivable are recorded at invoiced amounts, net of provision for credit losses, if applicable, and do not bear interest. The provision for credit losses is based on the Company’s assessment of the collectability of its customer accounts. The Company reviews the provision for credit losses by considering certain factors such as historical experience, industry data, credit quality, age of balances and current economic conditions that may affect a customer’s ability to pay. Uncollectible receivables are written off when all efforts to collect have been exhausted and recoveries are recognized when they are recovered. The Company determined that provisions for credit losses of approximately $1,644,000 and $549,000 were necessary as of December 31, 2023 and 2022, respectively. ​ 1. The Company and Summary of Significant Accounting Policies Inventory Inventory is stated at the lower of cost or net realizable value. Cost is determined by actual cost on a first-in, first-out basis. The Company’s inventory is concentrated in high technology parts and components that may be specialized in nature or subject to rapid technological obsolescence. The Company considers the following characteristics, in addition to the specialized nature and potential technological obsolescence of the Company’s inventory, including age of inventory on hand and that the inventory may be returned from distributors, historical sales levels, estimated future demand within the next six months, inventory commitments or potential product revisions, in evaluating net realizable value. For the years ended December 31, 2023 and 2022, the Company wrote-down approximately $358,000 and $338,000, respectively, of inventory into cost of net revenues. Once inventory has been written down below cost, it is not subsequently written up. Property and Equipment, Net Property and equipment are recorded at cost less accumulated depreciation and amortization. Depreciation is recognized on a straight-line basis over the estimated useful lives of the assets, generally three Leases The Company is a lessee in several noncancellable (1) operating leases, primarily for office equipment, warehouses, and office space, and (2) finance leases, for certain machinery and information technology (“IT”) equipment. The Company accounts for leases in accordance with the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) Topic 842, Leases (“Topic 842”). The Company determines if an arrangement is or contains a lease at contract inception. The Company recognizes a right-of-use (“ROU”) asset and a lease liability at the lease commencement date. For operating and finance leases, the lease liability is initially measured at the present value of the unpaid lease payments at the lease commencement date. The lease liability is subsequently measured at amortized cost using the effective-interest method. Key estimates and judgments include how the Company determines (1) the discount rate it uses to discount the unpaid lease payments to present value, (2) lease term, and (3) lease payments. ● 1. The Company and Summary of Significant Accounting Policies Leases ● ● – – – – The ROU asset is initially measured at cost, which comprises the initial amount of the lease liability adjusted for lease payments made at or before the lease commencement date, plus any initial direct costs incurred less any lease incentives received. For operating leases, the ROU asset is subsequently measured throughout the lease term at the carrying amount of the lease liability, plus initial direct costs, plus (minus) any prepaid (accrued) lease payments, less the unamortized balance of lease incentives received. Lease expense for lease payments is recognized on a straight-line basis over the lease term. For finance leases, the ROU asset is subsequently amortized using the straight-line method from the lease commencement date to the earlier of the end of its useful life or the end of the lease term unless the lease transfers ownership of the underlying asset to the Company or the Company is reasonably certain to exercise an option to purchase the underlying asset. In those cases, the ROU asset is amortized over the useful life of the underlying asset. Amortization of the ROU asset is recognized and presented separately from interest expense on the lease liability. Variable lease payments associated with the Company’s leases are recognized when the event, activity, or circumstance in the lease agreement on which those payments are assessed occurs. Variable lease payments are presented as operating expenses in the Company’s consolidated statements of operations in the same line item as expenses arising from fixed lease payments (operating leases) or amortization of the ROU asset (finance leases). ROU assets for operating and finance leases are occasionally reduced by impairment losses. The Company uses the long-lived assets impairment guidance in ASC Subtopic 360-10, Property, Plant, and Equipment – Overall, to determine whether an ROU asset is impaired, and if so, the amount of the impairment loss to recognize. The Company monitors for events or changes in circumstances that require a reassessment of one of its leases. When a reassessment results in the remeasurement of a lease liability, a corresponding adjustment is made to the carrying amount of the corresponding ROU asset unless doing so would reduce the carrying amount of the ROU asset to an amount less than zero. In that case, the ROU asset is reduced to zero and the remainder of the adjustment is recorded in profit or loss. 1. The Company and Summary of Significant Accounting Policies Leases Operating lease and finance lease ROU assets are presented as operating lease right-of-use assets and finance lease right-of use assets, respectively, on the consolidated balance sheets. The current portion of finance lease liabilities is included in current installments of obligations under finance leases, and the long-term portion is included in obligations under finance leases on the consolidated balance sheets. The Company has elected not to recognize ROU assets and lease liabilities for short-term leases of transportation equipment that have a lease term of 12 months or less. The Company has elected not to apply the short-term lease recognition and measurement exemption for other classes of leased assets. The Company recognizes the lease payments associated with its short-term transportation equipment leases as an expense on a straight-line basis over the lease term. Variable lease payments associated with these leases are recognized and presented in the same manner as for all other Company leases. The Company’s leases generally include non-lease maintenance services (i.e. equipment maintenance or common area maintenance). For leases of assets other than office equipment, the Company allocates the consideration in the contract to the lease and non-lease maintenance component based on each component’s relative stand-alone price. The Company determines stand-alone prices for the lease components in those leases based on the prices for which other lessors lease similar assets on a stand-alone basis. The Company determines stand-alone prices for the non-lease components (i.e. maintenance services) in those leases based on the prices that several suppliers charge for maintenance services for similar assets on a stand-alone basis. If observable stand-alone prices are not readily available, the Company estimates the stand-alone prices maximizing the use of observable information. For leases of office equipment, the Company has elected the practical expedient to account for the lease and non-lease maintenance components as a single lease component. Therefore, for those leases, the lease payments used to measure the lease liability include all the fixed consideration in the contract. Impairment of Long-Lived Assets The Company has long-lived assets such as tangible property and equipment, and identified intangible assets consisting of acquired patents and core technology. When events or changes in circumstances occur that could indicate the carrying value of long-lived assets may not be recoverable, the Company assesses recoverability by determining whether the undiscounted cash flows estimated to be generated by those assets are less than the carrying amounts of those assets. If the undiscounted cash flow is less, an impairment charge is recognized for the excess of the carrying amounts of these assets over the fair values. Fair values are determined by discounted future cash flows, appraisals or other methods. During the years ended December 31, 2023 and 2022, the Company did not record any impairment from long-lived assets. ​ 1. The Company and Summary of Significant Accounting Policies Revenue Recognition The Company’s revenues are generated by the sale of 4G mobile semiconductor solutions consisting of product and platform solutions aimed at the 4G LTE and WiMax industries, development services and technical advice and maintenance services. To determine when revenues are recognized, the Company performs the following five steps: (1) identify the contract(s) with a customer, (2) identify the performance obligation in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) we satisfy a performance obligation in accordance with ASC Topic 606, Revenue from Contracts with Customers. The revenues from product sales are identified and determined pursuant to purchase orders. The Company considers a performance obligation satisfied once it has transferred control of a good or product to a customer, meaning the customer has the ability to direct the use and obtain the benefit of the product, which is generally at the time of shipment. Service revenues are identified and determined based on each service agreement and recognized over time or at a point in time depending on the evaluation of when the customer obtains control of the promised goods or services, which is generally as services are rendered. For contracts that include multiple performance obligations, the Company allocates revenue to each performance obligation based on estimates of the relative stand-alone selling price that the Company would charge the customer for each promised product or service. Disaggregation of revenues from contracts with customers is as following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2023 (in thousands) ​ Product Revenues ​ Service Revenues ​ Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 10,968 ​ $ — ​ $ 10,968 Over time ​ — ​ 5,060 ​ 5,060 Total ​ $ 10,968 ​ $ 5,060 ​ $ 16,028 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2022 (in thousands) Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 12,977 ​ $ — ​ $ 12,977 Over time ​ — ​ 3,692 ​ 3,692 Total ​ $ 12,977 ​ $ 3,692 ​ $ 16,669 ​ ​ 1. The Company and Summary of Significant Accounting Policies Revenue Recognition Net revenues categorized by customer location are as follows for the years ended December 31: ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues from external customers (in thousands) ​ 2023 ​ 2022 United States $ 5,056 $ 4,379 China ​ 4,745 ​ 5,608 Korea ​ 4,260 ​ 1,360 Germany ​ 1,422 ​ — Taiwan ​ 543 ​ 4,639 Other ​ 2 ​ 25 Singapore ​ — ​ 658 Total ​ $ 16,028 ​ $ 16,669 ​ Contract Assets and Liabilities Contract assets primarily represent revenue earnings over time for which the Company does not presently have an unconditional right to payment (generally not yet billable) based on the terms of the contracts. The Company does not have impairment losses associated with contracts with customers for the years ended December 31, 2023 and 2022. Contract liabilities consist of fees invoiced to or paid by the Company’s customer for which the associated performance obligations have not been satisfied and revenue has not been recognized based on the Company’s revenue recognition criteria described above. Contract assets and liabilities are reported in a net position on an individual contract basis at the end of each reporting period. Contract assets are classified as current in the consolidated balance sheets when the Company expects to complete the related performance obligations and invoice the customers within one year of the balance sheet date, and as long-term when the Company expects to complete the related performance obligations and invoice the customers more than one year out from the balance sheet date. Contract liabilities are classified as current in the consolidated balance sheets when the revenue recognition associated with the related customer payments and invoicing is expected to occur within one year of the balance sheet date and as long-term when the revenue recognition associated with the related customer payments and invoicing is expected in more than once year from the balance sheet date. Details of contract assets and liabilities is as following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ December 31, 2023 ​ December 31, 2022 Contract assets ​ $ 3,439 ​ $ 886 Assets recognized for costs incurred to fulfill a contract (*) ​ 12 ​ 39 Contract liabilities ​ 48 ​ 651 (*)- The balances are included in prepaid expenses and other current assets in the accompanying consolidated balance sheets. As of January 1, 2022, contract assets were approximately $661,000. ​ 1. The Company and Summary of Significant Accounting Policies Revenue Recognition Assets recognized for costs incurred to fulfill a contract represent costs incurred in relation to a contract development and are intended for use in fulfilling that contract. The costs relate directly to the contract, generate resources that will be used to satisfy the contract and are expected to be recovered. They were therefore recognized as assets from costs to fulfill a contract. The asset is amortized on the basis consistent with the method used in recognizing revenue for the specific contract it relates to. In the current period, management expected that the costs recognized as assets are to be recovered according to the contractual payment schedule. Thus, an impairment loss was not recognized as the expected amount of the remaining consideration minus direct costs which have not been recognized as expenses do not exceed the asset. During the year ended December 31, 2023, there were significant changes in contract assets and liabilities, which are summarized as below: ● ● ● Net revenues recognized in relation to contract liabilities is as follows. ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) December 31, 2023 December 31, 2022 Net revenues recognized that were included in the contract liabilities balance at the beginning of the year ​ $ 651 ​ $ 766 ​ Product Warranty The Company provides customers with warranty claims for certain products and warranty-related the services are not considered a separate performance obligation. Pursuant to ASC Topic 450, Contingencies, the Company makes estimates of product warranty expense using historical experience rates and accrue estimated warranty expense as a cost of net revenues. The Company estimates the costs of warranty obligations based on historical experience of known product failure rates and anticipated rates of warranty claims, use of materials to repair or replace defective products, and service delivery costs incurred in correcting the product issues. In addition, from time to time, specific warranty accruals may be made if unforeseen technical problems arise. ​ 1. The Company and Summary of Significant Accounting Policies Concentration of Revenues and Accounts Receivable The Company’s net revenue and accounts receivable are concentrated among a few significant customers, which could expose the Company to financial risk in the event of adverse developments with these customers. In fiscal 2023, approximately 38% of the Company’s total net revenues were derived from two customers. Moreover, approximately 70% of the total gross accounts receivable was derived from four customers at the end of the reporting period. During fiscal 2022, around 66% of the Company’s total net revenues were derived from four customers. Similar to the concentration of revenue, approximately 90% of the total gross accounts receivable was derived from five customers at the end of the reporting period. Details of external customers, who contribute more than 10% of the Company’s net revenues and gross accounts receivable as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Revenues ​ Accounts Receivable (in thousands) ​ 2023 ​ 2022 ​ 2023 ​ 2022 Customer A $ * $ 4,639 $ * $ 1,228 Customer B ​ 3,031 ​ 2,979 ​ 1,755 ​ 590 Customer C ​ * ​ 1,712 ​ * ​ 1,400 Customer D ​ * ​ 1,670 ​ 661 ​ 687 Customer E ​ * ​ * ​ * ​ 610 Customer F ​ * ​ * ​ 1,250 ​ * Customer G ​ 3,000 ​ * ​ * ​ * Customer H ​ * ​ * ​ 938 ​ * *Less than 10% Management closely monitors the creditworthiness and performance of these key customers and has established credit limits and terms to mitigate potential credit risks. The Company also continues to diversify its customer base and explore opportunities to reduce its reliance on a few major customers. Cost of Net Revenues Cost of net revenues consists of direct and indirect costs related to the manufacture of the Company’s products. Direct costs include wafer costs and costs relating to assembly and testing performed by third-party contract manufacturers. Indirect costs consist of provisions for excess and obsolete inventory, royalties, allocated overhead for employee costs and facility costs, warranty and the amortization of the Company’s production mask sets and certain intangible assets. Shipping and handling costs incurred for inventory purchases and product shipments are recorded in cost of net revenues in the consolidated statement

Fair Value of Measurements_2

Fair Value of Measurements	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value of Measurements
Fair Value of Measurements	5. Fair Value of Measurements Fair value hierarchy classifications of the financial instruments that are measured at fair value on a recurring basis are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 10,317 ​ $ 10,317 Warrant liabilities ​ — ​ — ​ 10,584 ​ 10,584 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033 ​ Valuation techniques and the inputs The table below presents valuation techniques and inputs used in the fair value measurement categorized within Level 3 of the fair value hierarchy (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation techniques Inputs March 31, 2024 December 31, 2023 Convertible promissory notes, current Discounted Cash Flow Model (“DCF”) Discount rate, risk-free rate, credit spread, contractual cash flows ​ $ 5,645 ​ $ — ​ ​ PWERM (“Probability-Weighted Expected Return Method”) ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 27,794 Convertible promissory notes, net of current Binomial Lattice Model (“BLM”) Stock price, volatility, remaining term, risk-free rate, credit spread ​ $ 4,672 ​ $ — ​ ​ PWERM ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 6,239 Warrant liabilities – private and public warrants Black Scholes Merton Model (“BSM”) or BLM Exercise price, term to expiration, volatility, risk-free rate ​ $ 9,150 ​ $ — Warrant liabilities - other ​ ​ ​ ​ $ 1,434 $ — ​ As of March 31, 2024, the key inputs for the convertible promissory notes, current using the DCF were as follows: remaining term of 0.25 years and a discount rate of 10.2%. As of March 31, 2024, the key inputs for the convertible promissory notes, net of current using the BLM were as follows: stock price of $6.58, volatility of 32.2%, remaining term of 1.9 years, risk-free rate of 4.6%, and credit spread of 5.0%. As of March 31, 2024, the key inputs for the private placement warrants using the BSM were as follows: exercise price of $11.50 per share, term to expiration of 5 years, volatility range of 19.4% and a risk-free rate of 4.2%. As of March 31, 2024, the key inputs for the public warrants using the BLM were as follows: exercise price of $11.50 per share and term to expiration of 5.0 years. As of March 31, 2024, the key inputs for the warrant liabilities – other using the BSM were as follows: an exercise price of $5.00 per share, or $10.00 per share or $18.75 per share, term to expiration ranging from 0.4 years to 2.6 years, volatility ranging from 29.5% to 32.7%, and a risk-free rate ranging from 4.4% to 5.4%. As of December 31, 2023, the PWERM was used as Legacy GCT was a private company. After the Closing, and as of March 31, 2024, the valuation techniques used reflect that the Business Combination was consummated. The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Convertible promissory notes fair value - beginning of period ​ $ 34,033 ​ $ 31,166 Change in fair value of convertible promissory notes ​ 1,203 ​ (549) Conversion of convertible promissory notes ​ (41,209) ​ — Borrowing of convertible promissory notes ​ 16,290 ​ — Convertible promissory notes fair value - end of period ​ $ 10,317 ​ $ 30,617 ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Warrant Liabilities Fair value - beginning of period ​ $ — ​ $ — Private and public warrants assumed at Closing ​ 5,958 ​ — Change in fair value of warrant liabilities ​ 4,626 ​ — Warrant Liabilities Fair value - end of period ​ $ 10,584 ​ $ — ​ The gains and losses from fair value re-measurement of Level 3 financial liabilities are recorded as other income, net in the condensed consolidated statements of operations.	2. Fair Value of Measurements Fair Value Hierarchy Recurring fair value measurements Fair value hierarchy classifications of the financial instruments that are measured at fair value on a recurring basis as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2023 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033 ​ Recurring fair value measurements, continued ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2022 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 31,166 ​ $ 31,166 ​ Valuation techniques and the inputs The table below presents valuation techniques and inputs used in the fair value measurement categorized within Level 3 of the fair value hierarchy as of December 31, 2023 and 2022. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Valuation techniques Inputs 2023 2022 Convertible promissory notes, current PWERM Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ 27,794 ​ $ 31,166 Convertible promissory notes, net of current ​ ​ ​ 6,239 ​ — ​ The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities for the years ended December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Fair value as of beginning of period ​ $ 31,166 ​ $ 56,996 Change in fair value of convertible promissory notes ​ 1,428 ​ 450 Conversion of convertible promissory notes ​ (61) ​ (33,140) Repayment of convertible promissory notes ​ (500) ​ (1,140) Transfer of convertible promissory notes to bank borrowings ​ — ​ (1,000) Borrowing of convertible promissory notes ​ 2,000 ​ 9,000 Fair value as of end of period ​ $ 34,033 ​ $ 31,166 ​ The gains and losses from fair value re-measurement of Level 3 financial liabilities are recorded as other income (expense), net in the consolidated statements of operations.

Balance Sheet Components_2

Balance Sheet Components	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Balance Sheet Components
Balance Sheet Components	6. Balance Sheet Components Inventory Inventories consists of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Raw materials ​ $ 414 ​ $ 448 Work-in-process ​ 498 ​ 601 Finished goods ​ 872 ​ 437 Total inventory ​ $ 1,784 ​ $ 1,486 ​ There were no write-downs of inventory into cost of net revenues for the three months ended March 31, 2024 and 2023. Prepaid expenses and other assets Prepaid expenses and other assets consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Prepaid expenses ​ $ 3,345 ​ $ 433 Prepaid inventory ​ ​ 1,429 ​ ​ 279 Lease deposit ​ 413 ​ 434 Other receivables and current assets ​ 279 ​ 117 IPO expenses ​ — ​ 1,643 Prepaid expenses and other current assets ​ $ 5,466 ​ $ 2,906 ​ Accrued and other current liabilities Accrued and other current liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Payroll and related expenses ​ $ 9,830 ​ $ 9,880 Accrued payables ​ ​ 7,853 ​ ​ 6,319 Other taxes payable ​ ​ 3,399 ​ ​ 158 Current portion of interest payable ​ ​ 3,395 ​ ​ 6,915 Professional fees ​ 444 ​ 499 Royalty and license fee ​ 60 ​ 58 Product warranty ​ 64 ​ 55 Other ​ 107 ​ 72 Accrued and other current liabilities ​ $ 25,152 ​ $ 23,956 ​	3. Balance Sheet Components Inventory Inventory as of December 31, 2023 and 2022 consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Raw materials ​ $ 448 ​ $ 182 Work-in-process ​ 601 ​ 891 Finished goods ​ 437 ​ 2,407 ​ ​ $ 1,486 ​ $ 3,480 ​ Prepaid expenses and other assets Prepaid expenses and other assets as of December 31, 2023 and 2022 consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 IPO expenses ​ $ 1,643 ​ $ — Intellectual property rights ​ 761 ​ 861 Lease deposit ​ 554 ​ 555 Prepaid expenses ​ 433 ​ 799 Prepaid inventory ​ 279 ​ 1,310 Other receivables ​ 105 ​ 102 Costs incurred to fulfill a contract ​ 12 ​ 39 ​ ​ 3,787 ​ 3,666 Less: Non-current assets ​ (881) ​ (993) Prepaid expenses and other current assets ​ $ 2,906 ​ $ 2,673 ​ Property and equipment, net Property and equipment, net as of December 31, 2023 and 2022 consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Production equipment ​ $ 14,887 ​ $ 14,800 IT equipment ​ 1,127 ​ 1,212 Furniture and fixtures ​ 784 ​ 799 Leasehold improvements ​ 293 ​ 388 Fixed assets in process ​ — ​ 39 Total property and equipment ​ 17,091 ​ 17,238 Less: accumulated depreciation and amortization ​ (16,319) ​ (16,127) ​ ​ $ 772 ​ $ 1,111 ​ Depreciation expense was approximately $640,000 and $518,000 for the years ended December 31, 2023 and 2022, respectively. ​ 3. Balance Sheet Components Leases The Company is obligated under finance leases covering certain IT equipment that expire at various dates during the next year. The Company also has several noncancellable operating leases, primarily for office equipment and office space that expire over the next four years. The office space leases generally contain renewal options for periods ranging from two Payments due under the lease contracts include fixed payments plus, for many of the Company’s leases, variable payments. For office space leases, variable payments include payments for the Company’s proportionate share of the building’s property taxes, insurance, and common area maintenance. For office equipment leases for which the Company has elected not to separate lease and non-lease components, maintenance services are provided by the lessor at a fixed cost and are included in the fixed lease payments for the single, combined lease component. The Company also elected to discount its office equipment lease liabilities using a risk-free rate. The components of lease expense for the years ended December 31, 2023 and 2022 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Operating lease expense ​ $ 772 ​ $ 733 Finance lease expense ​ ​ Amortization of right of use assets ​ 14 ​ 18 Interest on lease liabilities ​ 1 ​ 2 Total finance lease expense ​ 15 ​ 20 ​ ​ $ 787 ​ $ 753 ​ Other information related to leases for the years ended December 31, 2023 and 2022 was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Supplemental cash flow information: ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ Cash used in operations for operating leases ​ $ 766 ​ $ 770 ​ Cash used in operations for finance leases ​ 1 ​ 2 ​ Payments made on finance leases ​ 17 ​ 24 ​ ROU assets obtained in exchange for lease obligations: ​ ​ ​ Operating leases ​ 1,476 ​ 826 ​ Weighted average remaining lease term: ​ ​ ​ Operating leases ​ 2.25 years ​ 3.57 years ​ Finance leases ​ — ​ 0.90 years ​ Weighted average discount rate: ​ ​ ​ Operating leases ​ 4.66 % 4.00 % Finance leases ​ — ​ 9.70 % ​ ​ 3. Balance Sheet Components Leases Amounts disclosed for ROU assets obtained in exchange for lease obligations include amounts added to the carrying amount of ROU assets resulting from lease modifications and reassessments. Maturities of lease liabilities under noncancellable leases as of December 31, 2023 are as follows: ​ ​ ​ ​ ​ ​ Operating (in thousands) ​ leases 2024 ​ $ 743 2025 ​ 712 2026 ​ 169 Total undiscounted lease payments ​ 1,624 Less: imputed interest ​ (94) Total lease liabilities ​ $ 1,530 ​ Intangibles, net Intangibles, net as of December 31, 2023 and 2022 consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Intellectual properties ​ $ 1,118 ​ $ 943 Intangible assets in process ​ — ​ 180 Total acquired intangibles ​ 1,118 ​ 1,123 Less: accumulated amortization ​ (873) ​ (451) ​ ​ $ 245 ​ $ 672 ​ Amortization expense was approximately $422,000 and $147,000 for the years ended December 31, 2023 and 2022, respectively. Accrued and other current liabilities Accrued and other current liabilities as of December 31, 2023 and 2022 consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Payroll and related expenses ​ $ 10,038 ​ $ 6,635 Accrued payables ​ 6,319 ​ 2,233 Royalty and license fee ​ 58 ​ 37 Professional fees ​ 499 ​ 479 Current portion of interest payable ​ 6,915 ​ 2,944 Product warranty ​ 55 ​ 64 Other ​ 72 ​ 104 ​ ​ $ 23,956 ​ $ 12,496 ​ ​ 3. Balance Sheet Components Other liabilities Other liabilities as of December 31, 2023 and 2022 consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Severance payments liability ​ $ 92 $ 76 Interest payable ​ 16 — ​ ​ $ 108 $ 76 ​

Debt_2

Debt	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Debt
Debt	7. Debt The Company’s outstanding debt was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 ​ ​ Principal ​ Fair Value ​ Principal ​ Fair Value Convertible promissory notes: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Historical convertible promissory notes ​ $ 5,630 ​ $ 5,645 ​ $ 35,347 ​ $ 34,033 2023 & 2024 convertible promissory notes ​ 5,000 ​ 4,672 ​ — ​ — Borrowings: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ KEB Hana Bank ​ 6,682 ​ 6,682 ​ 6,980 ​ 6,980 IBK Industrial Bank ​ 6,831 ​ 6,831 ​ 7,135 ​ 7,135 Note payable (one individual investor) ​ 1,000 ​ 1,000 ​ 1,000 ​ 1,000 M-Venture Investment, Inc. ​ 7,425 ​ 7,425 ​ 7,756 ​ 7,756 Anapass, Inc, related party ​ 9,653 ​ 9,653 ​ 10,082 ​ 10,082 i Best Investment Co., Ltd ​ 7,425 ​ 7,425 ​ 10,082 ​ 10,082 Kyeongho Lee, related party ​ 824 ​ 824 ​ 1,474 ​ 1,474 Total debt ​ $ 50,470 ​ 50,157 ​ $ 79,856 ​ 78,542 Less: current portion ​ ​ ​ ​ (45,485) ​ ​ ​ ​ (72,303) Debt, net of current portion ​ ​ ​ ​ $ 4,672 ​ ​ ​ ​ $ 6,239 ​ The Company elected the fair value option for the 2023 & 2024 convertible promissory notes and the historical convertible promissory notes (see Note 5). The Company’s other borrowings approximate their fair value because interest rates are at prevailing market rates and/or the short-term nature of the remaining obligations. See Note 14 for additional information on related parties. Expected future minimum principal payments under the Company’s total debt is as follows as of March 31, 2024 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible ​ ​ ​ ​ ​ ​ Notes ​ ​ ​ ​ ​ ​ Years ​ Payable ​ Borrowing ​ Total 2024, remainder ​ $ 5,630 ​ $ 39,840 ​ $ 45,470 2025 ​ — ​ — ​ — 2026 ​ 5,000 ​ — ​ 5,000 Total debt ​ $ 10,630 ​ $ 39,840 ​ $ 50,470 ​ Convertible Promissory Notes Historical Convertible Promissory Notes Between 2017 and 2022, the Company issued convertible promissory notes to various investors with maturity dates ranging from October 2020 to April 2025. The annual interest rates varied between 4.0% and 7.0%. In November 2023, the Company entered into an amendment with certain convertible promissory noteholders to modify the conversion terms such that these notes were automatically convertible upon a special purpose acquisition company (“SPAC”) transaction. In March 2024, upon the Closing of the Business Combination, an aggregate principal and interest amount of $32.1 million converted into 4,258,223 shares of common stock at a conversion price of $10.00. As of March 31, 2024, the remaining principal and interest amount of $7.9 million was outstanding and related to two noteholders where conversion is at each noteholder’s discretion and at a conversion price of $3.50 per share. In April 2024, the Company repaid one of the convertible promissory notes (see Note 17). 2023 & 2024 Convertible Promissory Notes In November 2023, February 2024 and March 2024, the Company issued convertible promissory notes to certain investors (the “CVT Investors”), pursuant to which the CVT Investors agreed to lend to the Company an aggregate principal amount of $13.3 million. These notes had maturity dates ranging from November 2026 to March 2027, bore an interest rate of 5.0% and were automatically convertible upon IPO or SPAC transaction. In March 2024, upon the Closing of the Business Combination, an aggregate principal and interest amount of $13.4 million converted into 2,004,535 shares of common stock at a conversion price of $6.67. As of March 31, 2024, none of the notes issued to CVT Investors remain outstanding. In February 2024, the Company issued a convertible promissory note to a strategic investor for a principal amount of $5.0 million, which matures in February 2026 and bears an interest rate of 5.0% per annum. On or after the earlier of (i) six months from the issuance date of the convertible promissory note and (ii) the Closing of the Business Combination, the noteholder may demand that the Company convert all principal and interest due under the convertible promissory note into shares of Company’s common stock, at a conversion price of $10.00 per share. This note includes customary representations, warranties, and events of default, as well as a covenant relating to the performance of obligations by the Company related to the Company’s 5G activity. As of March 31, 2024, the remaining principal and interest amount of $5.0 million was outstanding. Borrowings Pursuant to Term Loan and Security Agreements KEB Hana Bank In July 2016, the Company entered into an unsecured term loan agreement with KEB Hana Bank pursuant to which it borrowed KRW 9.0 billion ($6.7 million), bearing a variable interest rate (2.6% initial annual interest rate and 5.2% as of March 31, 2024), paid monthly, and maturing in July 2017. The terms of such unsecured term loan agreement have been extended annually for additional one-year terms since 2017, and the maturity date is July 2024. Anapass, Inc., a related party, provided certificates of deposit as collateral to KEB Hana Bank to secure the Company’s obligations under this loan (see Note 8). As of March 31, 2024, the remaining principal and interest amount of $6.7 million was outstanding. IBK Industrial Bank In January 2017, the Company entered into a term loan agreement with IBK Industrial Bank pursuant to which the Company borrowed KRW 9.2 billion ($6.8 million). The term loan has a maturity date in November 2024 and bears an annual interest rate of 4.9%. As of March 31, 2024, the remaining principal and interest amount of $6.8 million was outstanding. Note Payable (One Individual Investor) In June 2021, the Company entered into a note payable agreement with an individual investor pursuant to which the Company borrowed $1.0 million. The note has a maturity date in June 2024 and bears an annual interest rate of 4.0%. In April 2022, the Company entered into an amendment with this one individual investor to remove the conversion right from the note payable. As of March 31, 2024, the remaining principal and interest amount of $1.1 million was outstanding. M-Venture Investment, Inc. In October 2021, the Company entered into a term loan and security agreement with M-Venture Investment, Inc. pursuant to which the Company borrowed KRW 5.0 billion ($3.7 million) and repaid KRW 0.6 billion ($0.4 million) and KRW 0.4 billion ($0.3 million) in 2021 and 2022, respectively, such that KRW 4.0 billion ($3.0 million) remained outstanding. The term loan has a maturity date in October 2024 and bears an annual interest rate of 6.5%. As of March 31, 2024, the remaining principal and interest amount of $3.1 million was outstanding. In April 2022, the Company entered into a term loan and security agreement with M-Venture Investment, Inc. pursuant to which the Company borrowed amounts in two draws of KRW 1.0 billion ($0.7 million) and KRW 5.0 billon ($3.7 million), respectively. The term loan has a maturity date in April 2024 and each respective draw bears an annual interest rate of 6.5% and 8.7%. As of March 31, 2024, the remaining principal and interest amount of $4.8 million was outstanding. In April 2024, the Company executed amendments with M-Venture Investment, Inc. (see Note 17). Anapass, Inc., Related Party In July 2016, the Company entered into a loan agreement with Anapass, Inc. pursuant to which the Company borrowed KRW 6.0 billion ($4.5 million) in a term loan. Interest only payments are due monthly at 5.5% per annum and the principal amount of the term loan is due on the maturity date of July 2024. The loan is collateralized by the Company’s assets as described under the Assets Pledged as Collateral (see Note 8). As of March 31, 2024, the remaining principal and interest amount of $4.5 million was outstanding. In May and September 2022, the Company entered into two term loan agreements with Anapass, Inc. pursuant to which the Company borrowed KRW 3.0 billion ($2.2 million) and KRW 4.0 billion ($3.0 million) in term loans. The term loans have respective maturity dates in May 2024 and September 2024 and both bear an annual interest rate of 5.5%. As of March 31, 2024, the remaining principal and interest amount of $5.2 million was outstanding. i Best Investment Co., Ltd From 2022 and 2023, the Company entered into multiple term loans and security agreements with i Best Investment Co., Ltd pursuant to which it borrowed principal amounts in six draws with an aggregate principal balance of KRW 14.0 billion ($10.3 million). All of the term loans have a maturity date in June 2024 and bear an annual interest rate of 6.5%. In December 2023, the Company made a $0.8 million repayment of the outstanding principal and interest on its second draw. In March 2024, the Company made a $2.3 million repayment of the outstanding principal and interest amount of its fourth draw. As of March 31, 2024, the remaining principal and interest amounts outstanding were as follows: $3.3 million outstanding on its first draw, $1.6 million outstanding on its third draw, $2.3 million outstanding on its fifth draw and $0.8 million on its sixth draw. Kyeongho Lee, Related Party From 2017 and 2021, the Company entered into multiple promissory note and term loan agreements with Kyeongho Lee pursuant to which the Company borrowed (a) KRW 500.0 million ($0.4 million), and KRW 500.0 million ($0.4 million) in promissory notes, and (b) KRW 1.0 billion ($0.7 million) and KRW 110.0 million ($0.1 million) in term loans. The promissory notes have a maturity date in November 2024 and bear an annual interest rate varying from 7.5% and 9.0%. During the three months ended March 31, 2024, the Company repaid in full one of the term loans. The term loan has a maturity date in May 2024 and bears an annual interest rate of 0.0%. As of March 31, 2024, the remaining principal and interest amount of $0.7 million and $82,000 was outstanding as it related to the promissory notes and a term loan, respectively.	4. Debt Borrowings ​ ​ ​ ​ ​ ​ ​ ​ ​ Category Creditor Maturity date Annual interest rate Korean Won KEB Hana Bank (*1) 7/12/2024 5.23 % Korean Won IBK Industrial Bank (*1) 11/20/2024 4.89 % Korean Won Anapass, Inc. 7/25/2024 5.50 % Korean Won Anapass, Inc. 5/10/2024 5.50 % Korean Won Anapass, Inc. 9/15/2024 5.50 % Korean Won Kyeongho Lee 11/19/2024 9.00 % Korean Won Kyeongho Lee 5/27/2024 0 % Korean Won Kyeongho Lee 11/24/2023 6.80 % Korean Won Kyeongho Lee 11/30/2024 7.50 % Korean Won Kyeongho Lee 12/2/2024 (*9) 7.50 % Korean Won M-Venture Investment, Inc. (*3) 10/29/2024 6.50 % Korean Won M-Venture Investment, Inc. (*4) 4/26/2024 6.50% - 8.65 %(*6) Korean Won i Best Investment Co., Ltd. (*5) 3/14/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. (*7) 12/22/2023 6.50 % Korean Won i Best Investment Co., Ltd. 3/12/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. 1/12/2024 (*9) 6.50 % Korean Won i Best Investment Co., Ltd. 3/14/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. 1/26/2024 (*2) 6.50 % Promissory Note One (1) individual investor 6/30/2024 4.00 % (*1) The limits for borrowings from KEB Hana Bank and IBK Industrial Bank are $6,980,000 and $7,135,000, respectively, and the bank deposit of Anapass, Inc., a related party, is pledged as collateral for borrowings from KEB Hana Bank and IBK Industrial Bank (see Notes 5 and 12). As of the current fiscal year end, collateral was provided to Anapass, Inc. in relation to the borrowings from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. (see Notes 5 and 12). (*2) Maturity date was extended for five ​ 4. Debt Borrowings (*3) (*4) (*5) (*6) (*7) (*8) three (*9) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ Category ​ Creditor ​ December 31, 2023 ​ December 31, 2022 Korean Won KEB Hana Bank (*1) ​ $ 6,980 ​ $ 7,102 Korean Won IBK Industrial Bank (*1) ​ 7,135 ​ 7,260 Korean Won Anapass, Inc. ​ 4,653 ​ 4,735 Korean Won Anapass, Inc. ​ 2,327 ​ 2,367 Korean Won Anapass, Inc. ​ 3,102 ​ 3,156 Korean Won Kyeongho Lee ​ 388 ​ 395 Korean Won Kyeongho Lee ​ 85 ​ 87 Korean Won Kyeongho Lee ​ — ​ 24 Korean Won Kyeongho Lee ​ 388 ​ 395 Korean Won Kyeongho Lee ​ 613 ​ 789 Korean Won M-Venture Investment, Inc. (*3) ​ 3,102 ​ 3,156 Korean Won M-Venture Investment, Inc.(*4) ​ 4,653 ​ 4,734 Korean Won i Best Investment Co., Ltd. (*5) ​ 3,102 ​ 3,156 Korean Won i Best Investment Co., Ltd. (*7) ​ — ​ — Korean Won i Best Investment Co., Ltd. ​ 1,551 ​ — Korean Won i Best Investment Co., Ltd. ​ 2,327 ​ — Korean Won i Best Investment Co., Ltd. ​ 2,327 ​ — Korean Won i Best Investment Co., Ltd. ​ 776 ​ — Promissory Note One (1) individual investor ​ 1,000 ​ 1,000 Bank Borrowings ​ $ 44,509 ​ $ 38,356 ​ Maturities of borrowings as of December 31, 2023 were as follows: ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2024 ​ $ 44,509 Total ​ $ 44,509 ​ ​ 4. Debt Convertible Notes Details of convertible notes are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Category ​ Creditor ​ December 31, 2023 ​ December 31, 2022 Current convertible notes (*1) ​ ​ 1st SG Ace Inc. (*2) ​ $ 7,620 ​ $ 8,461 2nd M-Venture Investment, Inc. and one (1) institution (*3) ​ 7,620 ​ 8,461 7th NA Korea Trans Fund No.4, one (1) institution and eight(8) individual investors (*4) ​ 2,198 ​ 1,932 16th NA Korea Trans Fund No.4 and two (2) individual investors ​ 387 ​ 330 22nd i Best Investment Co., Ltd. ​ 3,233 ​ 2,746 23rd Jeju Semiconductor Corp. ​ 908 ​ 771 24th One (1) individual investor ​ 665 ​ 565 25th M-Venture Investment Inc. (*5) ​ — ​ 3,511 26th Access Bio, Inc. ​ 5,163 ​ 4,389 ​ Subtotal ​ 27,794 ​ 31,166 Non-current convertible notes ​ ​ 25th M-Venture Investment Inc. (*5) ​ 3,614 ​ — 27th Blacktree Co., Ltd. ​ 2,625 ​ — ​ Subtotal ​ 6,239 ​ — ​ Total ​ $ 34,033 ​ $ 31,166 (*1) (*2) (*3) (*4) (*5) During the year ended December 31, 2022, GNI Partners Co., Ltd. exercised their conversion right of the convertible note of $708,000, thereby 202,168 common shares were issued. ​ 4. Debt Convertible Notes, During the year ended December 31, 2022, the right to early redemption was exercised for 8th convertible notes of $740,000, 9th convertible notes of $100,000 and 12th convertible notes of $340,000 issued to seven (7) individual investors and redemption was made in full during 2022. During the year ended December 31, 2022, the amendment to the 21st convertible note of $1 million issued to one (1) individual investor was made and conversion right was eliminated. The note with the right to claim early redemption was reclassed to short-term borrowings. During the year ended December 31, 2022, convertible notes of $32.5 million and unpaid interest of $2.6 million were converted into common shares due to the submission of listing eligibility review application to Korea Exchange, and common shares of 10,026,354 were issued. Maturities of convertible notes as of December 31, 2023, were as follows: ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2024 ​ $ 27,794 December 31, 2025 ​ 3,614 December 31, 2026 ​ 2,625 Total ​ $ 34,033 ​ Key terms for issuance of convertible notes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1st 2nd 7th 16th 22nd 23rd 24th 25th 26th 27th Issue Year ​ 2017 2017 2019 2020 2021 2021 2021 2022 2022 ​ 2023 Early repayment ​ (*1) (*1) (*2) (*1) (*1) (*1) (*1) (*2) (*3) ​ (*1) Repayment at maturity ​ The payment shall be made three years after the date of issue at an annual interest rate of 4% . The payment shall be made three years after the date of issue at an annual interest rate of 7% . The payment shall be made three years after the date of issue at an annual interest rate of 5% . The payment shall be made three years after the date of issue at an annual interest rate of 4% . ​ The payment shall be made three years after the date of issue at an annual interest rate of 5% . Rates applied at the repayment date ​ Upon repayment, there is a clause to reimburse the U.S. Dollar amount converted at the Won-Dollar exchange rate on the redemption date based on the Won amount converted at the Won-Dollar exchange rate at the date of issue. ​ N/A N/A N/A N/A N/A N/A ​ N/A Conversion price ​ $ 3.50 per share (*4) ​ ​ $ 6.67 per share ​ ​ 4. Debt, Convertible Notes, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1st 2nd 7th 16th 22nd 23rd 24th 25th 26th 27th Conversion - The holder of convertible notes can covert it at any time. ​ - If the Company issues a new equity instrument after issuing convertible notes, the holder of convertible notes may participate in conversion with the issuance price of the new equity instruments (1st, 2nd and 27th convertible notes) or $3.50 per share up to seven days prior to the issuance of the equity instruments. ​ - Conversion upon demand at holder’s discretion with conversion price equal to $3.50 ($6.67 for 27th convertible note) per share after issue date. ​ - Automatic conversion in an initial public offering (“IPO”) or business combination with SPAC (except for 1st and 24th convertible notes) (conversion price is adjusted to IPO price or SPAC conversion price). ​ - If the price at the time of issuance of a new equity instrument or the IPO is lower than $3.50, the conversion price of the convertible note is adjusted (except for 27th convertible note). ​ - Conversion price is adjusted every three months for one year after an IPO at KOSDAQ (However, adjusted price cannot be lower than 70% of $3.50 per share and cannot be higher than $3.50 per share) (7th convertible note). Number of convertible shares (*5) 5,142,858 shares ​ 553,790 shares 102,597 shares 874,286 shares 245,714 shares 180,000 shares 1,000,000 shares 1,428,571 shares 299,850 shares Collateral and guarantee (*6) ​ (*7) N/A (*8) N/A (*7) N/A (*7) N/A (*1) early repayment exercised once every quarter times in total for periods after from date issue convertible notes until from the date issue convertible notes (*2) times periods convertible convertible (*3) (*4) (*5) (*6) shares (*7) (*8) The convertible notes of the Company are designated as financial liabilities measured at fair value through profit or loss in accordance with ASC 840. Changes in fair value that occurred during the current period amounting to a gain of $2,619,000 (prior period: $2,673,000) and a loss of $4,047,000 (prior period: $3,123,000) were recognized as other income (expense), net on the consolidated statement of operations, respectively. In the year 2021, Amber International Ltd. acquired the 5th convertible note of $708,000, which was redeemed on behalf of the Company, in same conditions, and later the note was transferred to GNI Partners Co., Ltd. During the year 2022, GNI Partners Co., Ltd. exercised conversion rights and the note was converted to common shares in full. The 3rd convertible note issued to Shinsojae Energy Holdings Limited was transferred to NJ Holdings Inc. in June 2021. NJ Holdings Inc. exercised its conversion right during 2022, and as a result the 3rd convertible note was converted to common shares in full.

Commitments and Contingencies_3

Commitments and Contingencies	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies.
Commitments and Contingencies	8. Commitments and Contingencies Litigation The Company is subject to various claims arising in the ordinary course of business. Although no assurance can be given, the Company believes that it is not a party to any litigation of which the outcome, if determined adversely, would individually, or in the aggregate, be reasonably expected to have a material adverse effect on the business, consolidated operating results, cash flows or financial position of the Company as of March 31, 2024. Third parties have from time to time claimed, and others may claim in the future, that the Company has infringed their past, current or future intellectual property rights. These claims, whether meritorious or not, could be time consuming, result in costly litigation, require expensive changes in the Company’s methods of doing business or could require the Company to enter into costly royalty or licensing agreements, if available. As a result, these claims could harm the Company’s business, consolidated operating results, cash flows, and financial position. Purchase Commitment The Company has certain commitments for outstanding purchase orders related to the manufacture of certain wafers utilized by the Company and other services that, once the wafers are placed into production, are noncancelable. Otherwise, these production agreements are cancellable at any time with the Company required to pay all costs incurred through the cancellation date. However, the Company has rarely cancelled these agreements once production has started. As of March 31, 2024, the Company had no outstanding noncancelable purchase commitments for these production agreements. In July 2020, the Company entered into a research and development agreement with Samsung Electronics Co., Ltd (“Samsung”). According to the agreement, the Company would design 5G chip products and Samsung would provide development and intellectual property support, mass production set up support including mask sets for manufacturing and engineering sample chip supply to the Company for a specific product. The total fee amount for the research and development (“R&D”) services pursuant to the agreement was $21.1 million. The Company bore the risk of R&D failure and was obligated to pay the $21.1 million total fee based on milestones defined in the agreement, of which $11.7 million was due based on development milestones and $9.4 million of additional NRE (“non-recurring engineering”) was to be paid within a maximum of 4 years In February 2024, the Company and Alpha Holdings Co., Ltd. (“Alpha”) entered into a foundry product development agreement related to 5G chip development for a total fee of $7.6 million. The Company bears the risk of R&D failure and is obligated to pay the fee based on milestones defined in the agreement. The Company recognizes R&D expenses based on an estimate of the percentage completion of services provided by Alpha during the respective financial reporting period. For the three months ended March 31, 2024, the Company recorded $3.5 million in R&D expenses related to services provided by Alpha. The aggregate unpaid amount related to this agreement is $5.0 million as of March 31, 2024. Assets Pledged as Collateral The Company has provided collateral to Anapass, Inc., a related party (see Note 14), for borrowings from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. in the amount of $6.7 million, $6.8 million and $9.7 million, respectively, as of March 31, 2024, and $7.0 million, $7.1 million and $10.1 million, respectively, as of December 31, 2023 (see Note 7). The following table includes a summary of the collateral provided to Anapass, Inc. (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, Secured ​ ​ 2024 ​ 2023 ​ Creditor Cash and cash equivalents ​ $ 16,122 ​ $ 254 ​ ​ Accounts receivable ​ ​ 5,118 ​ ​ 4,920 ​ Inventory ​ 1,784 ​ 1,486 Anapass, Inc. Property and equipment ​ 1,988 ​ 352 Intangible assets and others ​ 187 ​ 199 ​	5. Commitments and Contingencies ​ Litigation The Company is subject to various claims arising in the ordinary course of business. Although no assurance can be given, the Company believes that it is not presently a party to any litigation of which the outcome, if determined adversely, would individually, or in the aggregate, be reasonably expected to have a material adverse effect on the business, consolidated operating results, cash flows or financial position of the Company. Third parties have from time to time claimed, and others may claim in the future, that the Company has infringed their past, current or future intellectual property rights. These claims, whether meritorious or not, could be time consuming, result in costly litigation, require expensive changes in the Company’s methods of doing business or could require the Company to enter into costly royalty or licensing agreements, if available. As a result, these claims could harm the Company’s business, consolidated operating results, cash flows and financial position. Purchase Commitment The Company has certain commitments for outstanding purchase orders related to the manufacture of certain wafers utilized by the Company and other services that, once the wafers are placed into production, are noncancelable. Otherwise, these production agreements are cancellable at any time with the Company required to pay all costs incurred through the cancellation date. However, the Company has rarely cancelled these agreements once production has started. As of December 31, 2023 and 2022, the Company had outstanding noncancelable purchase commitments for these production agreements of $0 and $0.5 million, respectively. The Company entered into a research and development agreement with Samsung Electronics Co., Ltd (“Samsung”) in July 2020. According to the agreement, the Company designs 5G chip products and Samsung provides development and intellectual property support, mass production set up support including mask sets for manufacturing and engineering sample chip supply to the Company. Total fee amount of the agreement is $21.1 million composed of $11.7 million to be paid over development milestones and $9.4 million of additional NRE (non-recurring engineering) to be paid within maximum 4 years after planned product first shipment date. The Company bears the risk of R&D failure and is obligated to pay the fees based on milestones defined in the agreement. Pursuant to ASC 730-20, Research and Development, the Company expensed $0.4 million and $7.1 million related to this agreement for the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023 and 2022, $15.8 million and $15.4 million, respectively, of unpaid recorded expenses were included in accounts payable on the consolidated balance sheets. The aggregated unpaid amount on this agreement is $17.1 million as of December 31, 2023. Assets Pledged as Collateral The Company has provided collateral to Anapass, Inc., a related party, for borrowings of GCT R&D, a subsidiary of GCT, from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. in the amount of $7.0 million, $7.1 million and $10.1 million, respectively, as of December 31, 2023, and $7.1 million, $7.3 million and $10.3 million, respectively, as of December 31, 2022 (see Note 4). 5. Commitments and Contingencies, Assets Pledged as Collateral, Details of collateral provided to Anapass, Inc. are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) December 31, December 31, Secured ​ ​ 2023 ​ 2022 ​ Creditor Cash and cash equivalents ​ $ 254 ​ $ 1,363 Accounts receivable ​ 4,920 ​ 4,453 Inventory ​ 1,486 ​ 3,480 Anapass, Inc. Property and equipment ​ 352 ​ 485 Intangible assets and others ​ 199 ​ 531 ​

Common Stock_2

Common Stock	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Common Stock
Common Stock	9. Common Stock In connection with the Closing of the Business Combination, the Company increased its total number of authorized shares to 440,000,000 shares, consisting of 400,000,000 shares of common stock and 40,000,000 shares of preferred stock. The Company has reserved shares of common stock for issuance as follows (in thousands): ​ ​ ​ ​ ​ ​ March 31 December 31 ​ ​ 2024 ​ 2023 Warrants ​ 26,724 ​ 2,894 Shares available for future grant from 2024 plan ​ 3,983 ​ — Convertible promissory notes 800 1,835 Options issued and outstanding 668 668 Shares available for future grant from 2024 ESPP 600 — RSUs outstanding 392 392 Shares available for future grant from 2011 plan — 113 Total 33,167 5,902 ​	6. Common Stock The Company’s total number of authorized shares is 200,000,000 shares and the total number of common shares issued is 129,395,774 $0.001 The Company has reserved the following shares of authorized but unissued common stock as of December 31, 2023 ​ ​ ​ Options outstanding 3,579,294 RSUs outstanding 2,099,970 Shares available for grant from 2011 plan 605,826 Warrants 9,200,000 Convertible promissory notes 9,827,666 Total 25,312,756 ​

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2023
Redeemable Convertible Preferred Stock
Redeemable Convertible Preferred Stock	7. Redeemable Convertible Preferred Stock As the conditions for automatic conversion under the Certificate of Incorporation were satisfied by submitting an eligibility review application to the Korea Exchange during the prior fiscal year ended December 31, 2022, all outstanding shares of redeemable convertible preferred stock were converted to common stocks, except for cancellations related to unconfirmed shareholders, and the accumulated dividends for Series C redeemable convertible preferred stock and Series G redeemable convertible preferred stock were paid with 28,685,582 shares of common stock. According to Certificate of Incorporation filed on April 27, 2022, the shares of common stock issued upon such automatic conversion of redeemable convertible preferred stock shall automatically convert back into the applicable series of redeemable convertible preferred stock (“Preferred Stock Reversion”) if an IPO has not occurred within two The Company was accreting the carrying value of the Series C and Series G to the redemption values. The accretion amounts were determined using the effective interest rate method and dividend rights and amounted to zero and $2.2 million for the years ended December 31, 2023 and 2022, respectively, for Series G. Due to the modification to Series C, the carrying value of Series C is greater than the redemption value and, therefore, no further accretion has been recorded in the years ended December 31, 2023 and 2022. Upon amendment of the Certificate of Incorporation dated April 27, 2022, redemption rights were removed for all Series Preferred. As a result, all Series Preferred were changed to be not redeemable. Also upon automatic conversion under the Certificate of Incorporation during the current period, all Series Preferred were converted to common stock, and accretion has stopped.

Warrants_2

Warrants	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Warrants
Warrants	10. Warrants The following table represents a summary of warrants to purchase shares of the Company’s common stock that are outstanding (in thousands, except for exercise price): ​ ​ ​ ​ ​ ​ ​ Issue Date March 31, 2024 Exercise Price Expiration August 2021 ​ 299 ​ $ 10.00 - $18.75 ​ (1) September 2021 300 ​ $ 5.00 (1) February 2023 - June 2023 2,115 ​ $ 10.00 - $18.75 (1) July 2023 80 ​ $ 10.00 (1) October 2023 100 ​ $ 10.00 (1) Private and public warrants 23,830 ​ $ 11.50 ​ March 26, 2029 Tota l 26,724 ​ ​ (1) Within 3 years from the date of issuance. See Note 3 with respect to further details on the private and public warrants and Note 5 with respect to valuation techniques and assumptions because the warrants are all liability-classified and subject to fair value measurement each reporting period.	8. Warrants Stock Warrants The Company has issued stock purchase warrants (the “Warrants”). The Warrants entitle the holder to purchase a specified number of shares of the Company’s common stock or new series of preferred stock at a specified price. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Issued Exercised Expired/ Outstanding ​ ​ ​ ​ ​ ​ Cancelled ​ ​ December 2020 (*1) 2,514,285 — (2,514,285) — February 2021 (*2) 342,857 — (342,857) — August 2021 (*3) 999,997 — — 999,997 September 2021 (*3) 428,571 — — 428,571 February 2023 ~ June 2023 (*7) (*9) 7,685,717 (428,572) — 7,257,145 July 2023 (*7) 228,572 — — 228,572 October 2023 (*7) 285,715 — — 285,715 ​ ​ ​ ​ ​ ​ ​ ​ ​ Exercise Price Expiration December 2020 (*1) ​ $ 3.50 (*5) Earlier of within 2 years from the date of issuance or 2 weeks before U.S. IPO or Korea IPO February 2021 (*2) ​ $ 3.50 (*4) Within 18 months from the date of issuance August 2021 (*3) ​ $ 3.50 (*6) Within 3 years from the date of issuance September 2021 (*3) ​ $ 3.50 (*5) Within 3 years from the date of issuance February 2023 ~ June 2023 (*7) (*9) ​ $ 3.50 (*8) Within 3 years from the date of issuance July 2023 (*7) ​ $ 3.50 (*10) Within 3 years from the date of issuance October 2023 (*7) ​ $ 3.50 (*10) Within 3 years from the date of issuance (*1) (*2) (*3) (*4) (*5) (*6) (*7) (*8) (*9) (*10) During the year ended December 31, 2023, warrants were exercised for 428,572 common shares. The number of warrants outstanding as of December 31, 2023 were 9,200,000 shares.

Stock-Based Compensation_2

Stock-Based Compensation	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Stock-Based Compensation
Stock-Based Compensation	11. Stock-Based Compensation 2011 Incentive Compensation Plan Legacy GCT’s 2011 Incentive Compensation Plan (the “2011 Plan”) permitted the grant of options, stock awards, and RSUs. In connection with the Closing of the Business Combination, the 2011 Plan was terminated, the remaining unallocated shares reserved under the 2011 Plan were cancelled and no new awards will be granted under the 2011 Plan. Each award of Legacy GCT stock options and RSUs were converted into equivalent Company stock options and RSUs with the same terms and conditions under the plan described below. 2024 Incentive Compensation Plan In connection with the Closing of the Business Combination, the Company adopted the 2024 Incentive Compensation Plan (the “2024 Plan”) under which 3,983,334 shares of common stock were initially reserved for issuance, subject to approval by the Company’s boards of directors. The 2024 Plan permits the grant of stock options, stock appreciation rights, stock awards, restricted stock units, dividend equivalent right, cash awards and other awards to employees, non-employee directors, non-employee members of the board of directors, or consultants or independent advisors. Stock options outstanding under the 2024 Plan were as follows (in thousands, except per share amounts and years): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Number of ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ Options ​ Average ​ Contractual Life ​ Aggregated ​ ​ Outstanding ​ Exercise Price ​ (in Years) ​ Intrinsic Value Balance as of December 31, 2023 ​ 3,579 ​ $ 0.02 ​ 5.5 ​ $ 4,405 Reverse recapitalization ​ (2,911) ​ ​ 0.09 ​ — ​ ​ — Balance as of December 31, 2023 (1) ​ 668 ​ ​ 0.11 ​ 5.5 ​ ​ 4,405 Granted ​ — ​ ​ — ​ — ​ ​ — Exercised ​ — ​ ​ — ​ — ​ ​ — Cancelled ​ — ​ ​ — ​ — ​ ​ — Balance as of March 31, 2024 668 $ 0.11 5.3 $ 5,543 Vested as of March 31, 2024 667 ​ $ 0.11 5.3 $ 5,532 Exercisable as of March 31, 2024 634 ​ $ 0.11 5.1 $ 5,256 (1) Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (see Note 3). There were no options granted during the three months ended March 31, 2024 and 2023. As of March 31, 2024, unrecognized compensation cost related to stock options was nominal. Founder Awards to Board of Directors In 2021, an aggregate of 90,000 founder shares of common stock were transferred to three members of Concord III’s board of directors. The shares contained both a performance condition based upon a liquidity event and a service vesting condition. As the liquidity and services conditions were met upon the Closing of the Business Combination, the Company recognized $0.9 million of stock-based compensation during the three months ended March 31, 2024. Restricted Stock Units In December 2023, various employees and directors of Legacy GCT were granted RSUs that contain both a performance condition based upon a liquidity event and a service vesting condition such that the RSUs vest in four equal annual installments from the grant date. Any unvested RSUs are forfeited upon separation from the Company. The liquidity condition was met upon the Closing of the Business Combination and the Company recognized $0.3 million of stock-based compensation. RSUs outstanding under the 2024 Plan were as follows (in thousands, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of RSUs ​ Average Grant ​ ​ Outstanding ​ Date Fair Value Balance as of December 31, 2023 ​ 2,100 ​ $ 1.15 Reverse recapitalization ​ (1,708) ​ ​ 5.01 Balances as of December 31, 2023 (1) ​ 392 ​ $ 6.16 Granted — ​ — Vested — ​ — Cancelled — ​ — Balance as of March 31, 2024 392 ​ $ 6.16 (1) Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (see Note 3). As of March 31, 2024, there was $2.1 million of unrecognized compensation cost related to RSUs, which is expected to be recognized on a straight-line basis over a weighted average period of 3.7 years.	9. Stock-Based Compensation In September 2011, the Board of Directors adopted the 2011 Incentive Compensation Plan (the “2011 Plan”). The Company reserved 6,277,777 shares of common stock for issuance under the 2011 Plan. Such share reserve is comprised of (i) the number of shares that were available for issuance in the aggregate under prior option plans on the effective date of the 2011 Plan, including the shares subject to outstanding awards under those plans, that were transferred to the new 2011 Plan on the effective date, plus (ii) an additional 265,597 shares of the Company’s common stock so that the initial total shares reserve is 6,277,777. The share reserve will automatically increase on the first trading day of January each calendar year during the term of the 2011 Plan, beginning with calendar year 2012, by an amount equal to 5% of the total number of shares of common stock outstanding on the last trading day in the immediately preceding calendar month. In no event, however, will any such annual increase exceed 2,500,000 shares, and the Board of Directors may decide to waive the automatic increase. The Board of Directors waived the automatic increase of share reserve in 2022 and 2023. In September 2021, the Board of Directors approved the amendment of 2011 Plan to extend the termination of the 2011 Plan to September 11, 2031. Stock Options Option activities for the periods presented are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Number of ​ ​ ​ ​ Average ​ ​ Shares ​ Stock ​ Weighted- ​ Remaining ​ ​ Available ​ Options ​ Average ​ Contractual Life ​ for Grant Outstanding Exercise Price (Years) Balances as of January 1, 2022 ​ 1,679,763 ​ ​ 8,194,822 ​ $ 0.02 ​ 6.1 Granted (105,000) ​ 105,000 ​ 0.02 Exercised — ​ (2,459,014) ​ 0.02 Cancelled 1,066,916 ​ (1,066,916) ​ 0.02 Balances as of December 31, 2022 2,641,679 ​ 4,773,892 ​ 0.02 5.1 RSUs granted (2,099,970) ​ — ​ — Exercised — ​ (1,130,481) ​ 0.02 Cancelled 64,117 ​ (64,117) ​ 0.02 Balances as of December 31, 2023 605,826 ​ 3,579,294 ​ 0.02 5.5 Vested as of December 31, 2023 ​ ​ ​ 3,311,859 ​ $ 0.02 ​ 5.3 Vested and expected to be vest as of December 31, 2023 ​ ​ ​ 3,569,024 ​ $ 0.02 ​ 5.5 ​ The weighted average grant date fair value of options granted during the year ended December 31, 2022, was $0.01 per share. There were no options granted during the year ended December 31, 2023. As of December 31, 2023, there was $2,000 of unrecognized compensation cost related to employee stock option compensation arrangements which is expected to be recognized on a straight-line basis over a weighted average period of 1.3 years. There were no capitalized stock-based compensation costs or recognized stock-based compensation tax benefits during the years ended December 31, 2023 and 2022. ​ 9. Stock-Based Compensation, Determining Fair Value of Stock Options The fair value of each grant of stock options was determined by the Company and its Board of Directors using the methods and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment to determine. Valuation Method The Company estimates the fair value of its stock options using the Black-Scholes option-pricing model. Expected Term The expected term represents the period that the stock-based awards are expected to be outstanding. The option grants qualify to be “plain vanilla,” and the Company used the simplified method to determine the expected term. The simplified method calculates the expected term as the average of the time-to-vesting and contractual life of the option. Fair Value of Common Stock The fair value of the common stock underlying the stock options has historically been determined by the Company’s Board of Directors, with input from management. The Board of Directors is comprised of a majority of nonemployee directors with significant experience investing and operating companies in the semiconductor industry. As such, the Company believes that the Board of Directors has the relevant experience and expertise to determine a fair market value of the common stock on each respective grant date. Because there has been no public market for the Company’s common stock, the Board of Directors has determined the fair market value of the common stock at the time of the option grant by considering a number of objective and subjective factors including valuations of comparable companies, sales of convertible preferred stock to unrelated third parties, operating and financial performance, lack of liquidity of capital stock and general and industry-specific economic outlook, amongst other factors. The fair value of the underlying common stock shall be determined by the Board of Directors until such time that the Company’s common stock is listed on an established stock exchange or national market system. Risk-Free Interest Rate The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for zero coupon U.S. Treasury notes with maturities approximately equal to the expected term of the options. Expected Volatility The expected volatility was based on the historical stock volatilities of several of the Company’s publicly listed peers over a period approximately equal to the expected term of the options as the Company did not have a sufficient trading history to use the volatility of its own common stock. Expected Dividend Yield The expected dividend yield has been zero as the Company has never paid dividends on common stock and does not expect to pay dividends on common stock. ​ 9. Stock-Based Compensation, Determining Fair Value of Stock Options, Forfeiture Rate The Company estimates its forfeiture rate based on an analysis of its actual forfeitures and will continue to evaluate the adequacy of the forfeiture rate based on actual forfeiture experience, analysis of employee turnover behavior and other factors. The impact from a forfeiture rate adjustment will be recognized in full in the period of adjustment, and if the actual number of future forfeitures differs from that estimated, the Company may be required to record adjustments to stock-based compensation expense in future periods. Summary of Assumptions The fair value of the employee stock options were estimated on the grant dates using a Black-Scholes option-pricing model with the following weighted average assumptions: ​ ​ ​ ​ ​ ​ 2022 Estimated term (in years) 5.8 ​ Risk-free interest rate 1.85 % Expected volatility 65 % Expected dividend yield 0 % ​ Restricted Stock Units Restricted Stock Units (“RSUs”) granted to employees and board members under 2011 Plan vest over 4 years RSUs activities for the fiscal year ended December 31, 2023, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of ​ Average Grant ​ Shares Date Fair Value Nonvested, outstanding at December 31, 2022 — ​ $ — Granted 2,099,970 ​ 1.15 Vested — ​ — Cancelled — ​ — Nonvested, outstanding at December 31, 2023 2,099,970 ​ $ 1.15 ​ As of December 31, 2023, there was $1,990,000 of unrecognized compensation cost related to RSUs, which is expected to be recognized on a straight-line basis over a weighted average period of 3.95 years.

Income Taxes_2

Income Taxes	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Income Taxes
Income Taxes	12. Income Taxes For the three months ended March 31, 2024 and 2023, the Company recorded income tax expense of $59,000 and $50,000, respectively. The effective tax rate is 7.2% and 3.7% for the three months ended March 31, 2024 and 2023, respectively. For financial reporting purposes, the Company’s effective tax rate used for the interim periods is based on the estimated full-year income tax rate. For the three months ended March 31, 2024, the Company’s effective tax rate differs from the statutory rate primarily due to the valuation allowance recorded against the net deferred tax asset balance. As of March 31, 2024 the Company had unrecognized tax benefits of $3.1 million of which $1.7 million would currently affect the Company’s effective tax rate if recognized due to the Company’s deferred tax assets being fully offset by a valuation allowance. The Company does not anticipate that the amount of unrecognized tax benefits relating to tax positions existing as of March 31, 2024 will significantly increase or decrease within the next twelve months. There was no interest expense or penalties related to unrecognized tax benefits recorded as of March 31, 2024. A number of years may elapse before an uncertain tax position is audited and finally resolved. While it is often difficult to predict the final outcome or the timing of resolution of any particular uncertain tax position, the Company believes that its reserves for income taxes reflect the most likely outcome. The Company adjusts these reserves, as well as the related interest, in light of changing facts and circumstances. Settlement of any particular position could require the use of cash. Currently the Company is not under examination by any taxing authority.	10. Income Taxes Determining the provision for income taxes, income taxes payable, and deferred tax assets and liabilities involves judgment. The Company calculates and provides for income taxes in each of the tax jurisdictions in which it operates, which involves estimating current tax exposures as well as making judgments regarding the recoverability of deferred tax assets in each jurisdiction. The estimates used could differ from actual results, and this may have a significant impact on financial position, operating results and cash flows in future periods. 10. Income Taxes, continued The domestic and foreign components of income (loss) before provision for income taxes were as follows for the years ended December 31: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Domestic ​ $ (19,910) ​ $ (30,559) Foreign ​ (2,018) ​ 4,268 Loss before provision for income taxes ​ $ (21,928) ​ $ (26,291) ​ ​ The provision for income taxes for the years ended December 31, 2023 and 2022 consisted of the following: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Current ​ ​ Federal ​ $ 215 ​ $ 128 State ​ 1 ​ 1 Foreign ​ 325 ​ (8) Total current ​ 541 ​ 121 ​ ​ ​ ​ ​ ​ ​ Deferred ​ ​ Federal ​ — ​ — State ​ — ​ — Foreign ​ — ​ — Total deferred ​ — ​ — Total provision for income taxes ​ $ 541 ​ $ 121 ​ The reconciliation of federal statutory income tax to the Company’s provision for income taxes is as follows: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Expected benefit at statutory federal rate ​ $ (4,941) ​ $ (6,717) State tax — net of federal benefit ​ 72 ​ 100 Research and development credits ​ — ​ (564) Foreign income/losses taxed at different rates ​ 14 ​ 15 Unrecognized tax benefits ​ 276 ​ 126 Stock-based compensation ​ 8 ​ 3 Interest expense ​ 333 ​ 233 Remeasurements of net defined benefit liabilities ​ 5 ​ — Exchange rate difference ​ 287 ​ 551 Change in tax rate ​ (242) ​ (92) True-up deferred taxes ​ 1,382 ​ 3,254 True-up payable ​ 75 ​ — Accumulated deficit ​ 67 ​ 10 Change in valuation allowance ​ 3,182 ​ 3,246 Other ​ 23 ​ (44) Total provision for income taxes ​ $ 541 ​ $ 121 ​ ​ 10. Income Taxes, For the years ended December 31, 2023 and 2022, the Company’s provision for income taxes differed from the federal statutory tax rate due primarily to the full valuation allowance for federal and state purposes, true-up deferred taxes, research and development credits, and exchange rate differences. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Deferred tax assets ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 79,078 ​ $ 78,583 Capitalized costs ​ 5,409 ​ 3,095 Accruals and reserves ​ 4,610 ​ 4,830 Inventory reserves ​ 267 ​ 402 Stock compensation ​ 382 ​ 368 Loss on unrealized currency translation ​ 166 ​ 160 Research and development credits ​ 2,490 ​ 2,490 Financial guarantee liabilities ​ 5,410 ​ 5,320 Lease liability ​ 197 ​ 4 Provision for credit losses ​ 368 ​ 119 Gross deferred tax assets ​ 98,377 ​ 95,371 Valuation allowance ​ (97,628) ​ (94,446) Net deferred tax assets ​ 749 ​ 925 Deferred tax liabilities ​ ​ ​ ​ ​ ​ Revaluation of convertible promissory notes ​ (448) ​ (742) Contract assets ​ (3) ​ (8) ROU assets ​ (298) ​ (175) Gross deferred tax liabilities ​ (749) ​ (925) Net deferred income tax ​ $ — ​ $ — ​ The Company provided a valuation allowance for net operating losses, credits and other deferred tax assets of its United States and foreign entities. A valuation allowance is provided when, based upon the available evidence, management concludes that it is more-likely-than-not that some portion of the deferred tax assets will not be realized. The Company maintained a valuation allowance as of December 31, 2023 and 2022 due to the uncertainty of realizing future tax benefits from its net operating loss carryforwards and other deferred tax assets. The valuation allowance increased by $3.2 million for both the years ended December 31, 2023 and 2022, respectively. The Company had net operating loss carryforwards (“NOL”) for federal, state and foreign income tax purposes of approximately $334 million, $49 million and $27 million, respectively, as of December 31, 2023. State NOL will begin to expire in 2028 and $123 million of the Company’s federal NOL will last indefinitely (limited to 80% of taxable income in a given year). As of December 31, 2023, the Company had federal and state research credit carryforwards of approximately $2.4 million and $2.3 million, respectively. The federal research credit carryforwards will begin to expire in 2025 while the California research credits carryforward have an indefinite life. ​ 10. Income Taxes, ​ Section 382 of the Internal Revenue Code of 1986, as amended, imposes restrictions on the utilization of NOL carryforwards and research tax credits in the event of a change in ownership. While the Company believes that it is probable that its ability to utilize NOL carryforwards may be limited due to past ownership changes, the Company has not yet completed an analysis to determine the amount of such limitation, if any. A reconciliation of the unrecognized tax benefits (“UTBs”) as of December 31, 2023 and 2022 is as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Beginning gross UTBs ​ $ 3,203 ​ $ 3,106 Additions for tax positions taken in a prior year ​ — ​ (35) Additions for tax provision taken in the current year ​ 319 ​ 1,093 Adjustments for tax positions for changes in currency translation ​ 95 ​ (223) Reductions for tax positions taken in the prior year ​ 1,051 ​ (270) Reductions for tax positions taken in the prior year due to statutes lapsing ​ (1,585) ​ (468) Ending gross UTBs ​ 3,083 ​ 3,203 UTBs offset by deferred tax assets and/or valuation allowance ​ (1,419) ​ (1,714) Net UTBs ​ $ 1,664 ​ $ 1,489 ​ As of December 31, 2023, the total amount of gross unrecognized tax benefits was $3.1 million. The amount of unrecognized tax benefits that, if recognized, would affect the Company’s effective tax rate is $1.7 million as of December 31, 2023. The remaining amounts in unrecognized tax benefits would not impact the rate as they are offset by valuation allowances. As of December 31, 2023 and 2022, accrued interest and penalties were $522,000 and $449,000, respectively. The Company recognizes interest and penalties related to unrecognized tax benefits within the provision for income taxes line in the accompanying consolidated statements of operations. Accrued interest and penalties are included within the related tax liability line in the consolidated balance sheets. The Company has classified the unrecognized tax benefits as long term, as it does not expect them to be realized over the next 12 months. The Company also does not expect its unrecognized tax benefits to change significantly over the next 12 months. The Company files income tax returns in the U.S. federal jurisdiction, California and in many foreign jurisdictions. The Company’s tax years for 2020 and forward are subject to examination by the U.S. tax authorities. The Company’s tax years for 2019 and forward are subject to examination by various state tax authorities. However, due to the fact that the Company had loss and credits carried forward in some jurisdictions, certain items attributable to technically closed years are still subject to adjustment by the relevant taxing authority through an adjustment to tax attributes carried forward to open years. The Company files U.S. and foreign income tax returns with varying statutes of limitations. Due to the Company’s net carryover of unused operating losses, all years remain subject to future examination by tax authorities.

Employee Benefit Plans_2

Employee Benefit Plans	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Employee Benefit Plans
Employee Benefit Plans	13. Employee Benefit Plans Under Korean law, the Company is required to make severance payments to Korean employees leaving its employment. The Company’s severance pay liability to its Korean employees, which is a function of the salary of each employee’s years of employment and severance factor, is reflected in the accompanying condensed consolidated balance sheets as the net defined benefit liabilities on an accrual basis. The net liability for severance payments as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 Liability for severance payments, beginning ​ $ 7,764 ​ $ 7,997 Deposit ​ (276) ​ (308) Liability for severance payments, ending ​ $ 7,488 ​ $ 7,689 ​	11. Employee Benefit Plans The Company sponsors a 401(k) defined contribution plan covering all U.S. employees. Contributions made by the Company are determined annually by the Board of Directors. Employer contributions under this plan amounted to $64,000 and $71,000 for the years ended December 31, 2023 and 2022, respectively. Under Korean law, the Company is required to make severance payments to Korean employees leaving its employment. The Company’s severance pay liability to its Korean employees, which is a function of the salary of each employee’s years of employment and severance factor, is reflected in the accompanying consolidated balance sheets as net defined benefit liabilities on an accrual basis. As of December 31, 2023 and 2022, the net liability for severance payments consisted of: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Liability for severance payments ​ $ 7,997 ​ $ 7,248 Deposit ​ (308) ​ (343) ​ ​ $ 7,689 ​ $ 6,905 ​

Related Party Transactions_2

Related Party Transactions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Related Party Transactions
Related Party Transactions	14. Related Party Transactions A summary of balances and transactions with the related parties who are stockholders of the Company were as follows as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 ​ ​ Anapass Kyeongho Lee ​ Anapass Kyeongho Lee Borrowings ​ $ 9,653 ​ $ 824 ​ $ 10,082 ​ $ 1,474 Other current liabilities ​ 106 ​ 87 ​ 212 ​ 182 ​ For each of the three months ended March 31, 2024 and 2023, the Company recorded $0.1 million of interest expense with Anapass, Inc. in the condensed consolidated statements of operations. During the three months ended March 31, 2024 and 2023, the Company recorded $22,000 and $26,000, respectively, of interest expense with Kyeongho Lee in the condensed consolidated statements of operations.	12. Related Party Transactions A summary of balances and transactions with the related parties who are stockholders of the Company as of and for the years ended December 31, 2023 and 2022, are approximately as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ 2023 ​ 2022 ​ Anapass Kyeongho Lee Anapass Kyeongho Lee Borrowings ​ $ 10,082 ​ $ 1,474 ​ $ 10,257 ​ $ 1,690 Other current liabilities ​ 212 ​ 182 ​ 11 ​ 150 Interest expense ​ 548 ​ 110 ​ 389 ​ 140 ​

Segments and Geographical Infor

Segments and Geographical Information	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Segments and Information
Segments and Geographical Information	15. Segments and Information The Company operates in one segment. Revenue information by geographic region is presented in Note 4 to these condensed consolidated financial statements. Long-lived assets by geographic region were as follows as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 South Korea ​ $ 1,170 ​ $ 1,363 United States ​ 817 ​ 930 Total long-lived assets ​ $ 1,987 ​ $ 2,293 ​	13. Segments and Geographical Information The Company operates in one segment. Revenue information by geographic region is presented in Note 1 to these consolidated financial statements. Long-lived assets by geographic region for the years ended December 31, 2023 and 2022 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 United States ​ $ 930 ​ $ 1,295 South Korea ​ 1,363 ​ 626 Total long-lived assets ​ $ 2,293 ​ $ 1,921 ​

Subsequent Events_2

Subsequent Events	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Subsequent Events
Subsequent Events	17. Subsequent Events Purchase Agreement and Registration Rights Agreement In April 2024, the Company entered into a common stock purchase agreement (the “Purchase Agreement”) and a related registration rights agreement (the “Registration Rights Agreement”) with B. Riley Principal Capital II, LLC (“B. Riley Principal Capital II”). Upon the terms and subject to the satisfaction of the conditions set forth in the Purchase Agreement, the Company has the right, in its sole discretion, to sell to B. Riley Principal Capital II, from time to time, up to $50.0 million in aggregate gross purchase price of shares of the Company’s common stock, subject to certain limitations contained in the Purchase Agreement, during the term of 24 months M-Venture Investment, Inc. In April 2024, the Company executed an amendment with M-Venture Investment, Inc. for the KRW 4.0 billion ($3.0 million) term loan outstanding, pursuant to which the Company repaid KRW 2.0 billion ($1.5 million) in April 2024 and extended the maturity date from October 2024 to May 2024 (see Note 7). In April 2024, the Company executed an amendment with M-Venture Investment, Inc. for the KRW 6.0 billion ($4.4 million) term loan outstanding, pursuant to which the maturity date for both draws were amended. The maturity date for the principal amount of KRW 1.0 billion ($0.7 million) was extended from April 2024 to June 2024. The maturity date for the principal amount of KRW 5.0 billion ($3.7 million) was extended from April 2024 to July 2024 (see Note 7). Historical Convertible Promissory Notes In April 2024, the Company repaid in full a historical convertible promissory note that was issued in 2021 with a principal amount of $0.6 million (see Note 7). Share Reserve In May 2024, the board of directors of the Company approved 3,983,334 shares as the maximum number of shares of Common Stock that may be issued pursuant to 2024 Plan, and 600,000 shares as reserved share amount of 2024 Employee Stock Purchase Plan.	14. Subsequent Events Management has evaluated all transactions and events through March 29, 2024, the date on which these consolidated financial statements were available to be issued, and other than the following there are no other items that would adjust the consolidated financial statements or require additional disclosures. In January 2024, the maturity date of the loan of $776,000 from i Best Investment was extended for two three In January 2024, GCT R&D, a subsidiary of the Company, borrowed a short term loan of $237,000 from NJ Holdings, a related party. The loan had a seven In January, February and March 2024, GCT R&D repaid term loan of $613,000 to Kyeongho Lee. In February and March 2024, the Company issued convertible promissory notes of $11.3 million to Korean investors. The convertible promissory notes mature in February and March 2027 and have a conversion price of $6.67 per share. The convertible promissory notes will be automatically converted to common stock upon the closing of the transaction with Concord Acquisition Corp III discussed in Note 1. In February 2024, the Company issued a convertible promissory note of $5.0 million to a U.S. company. The convertible promissory note matures in February 2026 and has a conversion price of $10.00 per share. The convertible promissory note holder can demand conversion to common stock on or after the earlier of i) completion of the SPAC transaction and ii) six On March 15, 2024, the Board of Directors approved a term sheet of equity line of credit (ELOC) facility proposed by an investment banking firm. Under this facility, the Company may issue and sell shares common stock, from time to time, to an affiliate of the investment banking firm at a price equal to a specified percentage of VWAP (Volume Weighted Average Price) of the stock on NYSE up to an aggregate amount of $50 million. The term sheet is not binding and subject to completion of definitive agreements, and the Board of Directors delegated authority to the management to negotiate and finalize definitive agreements for the facility. On March 26, 2024, Concord Acquisition Corp III consummated its Business Combination with the Company, pursuant to the Business Combination Agreement, dated as of November 2, 2023, and changed name to GCT Semiconductor Holding, Inc. (“GCT Holding”). On March 26, 2024, in accordance with the terms of the Business Combination Agreement, the Company’s all outstanding warrants were assumed by GCT Holding. On March 26, 2024, the Company terminated the 2011 Plan. As a result, all outstanding options and RSUs under the 2011 Plan were assumed by GCT Holding in accordance with the terms of the Business Combination Agreement. On March 26, 2024, the convertible promissory notes (“CPN”) principal and related accrued interest balance of $32,087,000 and the convertible notes to SPAC shares (“CVT”) principal and related accrued interest balance of $13,370,000 were converted into 4,258,223 and 2,004,535 shares of GCT Holding common stock, respectively. On March 26, 2024, as consideration for the $30.2 million PIPE Financing, the Company issued 4,529,967 shares of GCT Holding common stock to PIPE Shareholders.

The Company and Summary of Si_2

The Company and Summary of Significant Accounting Policies (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Organization and Liquidity
Business		Business GCT Semiconductor, Inc. (“GCT”) is a fabless semiconductor company that designs, develops and markets integrated circuits for the global wireless semiconductor industry. GCT was originally incorporated in California on June 15, 1998 and was reincorporated in Delaware on February 21, 2001. In June 2000, GCT incorporated a wholly-owned subsidiary, GCT Asia Pacific, Inc. (“GCT AP”) in Seoul, South Korea. GCT AP was created to develop markets in the Asia Pacific region. In June 2000, GCT acquired Advanced CoreTech, Inc. (“ACT”), a South Korean corporation, to enhance its research and development (“R&D”) capacity for all product lines. Subsequent to the acquisition, ACT changed its name to GCT Research, Inc. (“GCT R&D”). In October 2012, GCT acquired MTH, Inc. (“MTH”), a South Korean corporation, to acquire 2G/3G LTE technology and further enhance research and development. To date, GCT and its wholly-owned subsidiaries’, GCT AP, GCT R&D and MTH (collectively, the “Company”) operations have been funded primarily through the issuance of redeemable convertible preferred stock, promissory notes, bank borrowings and issuance of common stock. On November 2, 2023, the Company entered into a definitive business combination agreement with Concord Acquisition Corp III, a publicly traded special purpose acquisition company, that would result in the Company becoming a publicly listed company subject to closing. Upon closing of the transaction, the combined company will be named GCT Semiconductor and will be traded on the NYSE under the new ticker symbol “GCTS.” The transaction is expected to be completed in the first quarter of 2024.
Basis of Presentation		Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”)
Principles of Consolidation		Principles of Consolidation The accompanying consolidated financial statements include the accounts of GCT and its wholly-owned subsidiaries, GCT AP, GCT R&D and MTH. All significant intercompany balances and transactions have been eliminated in consolidation.
Net Loss Per Common Share		Net Loss Per Common Share Basic net loss per common share is computed by dividing net loss attributable to common stockholders (net loss adjusted for preferred stock dividends declared or accumulated) by the weighted average number of common shares outstanding during the period. All participating securities are excluded from basic weighted average shares outstanding. In computing diluted net loss attributable to common stockholders, undistributed earnings are re-allocated to reflect the potential impact of dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing net loss attributable to common stockholders by diluted weighted average shares outstanding, including potentially dilutive securities, unless anti-dilutive. Potentially dilutive securities that were excluded from the computation of diluted net loss per common share consist of the following: ​ ​ ​ ​ ​ ​ ​ 2023 2022 Convertible promissory notes 9,827,666 9,688,740 Warrants 9,200,000 3,942,853 Options 3,579,294 4,773,892 Restricted Stock Units (RSU) 2,099,970 — Total 24,706,930 18,405,485 ​ As all potentially dilutive securities are anti-dilutive as of December 31, 2023 and 2022, diluted net loss per common share is the same as basic net loss per common share for each period.
Use of Estimates	Use of Estimates The preparation of the accompanying condensed consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates, and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. These judgments, estimates and assumptions are used for but not limited to revenue recognition, provision for credit losses, inventory obsolescence, recoverability of long-lived assets, certain accrued expenses, stock-based compensation, determination of fair value of the Company’s convertible promissory notes, common stock (prior to the reverse recapitalization), warrant labilities and stock options, and deferred income taxes including related valuation allowances. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates, and these differences may be material.	Use of Estimates The preparation of the accompanying consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates, and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. These judgments, estimates and assumptions are used for but not limited to: revenue recognition; provision for credit losses; warranty obligations; inventory obsolescence; recoverability of long-lived assets; stock-based compensation; determination of fair value of the Company’s convertible promissory notes, common stock, and stock options, and deferred income taxes including related valuation allowances. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates, and these differences may be material.
Going Concern, Liquidity and Management's Plan		Going Concern, Liquidity and Management’s Plan The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Company has incurred operating losses and negative cash flows from operating activities for each of the two years in the period ended December 31, 2023. As of December 31, 2023, the Company had an accumulated deficit of approximately $549.7 million and negative working capital of approximately $101.8 million. During the year ended December 31, 2023, the Company incurred a net loss of approximately $22.5 million and used cash from operations of approximately $8.8 million. These factors raise substantial doubt about the Company’s ability to continue as a going concern for the twelve months from the date of this report. The Company’s ability to continue to meet its obligations and to achieve its intended business objectives is dependent upon, among other things, negotiating a bank line of credit debt obligation, raising additional capital, and the timely launch of its new products and returning to profitability. Future capital requirements will depend on many factors, including the rate of revenue growth, the selling price of the Company’s products, the expansion of sales and marketing activities, and the timing and extent of research and development efforts. The Company is actively pursuing a transaction with a special purpose acquisition company (“SPAC”) and completed major steps required including the U.S. Security and Exchange Commission (“SEC”) filing and SPAC shareholders’ approval. Management expects the SPAC transaction will be successful and could use the proceeds from the SPAC transaction to support its operations. In the event the proceeds from the SPAC transaction are not enough, the Company will seek additional funding through other means, such as the issuance of debt or equity line of credit. Management’s plans also include managing the Company’s cash burn by controlling expenditures. While the Company has raised capital in the past, there can be no assurance that additional financing will be available at terms acceptable to the Company, if at all. Failure to generate sufficient cash flows from operations, raise additional capital and reduce discretionary spending could have a material adverse effect on the Company’s ability to achieve its intended business objectives. The accompanying consolidated financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern.
Cash and Cash Equivalents		Cash and Cash Equivalents The Company considers all highly liquid investments purchased with a remaining maturity of three months or less to be cash equivalents. The Company deposits its cash primarily in checking and money market accounts with high quality financial institutions.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amount of certain financial instruments held by the Company, such as cash equivalents, accounts receivable, contract assets and liabilities, accounts payable, and accrued and other current liabilities, approximate fair value due to their short maturities. The carrying amount of the liabilities for the convertible promissory notes represents their fair value. The carrying amounts of the Company’s bank borrowings and lease liabilities approximate fair value due to the market interest rates that these obligations bear and interest rates available to the Company. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s Level 3 financial instruments consist of convertible promissory notes and warrant liabilities. These financial instruments were valued using valuation techniques that are considered to be a Level 3 fair value measurement .	Fair Value of Financial Instruments The carrying amount of certain financial instruments held by the Company, such as cash equivalents, accounts receivable, contract assets and liabilities, accounts payable, and accrued and other current liabilities, approximate fair value due to their short maturities. The carrying amount of the liabilities for the convertible promissory notes represents their fair value. The carrying amounts of the Company’s bank borrowings, and lease liabilities approximate fair value due to the market interest rates that these obligations bear and interest rates currently available to the Company. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities; Level 2 Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company has no assets with fair value obtained using observable or unobservable markets. The Company did have liabilities with a fair value obtained using unobservable markets (Level 3). The Company’s Level 3 liabilities consist of the redeemable convertible preferred stock warrant liabilities and convertible promissory notes. The convertible promissory notes were valued using a combination of option pricing model and Probability Weighted Expected Return Method (“PWERM”), which is considered to be a Level 3 fair value measurement.
Risk and Uncertainties	Risk and Uncertainties The Company is subject to certain risks and uncertainties and believes changes in any of the following areas could have a material adverse effect on the Company’s future financial position or results of operations or cash flows: new product development, including market receptivity, the ability to satisfy obligations under development agreements with major partners, litigation or claims against the Company based on intellectual property, patent, product regulation or other factors, competition from other products, general economic conditions, the ability to attract and retain qualified employees and ultimately to sustain profitable operations. The semiconductor industry is characterized by rapid technological change, competition, competitive pricing pressures and cyclical market patterns. The Company’s financial results are affected by a wide variety of factors, such as general economic conditions specific to the semiconductor industry and the Company’s particular market, the timely implementation of new products, new manufacturing process technologies and the ability to safeguard patents and intellectual property in a rapidly evolving market. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns. As a result, the Company may experience significant period-to-period fluctuations in condensed consolidated operating results due to the factors mentioned above or other factors. The Company’s revenue may be impacted by its ability to obtain adequate wafer supplies from foundries and back-end production capacity from the Company’s test and assembly subcontractors. The foundries with which the Company currently has arrangements may not be willing or able to satisfy all of the Company’s manufacturing requirements on a timely basis and/or at favorable prices. The Company is also subject to the risks of service disruptions, raw material shortages and price increases by its foundries. Such disruptions, shortages and price increases could harm the Company’s consolidated operating results.	Risk and Uncertainties The Company is subject to certain risks and uncertainties and believes changes in any of the following areas could have a material adverse effect on the Company’s future financial position or results of operations or cash flows: new product development, including market receptivity, litigation or claims against the Company based on intellectual property, patent, product regulation or other factors, competition from other products, general economic conditions, the ability to attract and retain qualified employees and ultimately to sustain profitable operations. The semiconductor industry is characterized by rapid technological change, competition, competitive pricing pressures and cyclical market patterns. The Company’s financial results are affected by a wide variety of factors, such as general economic conditions specific to the semiconductor industry and the Company’s particular market, the timely implementation of new products, new manufacturing process technologies and the ability to safeguard patents and intellectual property in a rapidly evolving market. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns. As a result, the Company may experience significant period-to-period fluctuations in consolidated operating results due to the factors mentioned above or other factors. The Company’s revenue may be impacted by its ability to obtain adequate wafer supplies from foundries and back-end production capacity from the Company’s test and assembly subcontractors. The foundries with which the Company currently has arrangements may not be willing or able to satisfy all of the Company’s manufacturing requirements on a timely basis and/or at favorable prices. The Company is also subject to the risks of service disruptions, raw material shortages and price increases by its foundries. Such disruptions, shortages and price increases could harm the Company’s consolidated operating results.
Concentration Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to the concentration of credit risk consist of cash and cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents primarily with one financial institution located in the United States and another financial institution located in Korea where amounts deposited may exceed Federal Deposit Insurance Corporation or Korea Deposit Insurance Corporation limits. The Company’s accounts receivable balances are primarily derived from revenues earned from customers located in the United States, China, Korea, Japan and Taiwan. The Company performs ongoing credit evaluations of its customers’ and distributors’ financial condition and generally does not require collateral from its customers. The Company’s net revenue and accounts receivable are concentrated among a few significant customers, which could expose the Company to financial risk in the event of adverse developments with these customers. Four customers accounted for approximately 28 percent, 19 percent, 18 percent and 13 percent of the Company’s gross accounts receivable as of March 31, 2024. Four customers accounted for approximately 27 percent, 19 percent, 14 percent and 10 percent of the Company’s gross accounts receivable as of December 31, 2023. Two customers accounted for approximately 61 percent and 24 percent of the Company’s total net revenues for the three months ended March 31, 2024. Four customers accounted for approximately 28 percent, 28 percent, 25 percent, and 10 percent of the Company’s total net revenues for the three months ended March 31, 2023. Management closely monitors the creditworthiness and performance of these key customers and has established credit limits and terms to mitigate potential credit risks. The Company also continues to diversify its customer base and explore opportunities to reduce its reliance on a few major customers.	Concentration Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash and cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents primarily with one financial institution located in the United States and another financial institution located in Korea where amounts deposited may exceed Federal Deposit Insurance Corporation or Korea Deposit Insurance Corporation limits. The Company’s accounts receivable are primarily derived from revenues earned from customers located in the United States, China, Korea, Japan and Taiwan. The Company performs ongoing credit evaluations of its customers’ and distributors’ financial condition and generally does not require collateral from its customers. Some of the components used in the Company’s products are purchased from a limited number of sources located in Asia. The loss of any of these suppliers may cause the Company to incur additional costs to transition these relationships, result in delays in the delivery of its products or cause the Company to carry excess or obsolete inventory. GCT is a fabless semiconductor company and relies on third parties for all of its manufacturing operations, including wafer fabrication, assembly, testing, warehousing, and shipping and logistics. The Company relies on UMC Company (USA) (“UMC”) and Samsung Semiconductor System LSI Division to manufacture substantially all of the wafers for its products. The Company uses third-party vendors to assemble, package and test the products. The Company primarily uses the services of Tianshui Huatian Co., Ltd., ATSemicon Co., Ltd. Amkor, and STATS ChipPAC Ltd. for assembly, and Advanced Semiconductor and Engineering, Inc. and Giga Solution Tech Co., Ltd. for testing. The Company depends on these third-party vendors to supply services and material of a requested quantity in a timely manner that meets the Company’s standards for yield, cost and manufacturing quality. The Company does not have long-term supply agreements with its third-party vendors other than a framework agreement with UMC. If one or more of these vendors terminates its relationship with the Company, or if the Company encounters any problems with its manufacturing supply chain, it could adversely impact the Company’s ability to ship products to its customers on time and in the quantity required, which in turn could cause an unanticipated decline in sales and possibly damage customer relationships.
Accounts Receivable and Provision for Credit Losses		Accounts Receivable and Provision for Credit Losses Trade accounts receivable are recorded at invoiced amounts, net of provision for credit losses, if applicable, and do not bear interest. The provision for credit losses is based on the Company’s assessment of the collectability of its customer accounts. The Company reviews the provision for credit losses by considering certain factors such as historical experience, industry data, credit quality, age of balances and current economic conditions that may affect a customer’s ability to pay. Uncollectible receivables are written off when all efforts to collect have been exhausted and recoveries are recognized when they are recovered. The Company determined that provisions for credit losses of approximately $1,644,000 and $549,000 were necessary as of December 31, 2023 and 2022, respectively.
Inventory		Inventory Inventory is stated at the lower of cost or net realizable value. Cost is determined by actual cost on a first-in, first-out basis. The Company’s inventory is concentrated in high technology parts and components that may be specialized in nature or subject to rapid technological obsolescence. The Company considers the following characteristics, in addition to the specialized nature and potential technological obsolescence of the Company’s inventory, including age of inventory on hand and that the inventory may be returned from distributors, historical sales levels, estimated future demand within the next six months, inventory commitments or potential product revisions, in evaluating net realizable value. For the years ended December 31, 2023 and 2022, the Company wrote-down approximately $358,000 and $338,000, respectively, of inventory into cost of net revenues. Once inventory has been written down below cost, it is not subsequently written up.
Property and Equipment, Net		Property and Equipment, Net Property and equipment are recorded at cost less accumulated depreciation and amortization. Depreciation is recognized on a straight-line basis over the estimated useful lives of the assets, generally three
Leases		Leases The Company is a lessee in several noncancellable (1) operating leases, primarily for office equipment, warehouses, and office space, and (2) finance leases, for certain machinery and information technology (“IT”) equipment. The Company accounts for leases in accordance with the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) Topic 842, Leases (“Topic 842”). The Company determines if an arrangement is or contains a lease at contract inception. The Company recognizes a right-of-use (“ROU”) asset and a lease liability at the lease commencement date. For operating and finance leases, the lease liability is initially measured at the present value of the unpaid lease payments at the lease commencement date. The lease liability is subsequently measured at amortized cost using the effective-interest method. Key estimates and judgments include how the Company determines (1) the discount rate it uses to discount the unpaid lease payments to present value, (2) lease term, and (3) lease payments. ● ● ● – – – – The ROU asset is initially measured at cost, which comprises the initial amount of the lease liability adjusted for lease payments made at or before the lease commencement date, plus any initial direct costs incurred less any lease incentives received. For operating leases, the ROU asset is subsequently measured throughout the lease term at the carrying amount of the lease liability, plus initial direct costs, plus (minus) any prepaid (accrued) lease payments, less the unamortized balance of lease incentives received. Lease expense for lease payments is recognized on a straight-line basis over the lease term. For finance leases, the ROU asset is subsequently amortized using the straight-line method from the lease commencement date to the earlier of the end of its useful life or the end of the lease term unless the lease transfers ownership of the underlying asset to the Company or the Company is reasonably certain to exercise an option to purchase the underlying asset. In those cases, the ROU asset is amortized over the useful life of the underlying asset. Amortization of the ROU asset is recognized and presented separately from interest expense on the lease liability. Variable lease payments associated with the Company’s leases are recognized when the event, activity, or circumstance in the lease agreement on which those payments are assessed occurs. Variable lease payments are presented as operating expenses in the Company’s consolidated statements of operations in the same line item as expenses arising from fixed lease payments (operating leases) or amortization of the ROU asset (finance leases). ROU assets for operating and finance leases are occasionally reduced by impairment losses. The Company uses the long-lived assets impairment guidance in ASC Subtopic 360-10, Property, Plant, and Equipment – Overall, to determine whether an ROU asset is impaired, and if so, the amount of the impairment loss to recognize. The Company monitors for events or changes in circumstances that require a reassessment of one of its leases. When a reassessment results in the remeasurement of a lease liability, a corresponding adjustment is made to the carrying amount of the corresponding ROU asset unless doing so would reduce the carrying amount of the ROU asset to an amount less than zero. In that case, the ROU asset is reduced to zero and the remainder of the adjustment is recorded in profit or loss. Operating lease and finance lease ROU assets are presented as operating lease right-of-use assets and finance lease right-of use assets, respectively, on the consolidated balance sheets. The current portion of finance lease liabilities is included in current installments of obligations under finance leases, and the long-term portion is included in obligations under finance leases on the consolidated balance sheets. The Company has elected not to recognize ROU assets and lease liabilities for short-term leases of transportation equipment that have a lease term of 12 months or less. The Company has elected not to apply the short-term lease recognition and measurement exemption for other classes of leased assets. The Company recognizes the lease payments associated with its short-term transportation equipment leases as an expense on a straight-line basis over the lease term. Variable lease payments associated with these leases are recognized and presented in the same manner as for all other Company leases. The Company’s leases generally include non-lease maintenance services (i.e. equipment maintenance or common area maintenance). For leases of assets other than office equipment, the Company allocates the consideration in the contract to the lease and non-lease maintenance component based on each component’s relative stand-alone price. The Company determines stand-alone prices for the lease components in those leases based on the prices for which other lessors lease similar assets on a stand-alone basis. The Company determines stand-alone prices for the non-lease components (i.e. maintenance services) in those leases based on the prices that several suppliers charge for maintenance services for similar assets on a stand-alone basis. If observable stand-alone prices are not readily available, the Company estimates the stand-alone prices maximizing the use of observable information. For leases of office equipment, the Company has elected the practical expedient to account for the lease and non-lease maintenance components as a single lease component. Therefore, for those leases, the lease payments used to measure the lease liability include all the fixed consideration in the contract.
Impairment of Long-Lived Assets		Impairment of Long-Lived Assets The Company has long-lived assets such as tangible property and equipment, and identified intangible assets consisting of acquired patents and core technology. When events or changes in circumstances occur that could indicate the carrying value of long-lived assets may not be recoverable, the Company assesses recoverability by determining whether the undiscounted cash flows estimated to be generated by those assets are less than the carrying amounts of those assets. If the undiscounted cash flow is less, an impairment charge is recognized for the excess of the carrying amounts of these assets over the fair values. Fair values are determined by discounted future cash flows, appraisals or other methods. During the years ended December 31, 2023 and 2022, the Company did not record any impairment from long-lived assets.
Revenue Recognition		Revenue Recognition The Company’s revenues are generated by the sale of 4G mobile semiconductor solutions consisting of product and platform solutions aimed at the 4G LTE and WiMax industries, development services and technical advice and maintenance services. To determine when revenues are recognized, the Company performs the following five steps: (1) identify the contract(s) with a customer, (2) identify the performance obligation in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) we satisfy a performance obligation in accordance with ASC Topic 606, Revenue from Contracts with Customers. The revenues from product sales are identified and determined pursuant to purchase orders. The Company considers a performance obligation satisfied once it has transferred control of a good or product to a customer, meaning the customer has the ability to direct the use and obtain the benefit of the product, which is generally at the time of shipment. Service revenues are identified and determined based on each service agreement and recognized over time or at a point in time depending on the evaluation of when the customer obtains control of the promised goods or services, which is generally as services are rendered. For contracts that include multiple performance obligations, the Company allocates revenue to each performance obligation based on estimates of the relative stand-alone selling price that the Company would charge the customer for each promised product or service. Disaggregation of revenues from contracts with customers is as following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2023 (in thousands) ​ Product Revenues ​ Service Revenues ​ Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 10,968 ​ $ — ​ $ 10,968 Over time ​ — ​ 5,060 ​ 5,060 Total ​ $ 10,968 ​ $ 5,060 ​ $ 16,028 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2022 (in thousands) Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 12,977 ​ $ — ​ $ 12,977 Over time ​ — ​ 3,692 ​ 3,692 Total ​ $ 12,977 ​ $ 3,692 ​ $ 16,669 Net revenues categorized by customer location are as follows for the years ended December 31: ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues from external customers (in thousands) ​ 2023 ​ 2022 United States $ 5,056 $ 4,379 China ​ 4,745 ​ 5,608 Korea ​ 4,260 ​ 1,360 Germany ​ 1,422 ​ — Taiwan ​ 543 ​ 4,639 Other ​ 2 ​ 25 Singapore ​ — ​ 658 Total ​ $ 16,028 ​ $ 16,669 ​ Contract Assets and Liabilities Contract assets primarily represent revenue earnings over time for which the Company does not presently have an unconditional right to payment (generally not yet billable) based on the terms of the contracts. The Company does not have impairment losses associated with contracts with customers for the years ended December 31, 2023 and 2022. Contract liabilities consist of fees invoiced to or paid by the Company’s customer for which the associated performance obligations have not been satisfied and revenue has not been recognized based on the Company’s revenue recognition criteria described above. Contract assets and liabilities are reported in a net position on an individual contract basis at the end of each reporting period. Contract assets are classified as current in the consolidated balance sheets when the Company expects to complete the related performance obligations and invoice the customers within one year of the balance sheet date, and as long-term when the Company expects to complete the related performance obligations and invoice the customers more than one year out from the balance sheet date. Contract liabilities are classified as current in the consolidated balance sheets when the revenue recognition associated with the related customer payments and invoicing is expected to occur within one year of the balance sheet date and as long-term when the revenue recognition associated with the related customer payments and invoicing is expected in more than once year from the balance sheet date. Details of contract assets and liabilities is as following: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ December 31, 2023 ​ December 31, 2022 Contract assets ​ $ 3,439 ​ $ 886 Assets recognized for costs incurred to fulfill a contract (*) ​ 12 ​ 39 Contract liabilities ​ 48 ​ 651 (*)- The balances are included in prepaid expenses and other current assets in the accompanying consolidated balance sheets. As of January 1, 2022, contract assets were approximately $661,000. Assets recognized for costs incurred to fulfill a contract represent costs incurred in relation to a contract development and are intended for use in fulfilling that contract. The costs relate directly to the contract, generate resources that will be used to satisfy the contract and are expected to be recovered. They were therefore recognized as assets from costs to fulfill a contract. The asset is amortized on the basis consistent with the method used in recognizing revenue for the specific contract it relates to. In the current period, management expected that the costs recognized as assets are to be recovered according to the contractual payment schedule. Thus, an impairment loss was not recognized as the expected amount of the remaining consideration minus direct costs which have not been recognized as expenses do not exceed the asset. During the year ended December 31, 2023, there were significant changes in contract assets and liabilities, which are summarized as below: ● ● ● Net revenues recognized in relation to contract liabilities is as follows. ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) December 31, 2023 December 31, 2022 Net revenues recognized that were included in the contract liabilities balance at the beginning of the year ​ $ 651 ​ $ 766
Product Warranty		Product Warranty The Company provides customers with warranty claims for certain products and warranty-related the services are not considered a separate performance obligation. Pursuant to ASC Topic 450, Contingencies, the Company makes estimates of product warranty expense using historical experience rates and accrue estimated warranty expense as a cost of net revenues. The Company estimates the costs of warranty obligations based on historical experience of known product failure rates and anticipated rates of warranty claims, use of materials to repair or replace defective products, and service delivery costs incurred in correcting the product issues. In addition, from time to time, specific warranty accruals may be made if unforeseen technical problems arise.
Concentration of Revenues and Accounts Receivable		Concentration of Revenues and Accounts Receivable The Company’s net revenue and accounts receivable are concentrated among a few significant customers, which could expose the Company to financial risk in the event of adverse developments with these customers. In fiscal 2023, approximately 38% of the Company’s total net revenues were derived from two customers. Moreover, approximately 70% of the total gross accounts receivable was derived from four customers at the end of the reporting period. During fiscal 2022, around 66% of the Company’s total net revenues were derived from four customers. Similar to the concentration of revenue, approximately 90% of the total gross accounts receivable was derived from five customers at the end of the reporting period. Details of external customers, who contribute more than 10% of the Company’s net revenues and gross accounts receivable as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Revenues ​ Accounts Receivable (in thousands) ​ 2023 ​ 2022 ​ 2023 ​ 2022 Customer A $ * $ 4,639 $ * $ 1,228 Customer B ​ 3,031 ​ 2,979 ​ 1,755 ​ 590 Customer C ​ * ​ 1,712 ​ * ​ 1,400 Customer D ​ * ​ 1,670 ​ 661 ​ 687 Customer E ​ * ​ * ​ * ​ 610 Customer F ​ * ​ * ​ 1,250 ​ * Customer G ​ 3,000 ​ * ​ * ​ * Customer H ​ * ​ * ​ 938 ​ * *Less than 10% Management closely monitors the creditworthiness and performance of these key customers and has established credit limits and terms to mitigate potential credit risks. The Company also continues to diversify its customer base and explore opportunities to reduce its reliance on a few major customers.
Cost of Net Revenues		Cost of Net Revenues Cost of net revenues consists of direct and indirect costs related to the manufacture of the Company’s products. Direct costs include wafer costs and costs relating to assembly and testing performed by third-party contract manufacturers. Indirect costs consist of provisions for excess and obsolete inventory, royalties, allocated overhead for employee costs and facility costs, warranty and the amortization of the Company’s production mask sets and certain intangible assets. Shipping and handling costs incurred for inventory purchases and product shipments are recorded in cost of net revenues in the consolidated statements of operations.
Warranty		Warranty The Company generally provides warranties on its products for 12 months and provides for the estimated cost of product warranties at the time the revenue is recognized. The Company regularly monitors product returns and maintains a reserve for warranty expenses based upon its historical experience and any specifically identified failures. As of December 31, 2023 and 2022, the warranty accrual was $55,000 and $64,000 respectively. Details and changes in provisions for product warranties for the years ended December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Beginning balance ​ $ 64 ​ $ 106 Provision ​ 18 ​ — Adjustment to prior provisions ​ (27) ​ (42) Ending balance ​ $ 55 ​ $ 64
Stock-Based Compensation		Stock-Based Compensation Compensation costs related to stock option grants are based on the fair value of the options on the date of grant, net of estimated forfeitures. The Company determines the grant date fair value of the options using the Black-Scholes option-pricing model and the related stock-based compensation expense is generally recognized on a straight-line basis over the period in which an employee is required to provide service in exchange for the options, which generally equals the vesting period. Compensation costs related to RSUs grants are based on the common stock price on the date of grant, net of estimated forfeitures. The related stock-based compensation expense is recognized on a straight-line basis over the vesting period of four (4) years.
Income Taxes		Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities. Valuation allowances are established when necessary to reduce deferred tax assets where, based upon the available evidence, management concludes that it is more-likely-than-not that the deferred tax assets will not be realized. The Company records a liability for the uncertain tax positions taken or expected to be taken on the Company’s tax return when it is more-likely-than-not that the tax position might be challenged despite the Company’s belief that the tax return positions are fully supportable, and additional taxes will be due as a result. To the extent that the assessment of such tax positions changes, for example, based on the outcome of a tax audit, the change in estimate is recorded in the period in which the determination is made. The provision for income taxes includes the impact of provisions for uncertain tax positions. Interest and penalties related to unrecognized tax benefits are included within the provision for income taxes.
Foreign Currency Translation	Foreign Currency Financial statements of foreign subsidiaries that use the local currency as their functional currency are translated into U.S. dollars at the end-of-period exchange rates or at historical exchange rates for purposes of consolidation. Revenues and expenses are translated using average exchange rates during the period. Translation adjustments are included in accumulated other comprehensive loss within stockholders’ deficit. Gains and losses resulting from transactions denominated in a currency other than the functional currency are included in other income, net in the condensed consolidated statements of operations. The Company recognized $1.1 million and $0.7 million foreign currency exchange gains for the three months ended March 31, 2024 and 2023, respectively.	Foreign Currency Translation The Company’s foreign subsidiaries, located in Korea, use the local currency, or Korean won (“KRW”), as their functional currency. Financial statements of the foreign subsidiaries are translated into U.S. dollars at the end-of-period exchange rates except for capital stock issued, capital accounts and accumulated deficit which are translated at historical exchange rates for purposes of consolidation. Revenues and expenses are translated using average exchange rates prevailing during the period. Translation adjustments are included in accumulated other comprehensive income (loss) within stockholders’ deficit. Gains and losses resulting from transactions denominated in a currency other than the functional currency are included in other income (expense), net in the consolidated statements of operations. The Company recognized foreign currency exchange gains and losses for the years ended December 31, 2023 and 2022 presented as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Foreign currency gain, net ​ $ 265 ​ $ 181
Convertible Promissory Notes	Convertible Promissory Notes The Company has elected the fair value option to account for its outstanding convertible promissory notes. Under the fair value option, the convertible promissory notes must be recorded at their initial fair value on the date of issuance, any modification, and at the end of each reporting period end date thereafter. Changes in the estimated fair value of the convertible promissory notes are recognized as non-cash gains or losses in other income, net in the condensed consolidated statements of operations.	Convertible Promissory Notes The Company accounts for its convertible promissory notes under ASC 815, Derivatives and Hedging. According to ASC 815-15-25, an election can be made at the inception of a financial instrument to account for the instrument under the fair value option as per ASC 825, Financial Instruments. The Company has made such an election for its convertible promissory notes. Under the fair value option, the convertible promissory notes must be recorded at their initial fair value on the date of issuance, any modification, and each balance sheet date thereafter. Changes in the estimated fair value of the convertible promissory notes are recognized as non-cash gains or losses in other income (expense), net in the consolidated statements of operations.
Comprehensive Income (Loss)		Comprehensive Income (Loss) Comprehensive income (loss) includes all changes within equity that are not the result of transactions with stockholders. Accumulated other comprehensive loss includes foreign currency translation adjustments arising from the consolidation of the Company’s foreign subsidiaries.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Adopted In August 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) Contracts in Entity’s Own Equity (Subtopic 815-40) In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805) Company adopted this guidance effective January 1, 2024, and noted no material impact on the Company’s condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820) In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740)	Recent Accounting Pronouncements In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”) which significantly changes the way entities recognize impairment of many financial assets by requiring immediate recognition of estimated credit losses expected to occur over their remaining life, instead of when incurred. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments–Credit Losses, which amends Subtopic 326-20 (created by ASU 2016-13) to explicitly state that operating lease receivables are not in the scope of Subtopic 326-20. Additionally, in April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments; in May 2019, the FASB issued ASU 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief; in November 2019, the FASB issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates, and ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses; and in March 2020, the FASB issued ASU 2020-03, Codification Improvements to Financial Instruments, to provide further clarifications on certain aspects of ASU 2016-13 and to extend the nonpublic entity effective date of ASU 2016-13. The changes (as amended) are effective for the Company for annual and interim periods in fiscal years beginning after December 15, 2022. The adoption of ASU 2016-13 did not have a material effect on the consolidated financial statements. In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity. ASU 2020-06 reduces the number of accounting models for convertible instruments and allows more contracts to qualify for equity classification. ASU 2020-06 is effective for the Company’s annual reporting periods beginning after December 15, 2023. Adoption is either a modified retrospective method or a fully retrospective method of transition. Early adoption is permitted, but no earlier than annual periods beginning after December 15, 2020. The Company is currently evaluating the effect the adoption of ASU 2020-06 will have on its consolidated financial statements. In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which provides an exception to fair value measurement for contract assets and contract liabilities related to revenue contracts acquired in a business combination. The ASU requires an entity (acquirer) to recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606. At the acquisition date, an acquirer should account for the related revenue contracts in accordance with Topic 606 as if it had originated the contracts. The ASU is effective for the Company for annual and interim periods in fiscal years beginning after December 15, 2023. Early adoption is permitted. The ASU is applied to business combinations occurring on or after the effective date. The Company is currently evaluating the effect the adoption of ASU 2021-08 will have on its consolidated financial statements. In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. The ASU clarifies that a contractual restriction on the sale of an equity security should not be considered in measuring the fair value of the equity security, and also cannot be recognized as a separate unit of account. The ASU also requires the investor to disclose the fair value of equity securities subject to contractual sale restrictions, the nature and remaining duration of the restriction(s), and the circumstances that could cause a lapse in the restriction(s). The ASU is effective for the Company for annual and interim periods beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the effect the adoption of ASU 2022-03 will have on its consolidated financial statements. In September 2022, the FASB issued ASU 2022-04, Liabilities—Supplier Finance Programs (Subtopic 405-50): Disclosure of Supplier Finance Program Obligations. The ASU requires a buyer of goods and services to disclose information about its supplier finance program obligations. This ASU is effective for annual and interim periods in fiscal years beginning after December 15, 2022, except for the rollforward disclosure, which is effective for annual and interim periods in fiscal years beginning after December 15, 2023, and annual periods thereafter. The amendments in this ASU are to be applied retrospectively to each period in which a balance sheet is presented, except for the rollforward disclosure, which is to be applied prospectively. The adoption of ASU 2022-04 did not have a material effect on the consolidated financial statements. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures, which expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. The updated standard is effective for annual periods beginning in fiscal 2025 and interim periods beginning in the first quarter of fiscal 2026. Early adoption is permitted. The Company is currently evaluating the effect the adoption of ASU 2023-07 will have on its consolidated financial statements. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740) – Improvements to Income Tax Disclosures, which requires companies to disclose, on an annual basis, specific categories in the effective tax rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold. In addition, companies are required to disclose additional information about income taxes paid. The standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The standard is to be adopted on a prospective basis; however, retrospective application is permitted. The Company is currently evaluating the effect the adoption of ASU 2023-09 will have on its consolidated financial statements.

The Company and Summary of Si_3

The Company and Summary of Significant Accounting Policies (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Organization and Liquidity
Schedule of Potentially dilutive securities that were excluded from the computation of diluted net loss per common share	The following outstanding potentially dilutive common stock equivalents were excluded from the computation of diluted net income (loss) per share for the periods indicated because including them would have been antidilutive (in thousands): ​ ​ ​ ​ ​ ​ March 31, ​ ​ 2024 2023 Warrants 26,724 995 Convertible promissory notes 5,543 1,809 Options — 885 Total 32,267 3,689 ​	​ ​ ​ ​ ​ ​ ​ 2023 2022 Convertible promissory notes 9,827,666 9,688,740 Warrants 9,200,000 3,942,853 Options 3,579,294 4,773,892 Restricted Stock Units (RSU) 2,099,970 — Total 24,706,930 18,405,485
Schedule of disaggregation of revenues from contracts with customers and categorized by customer location	Disaggregation of revenues from contracts with customers is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2024 ​ Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ ​ At a point in time ​ $ 2,378 ​ $ — ​ $ 2,378 Over time ​ — ​ 887 ​ 887 Total ​ $ 2,378 ​ $ 887 ​ $ 3,265 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2023 ​ Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 599 ​ $ — ​ $ 599 Over time ​ — ​ 2,463 ​ 2,463 Total ​ $ 599 ​ $ 2,463 ​ $ 3,062 ​ Net revenues categorized by customer location are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ 2024 ​ 2023 Korea ​ $ 2,000 ​ $ — Germany ​ 796 ​ — United States ​ 389 ​ 1,968 China ​ 80 ​ 1,094 Total ​ $ 3,265 ​ $ 3,062	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2023 (in thousands) ​ Product Revenues ​ Service Revenues ​ Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 10,968 ​ $ — ​ $ 10,968 Over time ​ — ​ 5,060 ​ 5,060 Total ​ $ 10,968 ​ $ 5,060 ​ $ 16,028 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2022 (in thousands) Product Revenues Service Revenues Total Timing of revenue recognition ​ ​ ​ At a point in time ​ $ 12,977 ​ $ — ​ $ 12,977 Over time ​ — ​ 3,692 ​ 3,692 Total ​ $ 12,977 ​ $ 3,692 ​ $ 16,669 Net revenues categorized by customer location are as follows for the years ended December 31: ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues from external customers (in thousands) ​ 2023 ​ 2022 United States $ 5,056 $ 4,379 China ​ 4,745 ​ 5,608 Korea ​ 4,260 ​ 1,360 Germany ​ 1,422 ​ — Taiwan ​ 543 ​ 4,639 Other ​ 2 ​ 25 Singapore ​ — ​ 658 Total ​ $ 16,028 ​ $ 16,669
Schedule of contract assets and liabilities and net revenues recognized in relation to contract liabilities	Details of contract assets and liabilities is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 Contract assets ​ $ 4,313 ​ $ 3,439 Assets recognized for costs incurred to fulfill a contract (*) ​ 13 ​ 12 Contract liabilities ​ 35 ​ 48 (*) The balances are included in prepaid expenses and other current assets in the accompanying condensed consolidated balance sheets.	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ December 31, 2023 ​ December 31, 2022 Contract assets ​ $ 3,439 ​ $ 886 Assets recognized for costs incurred to fulfill a contract (*) ​ 12 ​ 39 Contract liabilities ​ 48 ​ 651 (*)- The balances are included in prepaid expenses and other current assets in the accompanying consolidated balance sheets.
Schedule of net revenues and gross accounts receivable concentration	Net revenues recognized in relation to contract liabilities are as follows as of the periods indicated (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 March 31, 2023 Net revenues recognized that were included in the contract liabilities balance at the beginning of the period ​ $ 12 ​ $ 650 ​	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) December 31, 2023 December 31, 2022 Net revenues recognized that were included in the contract liabilities balance at the beginning of the year ​ $ 651 ​ $ 766 Details of external customers, who contribute more than 10% of the Company’s net revenues and gross accounts receivable as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Revenues ​ Accounts Receivable (in thousands) ​ 2023 ​ 2022 ​ 2023 ​ 2022 Customer A $ * $ 4,639 $ * $ 1,228 Customer B ​ 3,031 ​ 2,979 ​ 1,755 ​ 590 Customer C ​ * ​ 1,712 ​ * ​ 1,400 Customer D ​ * ​ 1,670 ​ 661 ​ 687 Customer E ​ * ​ * ​ * ​ 610 Customer F ​ * ​ * ​ 1,250 ​ * Customer G ​ 3,000 ​ * ​ * ​ * Customer H ​ * ​ * ​ 938 ​ * *Less than 10%
Schedule of changes in provisions for product warranties		Details and changes in provisions for product warranties for the years ended December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Beginning balance ​ $ 64 ​ $ 106 Provision ​ 18 ​ — Adjustment to prior provisions ​ (27) ​ (42) Ending balance ​ $ 55 ​ $ 64
Schedule of foreign currency exchange gains and losses		​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Foreign currency gain, net ​ $ 265 ​ $ 181

Fair Value of Measurements (T_2

Fair Value of Measurements (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value of Measurements
Schedule of classifications of the financial instruments that are measured at fair value on a recurring basis	Fair value hierarchy classifications of the financial instruments that are measured at fair value on a recurring basis are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 10,317 ​ $ 10,317 Warrant liabilities ​ — ​ — ​ 10,584 ​ 10,584 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2023 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2022 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 31,166 ​ $ 31,166
Schedule of valuation techniques and inputs used in the fair value measurement	The table below presents valuation techniques and inputs used in the fair value measurement categorized within Level 3 of the fair value hierarchy (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation techniques Inputs March 31, 2024 December 31, 2023 Convertible promissory notes, current Discounted Cash Flow Model (“DCF”) Discount rate, risk-free rate, credit spread, contractual cash flows ​ $ 5,645 ​ $ — ​ ​ PWERM (“Probability-Weighted Expected Return Method”) ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 27,794 Convertible promissory notes, net of current Binomial Lattice Model (“BLM”) Stock price, volatility, remaining term, risk-free rate, credit spread ​ $ 4,672 ​ $ — ​ ​ PWERM ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 6,239 Warrant liabilities – private and public warrants Black Scholes Merton Model (“BSM”) or BLM Exercise price, term to expiration, volatility, risk-free rate ​ $ 9,150 ​ $ — Warrant liabilities - other ​ ​ ​ ​ $ 1,434 $ —	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Valuation techniques Inputs 2023 2022 Convertible promissory notes, current PWERM Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ 27,794 ​ $ 31,166 Convertible promissory notes, net of current ​ ​ ​ 6,239 ​ —
Schedule of changes in the fair value of the Company's Level 3 financial liabilities	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Convertible promissory notes fair value - beginning of period ​ $ 34,033 ​ $ 31,166 Change in fair value of convertible promissory notes ​ 1,203 ​ (549) Conversion of convertible promissory notes ​ (41,209) ​ — Borrowing of convertible promissory notes ​ 16,290 ​ — Convertible promissory notes fair value - end of period ​ $ 10,317 ​ $ 30,617 ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Warrant Liabilities Fair value - beginning of period ​ $ — ​ $ — Private and public warrants assumed at Closing ​ 5,958 ​ — Change in fair value of warrant liabilities ​ 4,626 ​ — Warrant Liabilities Fair value - end of period ​ $ 10,584 ​ $ —	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Fair value as of beginning of period ​ $ 31,166 ​ $ 56,996 Change in fair value of convertible promissory notes ​ 1,428 ​ 450 Conversion of convertible promissory notes ​ (61) ​ (33,140) Repayment of convertible promissory notes ​ (500) ​ (1,140) Transfer of convertible promissory notes to bank borrowings ​ — ​ (1,000) Borrowing of convertible promissory notes ​ 2,000 ​ 9,000 Fair value as of end of period ​ $ 34,033 ​ $ 31,166

Balance Sheet Components (Tab_2

Balance Sheet Components (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Balance Sheet Components
Schedule of Inventory	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Raw materials ​ $ 414 ​ $ 448 Work-in-process ​ 498 ​ 601 Finished goods ​ 872 ​ 437 Total inventory ​ $ 1,784 ​ $ 1,486	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Raw materials ​ $ 448 ​ $ 182 Work-in-process ​ 601 ​ 891 Finished goods ​ 437 ​ 2,407 ​ ​ $ 1,486 ​ $ 3,480
Schedule of Prepaid expenses and other assets	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Prepaid expenses ​ $ 3,345 ​ $ 433 Prepaid inventory ​ ​ 1,429 ​ ​ 279 Lease deposit ​ 413 ​ 434 Other receivables and current assets ​ 279 ​ 117 IPO expenses ​ — ​ 1,643 Prepaid expenses and other current assets ​ $ 5,466 ​ $ 2,906	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 IPO expenses ​ $ 1,643 ​ $ — Intellectual property rights ​ 761 ​ 861 Lease deposit ​ 554 ​ 555 Prepaid expenses ​ 433 ​ 799 Prepaid inventory ​ 279 ​ 1,310 Other receivables ​ 105 ​ 102 Costs incurred to fulfill a contract ​ 12 ​ 39 ​ ​ 3,787 ​ 3,666 Less: Non-current assets ​ (881) ​ (993) Prepaid expenses and other current assets ​ $ 2,906 ​ $ 2,673
Schedule of Property and equipment, net		​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Production equipment ​ $ 14,887 ​ $ 14,800 IT equipment ​ 1,127 ​ 1,212 Furniture and fixtures ​ 784 ​ 799 Leasehold improvements ​ 293 ​ 388 Fixed assets in process ​ — ​ 39 Total property and equipment ​ 17,091 ​ 17,238 Less: accumulated depreciation and amortization ​ (16,319) ​ (16,127) ​ ​ $ 772 ​ $ 1,111
Schedule of components of lease expense and other information related to leases		​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Operating lease expense ​ $ 772 ​ $ 733 Finance lease expense ​ ​ Amortization of right of use assets ​ 14 ​ 18 Interest on lease liabilities ​ 1 ​ 2 Total finance lease expense ​ 15 ​ 20 ​ ​ $ 787 ​ $ 753 ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Supplemental cash flow information: ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ Cash used in operations for operating leases ​ $ 766 ​ $ 770 ​ Cash used in operations for finance leases ​ 1 ​ 2 ​ Payments made on finance leases ​ 17 ​ 24 ​ ROU assets obtained in exchange for lease obligations: ​ ​ ​ Operating leases ​ 1,476 ​ 826 ​ Weighted average remaining lease term: ​ ​ ​ Operating leases ​ 2.25 years ​ 3.57 years ​ Finance leases ​ — ​ 0.90 years ​ Weighted average discount rate: ​ ​ ​ Operating leases ​ 4.66 % 4.00 % Finance leases ​ — ​ 9.70 %
Schedule of Maturities of lease liabilities under noncancellable leases		​ ​ ​ ​ ​ ​ Operating (in thousands) ​ leases 2024 ​ $ 743 2025 ​ 712 2026 ​ 169 Total undiscounted lease payments ​ 1,624 Less: imputed interest ​ (94) Total lease liabilities ​ $ 1,530
Schedule of Intangibles, net		​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Intellectual properties ​ $ 1,118 ​ $ 943 Intangible assets in process ​ — ​ 180 Total acquired intangibles ​ 1,118 ​ 1,123 Less: accumulated amortization ​ (873) ​ (451) ​ ​ $ 245 ​ $ 672
Schedule of Accrued and other current liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Payroll and related expenses ​ $ 9,830 ​ $ 9,880 Accrued payables ​ ​ 7,853 ​ ​ 6,319 Other taxes payable ​ ​ 3,399 ​ ​ 158 Current portion of interest payable ​ ​ 3,395 ​ ​ 6,915 Professional fees ​ 444 ​ 499 Royalty and license fee ​ 60 ​ 58 Product warranty ​ 64 ​ 55 Other ​ 107 ​ 72 Accrued and other current liabilities ​ $ 25,152 ​ $ 23,956 ​	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Payroll and related expenses ​ $ 10,038 ​ $ 6,635 Accrued payables ​ 6,319 ​ 2,233 Royalty and license fee ​ 58 ​ 37 Professional fees ​ 499 ​ 479 Current portion of interest payable ​ 6,915 ​ 2,944 Product warranty ​ 55 ​ 64 Other ​ 72 ​ 104 ​ ​ $ 23,956 ​ $ 12,496
Schedule of Other liabilities		​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Severance payments liability ​ $ 92 $ 76 Interest payable ​ 16 — ​ ​ $ 108 $ 76 ​

Debt (Tables)_2

Debt (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Borrowings
Schedule of borrowings	The Company’s outstanding debt was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 ​ ​ Principal ​ Fair Value ​ Principal ​ Fair Value Convertible promissory notes: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Historical convertible promissory notes ​ $ 5,630 ​ $ 5,645 ​ $ 35,347 ​ $ 34,033 2023 & 2024 convertible promissory notes ​ 5,000 ​ 4,672 ​ — ​ — Borrowings: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ KEB Hana Bank ​ 6,682 ​ 6,682 ​ 6,980 ​ 6,980 IBK Industrial Bank ​ 6,831 ​ 6,831 ​ 7,135 ​ 7,135 Note payable (one individual investor) ​ 1,000 ​ 1,000 ​ 1,000 ​ 1,000 M-Venture Investment, Inc. ​ 7,425 ​ 7,425 ​ 7,756 ​ 7,756 Anapass, Inc, related party ​ 9,653 ​ 9,653 ​ 10,082 ​ 10,082 i Best Investment Co., Ltd ​ 7,425 ​ 7,425 ​ 10,082 ​ 10,082 Kyeongho Lee, related party ​ 824 ​ 824 ​ 1,474 ​ 1,474 Total debt ​ $ 50,470 ​ 50,157 ​ $ 79,856 ​ 78,542 Less: current portion ​ ​ ​ ​ (45,485) ​ ​ ​ ​ (72,303) Debt, net of current portion ​ ​ ​ ​ $ 4,672 ​ ​ ​ ​ $ 6,239 ​	​ ​ ​ ​ ​ ​ ​ ​ ​ Category Creditor Maturity date Annual interest rate Korean Won KEB Hana Bank (*1) 7/12/2024 5.23 % Korean Won IBK Industrial Bank (*1) 11/20/2024 4.89 % Korean Won Anapass, Inc. 7/25/2024 5.50 % Korean Won Anapass, Inc. 5/10/2024 5.50 % Korean Won Anapass, Inc. 9/15/2024 5.50 % Korean Won Kyeongho Lee 11/19/2024 9.00 % Korean Won Kyeongho Lee 5/27/2024 0 % Korean Won Kyeongho Lee 11/24/2023 6.80 % Korean Won Kyeongho Lee 11/30/2024 7.50 % Korean Won Kyeongho Lee 12/2/2024 (*9) 7.50 % Korean Won M-Venture Investment, Inc. (*3) 10/29/2024 6.50 % Korean Won M-Venture Investment, Inc. (*4) 4/26/2024 6.50% - 8.65 %(*6) Korean Won i Best Investment Co., Ltd. (*5) 3/14/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. (*7) 12/22/2023 6.50 % Korean Won i Best Investment Co., Ltd. 3/12/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. 1/12/2024 (*9) 6.50 % Korean Won i Best Investment Co., Ltd. 3/14/2024 (*8) 6.50 % Korean Won i Best Investment Co., Ltd. 1/26/2024 (*2) 6.50 % Promissory Note One (1) individual investor 6/30/2024 4.00 % (*1) The limits for borrowings from KEB Hana Bank and IBK Industrial Bank are $6,980,000 and $7,135,000, respectively, and the bank deposit of Anapass, Inc., a related party, is pledged as collateral for borrowings from KEB Hana Bank and IBK Industrial Bank (see Notes 5 and 12). As of the current fiscal year end, collateral was provided to Anapass, Inc. in relation to the borrowings from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. (see Notes 5 and 12). (*2) Maturity date was extended for five (*3) (*4) (*5) (*6) (*7) (*8) three (*9) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ Category ​ Creditor ​ December 31, 2023 ​ December 31, 2022 Korean Won KEB Hana Bank (*1) ​ $ 6,980 ​ $ 7,102 Korean Won IBK Industrial Bank (*1) ​ 7,135 ​ 7,260 Korean Won Anapass, Inc. ​ 4,653 ​ 4,735 Korean Won Anapass, Inc. ​ 2,327 ​ 2,367 Korean Won Anapass, Inc. ​ 3,102 ​ 3,156 Korean Won Kyeongho Lee ​ 388 ​ 395 Korean Won Kyeongho Lee ​ 85 ​ 87 Korean Won Kyeongho Lee ​ — ​ 24 Korean Won Kyeongho Lee ​ 388 ​ 395 Korean Won Kyeongho Lee ​ 613 ​ 789 Korean Won M-Venture Investment, Inc. (*3) ​ 3,102 ​ 3,156 Korean Won M-Venture Investment, Inc.(*4) ​ 4,653 ​ 4,734 Korean Won i Best Investment Co., Ltd. (*5) ​ 3,102 ​ 3,156 Korean Won i Best Investment Co., Ltd. (*7) ​ — ​ — Korean Won i Best Investment Co., Ltd. ​ 1,551 ​ — Korean Won i Best Investment Co., Ltd. ​ 2,327 ​ — Korean Won i Best Investment Co., Ltd. ​ 2,327 ​ — Korean Won i Best Investment Co., Ltd. ​ 776 ​ — Promissory Note One (1) individual investor ​ 1,000 ​ 1,000 Bank Borrowings ​ $ 44,509 ​ $ 38,356
Schedule of maturities of borrowings	Expected future minimum principal payments under the Company’s total debt is as follows as of March 31, 2024 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible ​ ​ ​ ​ ​ ​ Notes ​ ​ ​ ​ ​ ​ Years ​ Payable ​ Borrowing ​ Total 2024, remainder ​ $ 5,630 ​ $ 39,840 ​ $ 45,470 2025 ​ — ​ — ​ — 2026 ​ 5,000 ​ — ​ 5,000 Total debt ​ $ 10,630 ​ $ 39,840 ​ $ 50,470
Schedule of convertible notes		​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Category ​ Creditor ​ December 31, 2023 ​ December 31, 2022 Current convertible notes (*1) ​ ​ 1st SG Ace Inc. (*2) ​ $ 7,620 ​ $ 8,461 2nd M-Venture Investment, Inc. and one (1) institution (*3) ​ 7,620 ​ 8,461 7th NA Korea Trans Fund No.4, one (1) institution and eight(8) individual investors (*4) ​ 2,198 ​ 1,932 16th NA Korea Trans Fund No.4 and two (2) individual investors ​ 387 ​ 330 22nd i Best Investment Co., Ltd. ​ 3,233 ​ 2,746 23rd Jeju Semiconductor Corp. ​ 908 ​ 771 24th One (1) individual investor ​ 665 ​ 565 25th M-Venture Investment Inc. (*5) ​ — ​ 3,511 26th Access Bio, Inc. ​ 5,163 ​ 4,389 ​ Subtotal ​ 27,794 ​ 31,166 Non-current convertible notes ​ ​ 25th M-Venture Investment Inc. (*5) ​ 3,614 ​ — 27th Blacktree Co., Ltd. ​ 2,625 ​ — ​ Subtotal ​ 6,239 ​ — ​ Total ​ $ 34,033 ​ $ 31,166 (*1) (*2) (*3) (*4) (*5)
Schedule of terms of issuance of convertible notes		Key terms for issuance of convertible notes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1st 2nd 7th 16th 22nd 23rd 24th 25th 26th 27th Issue Year ​ 2017 2017 2019 2020 2021 2021 2021 2022 2022 ​ 2023 Early repayment ​ (*1) (*1) (*2) (*1) (*1) (*1) (*1) (*2) (*3) ​ (*1) Repayment at maturity ​ The payment shall be made three years after the date of issue at an annual interest rate of 4% . The payment shall be made three years after the date of issue at an annual interest rate of 7% . The payment shall be made three years after the date of issue at an annual interest rate of 5% . The payment shall be made three years after the date of issue at an annual interest rate of 4% . ​ The payment shall be made three years after the date of issue at an annual interest rate of 5% . Rates applied at the repayment date ​ Upon repayment, there is a clause to reimburse the U.S. Dollar amount converted at the Won-Dollar exchange rate on the redemption date based on the Won amount converted at the Won-Dollar exchange rate at the date of issue. ​ N/A N/A N/A N/A N/A N/A ​ N/A Conversion price ​ $ 3.50 per share (*4) ​ ​ $ 6.67 per share ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1st 2nd 7th 16th 22nd 23rd 24th 25th 26th 27th Conversion - The holder of convertible notes can covert it at any time. ​ - If the Company issues a new equity instrument after issuing convertible notes, the holder of convertible notes may participate in conversion with the issuance price of the new equity instruments (1st, 2nd and 27th convertible notes) or $3.50 per share up to seven days prior to the issuance of the equity instruments. ​ - Conversion upon demand at holder’s discretion with conversion price equal to $3.50 ($6.67 for 27th convertible note) per share after issue date. ​ - Automatic conversion in an initial public offering (“IPO”) or business combination with SPAC (except for 1st and 24th convertible notes) (conversion price is adjusted to IPO price or SPAC conversion price). ​ - If the price at the time of issuance of a new equity instrument or the IPO is lower than $3.50, the conversion price of the convertible note is adjusted (except for 27th convertible note). ​ - Conversion price is adjusted every three months for one year after an IPO at KOSDAQ (However, adjusted price cannot be lower than 70% of $3.50 per share and cannot be higher than $3.50 per share) (7th convertible note). Number of convertible shares (*5) 5,142,858 shares ​ 553,790 shares 102,597 shares 874,286 shares 245,714 shares 180,000 shares 1,000,000 shares 1,428,571 shares 299,850 shares Collateral and guarantee (*6) ​ (*7) N/A (*8) N/A (*7) N/A (*7) N/A (*1) early repayment exercised once every quarter times in total for periods after from date issue convertible notes until from the date issue convertible notes (*2) times periods convertible convertible (*3) (*4) (*5) (*6) shares (*7) (*8)
Notes and loans payable
Borrowings
Schedule of maturities of borrowings		Maturities of borrowings as of December 31, 2023 were as follows: ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2024 ​ $ 44,509 Total ​ $ 44,509
Convertible debt
Borrowings
Schedule of maturities of borrowings		Maturities of convertible notes as of December 31, 2023, were as follows: ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2024 ​ $ 27,794 December 31, 2025 ​ 3,614 December 31, 2026 ​ 2,625 Total ​ $ 34,033

Commitments and Contingencies_4

Commitments and Contingencies (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies.
Schedule of collateral provided to Anapass, Inc	The following table includes a summary of the collateral provided to Anapass, Inc. (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, Secured ​ ​ 2024 ​ 2023 ​ Creditor Cash and cash equivalents ​ $ 16,122 ​ $ 254 ​ ​ Accounts receivable ​ ​ 5,118 ​ ​ 4,920 ​ Inventory ​ 1,784 ​ 1,486 Anapass, Inc. Property and equipment ​ 1,988 ​ 352 Intangible assets and others ​ 187 ​ 199 ​	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) December 31, December 31, Secured ​ ​ 2023 ​ 2022 ​ Creditor Cash and cash equivalents ​ $ 254 ​ $ 1,363 Accounts receivable ​ 4,920 ​ 4,453 Inventory ​ 1,486 ​ 3,480 Anapass, Inc. Property and equipment ​ 352 ​ 485 Intangible assets and others ​ 199 ​ 531 ​

Common Stock (Tables)_2

Common Stock (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Common Stock
Summary of shares reserved for shares authorized but unissued common stock	The Company has reserved shares of common stock for issuance as follows (in thousands): ​ ​ ​ ​ ​ ​ March 31 December 31 ​ ​ 2024 ​ 2023 Warrants ​ 26,724 ​ 2,894 Shares available for future grant from 2024 plan ​ 3,983 ​ — Convertible promissory notes 800 1,835 Options issued and outstanding 668 668 Shares available for future grant from 2024 ESPP 600 — RSUs outstanding 392 392 Shares available for future grant from 2011 plan — 113 Total 33,167 5,902 ​	The Company has reserved the following shares of authorized but unissued common stock as of December 31, 2023 ​ ​ ​ Options outstanding 3,579,294 RSUs outstanding 2,099,970 Shares available for grant from 2011 plan 605,826 Warrants 9,200,000 Convertible promissory notes 9,827,666 Total 25,312,756 ​

Warrants (Tables)_2

Warrants (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Warrants
Summary of warrants	The following table represents a summary of warrants to purchase shares of the Company’s common stock that are outstanding (in thousands, except for exercise price): ​ ​ ​ ​ ​ ​ ​ Issue Date March 31, 2024 Exercise Price Expiration August 2021 ​ 299 ​ $ 10.00 - $18.75 ​ (1) September 2021 300 ​ $ 5.00 (1) February 2023 - June 2023 2,115 ​ $ 10.00 - $18.75 (1) July 2023 80 ​ $ 10.00 (1) October 2023 100 ​ $ 10.00 (1) Private and public warrants 23,830 ​ $ 11.50 ​ March 26, 2029 Tota l 26,724 ​ ​ (1) Within 3 years from the date of issuance.	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Issued Exercised Expired/ Outstanding ​ ​ ​ ​ ​ ​ Cancelled ​ ​ December 2020 (*1) 2,514,285 — (2,514,285) — February 2021 (*2) 342,857 — (342,857) — August 2021 (*3) 999,997 — — 999,997 September 2021 (*3) 428,571 — — 428,571 February 2023 ~ June 2023 (*7) (*9) 7,685,717 (428,572) — 7,257,145 July 2023 (*7) 228,572 — — 228,572 October 2023 (*7) 285,715 — — 285,715 ​ ​ ​ ​ ​ ​ ​ ​ ​ Exercise Price Expiration December 2020 (*1) ​ $ 3.50 (*5) Earlier of within 2 years from the date of issuance or 2 weeks before U.S. IPO or Korea IPO February 2021 (*2) ​ $ 3.50 (*4) Within 18 months from the date of issuance August 2021 (*3) ​ $ 3.50 (*6) Within 3 years from the date of issuance September 2021 (*3) ​ $ 3.50 (*5) Within 3 years from the date of issuance February 2023 ~ June 2023 (*7) (*9) ​ $ 3.50 (*8) Within 3 years from the date of issuance July 2023 (*7) ​ $ 3.50 (*10) Within 3 years from the date of issuance October 2023 (*7) ​ $ 3.50 (*10) Within 3 years from the date of issuance (*1) (*2) (*3) (*4) (*5) (*6) (*7) (*8) (*9) (*10)

Stock-Based Compensation (Tab_2

Stock-Based Compensation (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Stock-Based Compensation
Summary of stock option activity	Stock options outstanding under the 2024 Plan were as follows (in thousands, except per share amounts and years): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Number of ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ Options ​ Average ​ Contractual Life ​ Aggregated ​ ​ Outstanding ​ Exercise Price ​ (in Years) ​ Intrinsic Value Balance as of December 31, 2023 ​ 3,579 ​ $ 0.02 ​ 5.5 ​ $ 4,405 Reverse recapitalization ​ (2,911) ​ ​ 0.09 ​ — ​ ​ — Balance as of December 31, 2023 (1) ​ 668 ​ ​ 0.11 ​ 5.5 ​ ​ 4,405 Granted ​ — ​ ​ — ​ — ​ ​ — Exercised ​ — ​ ​ — ​ — ​ ​ — Cancelled ​ — ​ ​ — ​ — ​ ​ — Balance as of March 31, 2024 668 $ 0.11 5.3 $ 5,543 Vested as of March 31, 2024 667 ​ $ 0.11 5.3 $ 5,532 Exercisable as of March 31, 2024 634 ​ $ 0.11 5.1 $ 5,256 (1) Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (see Note 3).	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Number of ​ ​ ​ ​ Average ​ ​ Shares ​ Stock ​ Weighted- ​ Remaining ​ ​ Available ​ Options ​ Average ​ Contractual Life ​ for Grant Outstanding Exercise Price (Years) Balances as of January 1, 2022 ​ 1,679,763 ​ ​ 8,194,822 ​ $ 0.02 ​ 6.1 Granted (105,000) ​ 105,000 ​ 0.02 Exercised — ​ (2,459,014) ​ 0.02 Cancelled 1,066,916 ​ (1,066,916) ​ 0.02 Balances as of December 31, 2022 2,641,679 ​ 4,773,892 ​ 0.02 5.1 RSUs granted (2,099,970) ​ — ​ — Exercised — ​ (1,130,481) ​ 0.02 Cancelled 64,117 ​ (64,117) ​ 0.02 Balances as of December 31, 2023 605,826 ​ 3,579,294 ​ 0.02 5.5 Vested as of December 31, 2023 ​ ​ ​ 3,311,859 ​ $ 0.02 ​ 5.3 Vested and expected to be vest as of December 31, 2023 ​ ​ ​ 3,569,024 ​ $ 0.02 ​ 5.5
Summary of assumptions used to calculate fair value of employee stock options		​ ​ ​ ​ ​ ​ 2022 Estimated term (in years) 5.8 ​ Risk-free interest rate 1.85 % Expected volatility 65 % Expected dividend yield 0 %
Summary of RSUs activity	RSUs outstanding under the 2024 Plan were as follows (in thousands, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of RSUs ​ Average Grant ​ ​ Outstanding ​ Date Fair Value Balance as of December 31, 2023 ​ 2,100 ​ $ 1.15 Reverse recapitalization ​ (1,708) ​ ​ 5.01 Balances as of December 31, 2023 (1) ​ 392 ​ $ 6.16 Granted — ​ — Vested — ​ — Cancelled — ​ — Balance as of March 31, 2024 392 ​ $ 6.16 (1) Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (see Note 3).	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of ​ Average Grant ​ Shares Date Fair Value Nonvested, outstanding at December 31, 2022 — ​ $ — Granted 2,099,970 ​ 1.15 Vested — ​ — Cancelled — ​ — Nonvested, outstanding at December 31, 2023 2,099,970 ​ $ 1.15

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Taxes
Schedule of domestic and foreign components of income (loss) before provision for income taxes	The domestic and foreign components of income (loss) before provision for income taxes were as follows for the years ended December 31: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Domestic ​ $ (19,910) ​ $ (30,559) Foreign ​ (2,018) ​ 4,268 Loss before provision for income taxes ​ $ (21,928) ​ $ (26,291)
Schedule of provision for income taxes	The provision for income taxes for the years ended December 31, 2023 and 2022 consisted of the following: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Current ​ ​ Federal ​ $ 215 ​ $ 128 State ​ 1 ​ 1 Foreign ​ 325 ​ (8) Total current ​ 541 ​ 121 ​ ​ ​ ​ ​ ​ ​ Deferred ​ ​ Federal ​ — ​ — State ​ — ​ — Foreign ​ — ​ — Total deferred ​ — ​ — Total provision for income taxes ​ $ 541 ​ $ 121
Schedule of reconciliation of federal statutory income tax to provision for income taxes	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Expected benefit at statutory federal rate ​ $ (4,941) ​ $ (6,717) State tax — net of federal benefit ​ 72 ​ 100 Research and development credits ​ — ​ (564) Foreign income/losses taxed at different rates ​ 14 ​ 15 Unrecognized tax benefits ​ 276 ​ 126 Stock-based compensation ​ 8 ​ 3 Interest expense ​ 333 ​ 233 Remeasurements of net defined benefit liabilities ​ 5 ​ — Exchange rate difference ​ 287 ​ 551 Change in tax rate ​ (242) ​ (92) True-up deferred taxes ​ 1,382 ​ 3,254 True-up payable ​ 75 ​ — Accumulated deficit ​ 67 ​ 10 Change in valuation allowance ​ 3,182 ​ 3,246 Other ​ 23 ​ (44) Total provision for income taxes ​ $ 541 ​ $ 121
Schedule of significant components of deferred tax assets and liabilities	​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Deferred tax assets ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 79,078 ​ $ 78,583 Capitalized costs ​ 5,409 ​ 3,095 Accruals and reserves ​ 4,610 ​ 4,830 Inventory reserves ​ 267 ​ 402 Stock compensation ​ 382 ​ 368 Loss on unrealized currency translation ​ 166 ​ 160 Research and development credits ​ 2,490 ​ 2,490 Financial guarantee liabilities ​ 5,410 ​ 5,320 Lease liability ​ 197 ​ 4 Provision for credit losses ​ 368 ​ 119 Gross deferred tax assets ​ 98,377 ​ 95,371 Valuation allowance ​ (97,628) ​ (94,446) Net deferred tax assets ​ 749 ​ 925 Deferred tax liabilities ​ ​ ​ ​ ​ ​ Revaluation of convertible promissory notes ​ (448) ​ (742) Contract assets ​ (3) ​ (8) ROU assets ​ (298) ​ (175) Gross deferred tax liabilities ​ (749) ​ (925) Net deferred income tax ​ $ — ​ $ —
Schedule of reconciliation of the unrecognized tax benefits ("UTBs")	A reconciliation of the unrecognized tax benefits (“UTBs”) as of December 31, 2023 and 2022 is as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Beginning gross UTBs ​ $ 3,203 ​ $ 3,106 Additions for tax positions taken in a prior year ​ — ​ (35) Additions for tax provision taken in the current year ​ 319 ​ 1,093 Adjustments for tax positions for changes in currency translation ​ 95 ​ (223) Reductions for tax positions taken in the prior year ​ 1,051 ​ (270) Reductions for tax positions taken in the prior year due to statutes lapsing ​ (1,585) ​ (468) Ending gross UTBs ​ 3,083 ​ 3,203 UTBs offset by deferred tax assets and/or valuation allowance ​ (1,419) ​ (1,714) Net UTBs ​ $ 1,664 ​ $ 1,489

Employee Benefit Plans (Table_2

Employee Benefit Plans (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Employee Benefit Plans
Summary of net liability for severance payments	The net liability for severance payments as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 Liability for severance payments, beginning ​ $ 7,764 ​ $ 7,997 Deposit ​ (276) ​ (308) Liability for severance payments, ending ​ $ 7,488 ​ $ 7,689 ​	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Liability for severance payments ​ $ 7,997 ​ $ 7,248 Deposit ​ (308) ​ (343) ​ ​ $ 7,689 ​ $ 6,905 ​

Related Party Transactions (T_2

Related Party Transactions (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Related Party Transactions
Summary of balances and transactions with the related parties	A summary of balances and transactions with the related parties who are stockholders of the Company were as follows as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 ​ ​ Anapass Kyeongho Lee ​ Anapass Kyeongho Lee Borrowings ​ $ 9,653 ​ $ 824 ​ $ 10,082 ​ $ 1,474 Other current liabilities ​ 106 ​ 87 ​ 212 ​ 182	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ 2023 ​ 2022 ​ Anapass Kyeongho Lee Anapass Kyeongho Lee Borrowings ​ $ 10,082 ​ $ 1,474 ​ $ 10,257 ​ $ 1,690 Other current liabilities ​ 212 ​ 182 ​ 11 ​ 150 Interest expense ​ 548 ​ 110 ​ 389 ​ 140 ​

Segments and Geographical Inf_2

Segments and Geographical Information (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Segments and Information
Summary of long-lived assets by geographic region	The Company operates in one segment. Revenue information by geographic region is presented in Note 4 to these condensed consolidated financial statements. Long-lived assets by geographic region were as follows as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 South Korea ​ $ 1,170 ​ $ 1,363 United States ​ 817 ​ 930 Total long-lived assets ​ $ 1,987 ​ $ 2,293 ​	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 United States ​ $ 930 ​ $ 1,295 South Korea ​ 1,363 ​ 626 Total long-lived assets ​ $ 2,293 ​ $ 1,921 ​

The Company and Summary of Si_4

The Company and Summary of Significant Accounting Policies (Details) - shares	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
The Company and Summary of Significant Accounting Policies
Potentially dilutive securities that were excluded from the computation of diluted net loss per common share	32,267,000	3,689,000	24,706,930	18,405,485
Convertible promissory notes
The Company and Summary of Significant Accounting Policies
Potentially dilutive securities that were excluded from the computation of diluted net loss per common share			9,827,666	9,688,740
Warrants
The Company and Summary of Significant Accounting Policies
Potentially dilutive securities that were excluded from the computation of diluted net loss per common share	26,724,000	995,000	9,200,000	3,942,853
Options issued and outstanding
The Company and Summary of Significant Accounting Policies
Potentially dilutive securities that were excluded from the computation of diluted net loss per common share		885,000	3,579,294	4,773,892
RSUs outstanding
The Company and Summary of Significant Accounting Policies
Potentially dilutive securities that were excluded from the computation of diluted net loss per common share			2,099,970

The Company and Summary of Si_5

The Company and Summary of Significant Accounting Policies - Going Concern, Liquidity and Management's Plan (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Organization and Liquidity
Accumulated deficit	$ (548,897)		$ (549,654)	$ (527,185)
Negative working capital			101,800
Net loss	757	$ (1,393)	(22,469)	(26,412)
Used cash from operations	$ (14,413)	$ (1,480)	$ (8,827)	$ (18,087)
Doubt about the Company's ability to continue as a going concern			true

The Company and Summary of Si_6

The Company and Summary of Significant Accounting Policies - Accounts Receivable and Provision for Credit Losses (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Organization and Liquidity
Provisions for credit losses	$ 1,900,000	$ 1,644,000	$ 549,000

The Company and Summary of Si_7

The Company and Summary of Significant Accounting Policies - Inventory (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Organization and Liquidity
Inventory written down	$ 0	$ 0	$ 358,000	$ 338,000

The Company and Summary of Si_8

The Company and Summary of Significant Accounting Policies - Property and Equipment, Net (Details)	Dec. 31, 2023
Minimum
The Company and Summary of Significant Accounting Policies
Estimated useful lives of plant and equipment	3 years
Maximum
The Company and Summary of Significant Accounting Policies
Estimated useful lives of plant and equipment	7 years

The Company and Summary of Si_9

The Company and Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	$ 3,265	$ 3,062	$ 16,028	$ 16,669
At a point in time
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	2,378	599	10,968	12,977
Over time
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	887	2,463	5,060	3,692
Product Revenues
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	2,378	599	10,968	12,977
Product Revenues | At a point in time
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	2,378	599	10,968	12,977
Service Revenues
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	887	2,463	5,060	3,692
Service Revenues | Over time
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	$ 887	$ 2,463	$ 5,060	$ 3,692

The Company and Summary of S_10

The Company and Summary of Significant Accounting Policies - Net revenues categorized by customer location (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	$ 3,265	$ 3,062	$ 16,028	$ 16,669
UNITED STATES
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	389	1,968	5,056	4,379
CHINA
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	80	$ 1,094	4,745	5,608
KOREA, REPUBLIC OF
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	2,000		4,260	1,360
Germany
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	$ 796		1,422
TAIWAN
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers			543	4,639
Other
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers			$ 2	25
SINGAPORE
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers				$ 658

The Company and Summary of S_11

The Company and Summary of Significant Accounting Policies - Contract assets and liabilities (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
The Company and Summary of Significant Accounting Policies
Contract assets	$ 4,313,000	$ 3,439,000	$ 3,439,000	$ 886,000	$ 661,000
Assets recognized for costs incurred to fulfill a contract (*)	13,000	12,000	12,000	39,000
Contract liabilities	35,000	48,000	48,000	651,000
Contract asset recognized			2,560,000	879,000
Revenues recognized that were included in the contract liabilities	$ 12,000	$ 650,000	651,000	766,000
Development services
The Company and Summary of Significant Accounting Policies
Contract asset recognized			0	650,000
Technical advice and maintenance services
The Company and Summary of Significant Accounting Policies
Contract asset recognized			$ 48,000	$ 0

The Company and Summary of S_12

The Company and Summary of Significant Accounting Policies - Concentration of Revenues and Accounts Receivable (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($) customer	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) customer	Dec. 31, 2022 USD ($) customer
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers	$ 3,265	$ 3,062	$ 16,028	$ 16,669
Customer A
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers				4,639
Accounts Receivable				1,228
Customer B
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers			3,031	2,979
Accounts Receivable			1,755	590
Customer C
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers				1,712
Accounts Receivable				1,400
Customer D
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers				1,670
Accounts Receivable			661	687
Customer E
The Company and Summary of Significant Accounting Policies
Accounts Receivable				$ 610
Customer F
The Company and Summary of Significant Accounting Policies
Accounts Receivable			1,250
Customer G
The Company and Summary of Significant Accounting Policies
Revenues from contracts with customers			3,000
Customer H
The Company and Summary of Significant Accounting Policies
Accounts Receivable			$ 938
Revenue
The Company and Summary of Significant Accounting Policies
Number of customers | customer			2	4
Revenue | Two customers
The Company and Summary of Significant Accounting Policies
Number of customers | customer	2
Revenue | Four customers
The Company and Summary of Significant Accounting Policies
Number of customers | customer			4
Revenue | Customer concentration | Two customers
The Company and Summary of Significant Accounting Policies
Concentration risk percentage			38%
Revenue | Customer concentration | Four customers
The Company and Summary of Significant Accounting Policies
Concentration risk percentage				66%
Revenue | Customer concentration | Customer A
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	61%		28%
Revenue | Customer concentration | Customer B
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	24%		28%
Revenue | Customer concentration | Customer C
The Company and Summary of Significant Accounting Policies
Concentration risk percentage			25%
Revenue | Customer concentration | Customer D
The Company and Summary of Significant Accounting Policies
Concentration risk percentage			10%
Accounts receivable
The Company and Summary of Significant Accounting Policies
Number of customers | customer			4	5
Accounts receivable | Four customers
The Company and Summary of Significant Accounting Policies
Number of customers | customer	4		4
Accounts receivable | Customer concentration | Four customers
The Company and Summary of Significant Accounting Policies
Concentration risk percentage			70%
Accounts receivable | Customer concentration | Five customers
The Company and Summary of Significant Accounting Policies
Concentration risk percentage				90%
Accounts receivable | Customer concentration | Customer A
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	28%		27%
Accounts receivable | Customer concentration | Customer B
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	19%		19%
Accounts receivable | Customer concentration | Customer C
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	18%		14%
Accounts receivable | Customer concentration | Customer D
The Company and Summary of Significant Accounting Policies
Concentration risk percentage	13%		10%

The Company and Summary of S_13

The Company and Summary of Significant Accounting Policies - Warranty (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
changes in provisions for product warranties
Beginning balance	$ 64,000	$ 106,000
Provision	18,000
Adjustment to prior provisions	(27,000)	(42,000)
Ending balance	$ 55,000	$ 64,000

The Company and Summary of S_14

The Company and Summary of Significant Accounting Policies - Stock-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2023
RSUs
The Company and Summary of Significant Accounting Policies
Vesting period	4 years

The Company and Summary of S_15

The Company and Summary of Significant Accounting Policies - Foreign Currency Translation (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Organization and Liquidity
Foreign currency gain, net	$ 1,100	$ 700	$ 265	$ 181

Fair Value of Measurements (D_2

Fair Value of Measurements (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Fair Value of Measurements
Convertible promissory notes	$ 10,317	$ 34,033	$ 31,166
Fair Value, Inputs, Level 3 [Member]
Fair Value of Measurements
Convertible promissory notes	$ 10,317	$ 34,033	$ 31,166

Fair Value of Measurements - _2

Fair Value of Measurements - Valuation techniques and inputs (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value of Measurements
Convertible promissory notes, current	$ 27,794	$ 31,166
Convertible promissory notes, net of current	$ 6,239

Fair Value of Measurements - _3

Fair Value of Measurements - Changes in the fair value (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended		24 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023
Fair Value of Measurements
Change in fair value of convertible promissory notes, Extensible list	Other income (expense), net	Other income (expense), net			Interest to pay dissolution expenses
Convertible Debt [Member]
Fair Value of Measurements
Fair value as of beginning of period	$ 34,033	$ 31,166	$ 31,166	$ 56,996	$ 56,996
Change in fair value of convertible promissory notes	1,203	(549)	1,428	450
Conversion of convertible promissory notes			(61)	(33,140)
Repayment of convertible promissory notes			(500)	(1,140)
Transfer of convertible promissory notes to bank borrowings				(1,000)
Borrowing of convertible promissory notes	16,290		2,000	9,000
Fair value as of end of period	$ 10,317	$ 30,617	$ 34,033	$ 31,166	$ 34,033

Balance Sheet Components - In_2

Balance Sheet Components - Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Inventory
Raw materials	$ 414	$ 448	$ 182
Work-in-process	498	601	891
Finished goods	872	437	2,407
Total inventory	$ 1,784	$ 1,486	$ 3,480

Balance Sheet Components - Pr_2

Balance Sheet Components - Prepaid expenses and other assets (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Balance Sheet Components
IPO expenses		$ 1,643
Intellectual property rights		761		$ 861
Lease deposit	$ 413	554		555
Prepaid expenses		433		799
Prepaid inventory		279		1,310
Other receivables		105		102
Assets recognized for costs incurred to fulfill a contract (*)	13	12	$ 12	39
Total		3,787		3,666
Less: Non-current assets		(881)		(993)
Prepaid expenses and other current assets	$ 5,466	$ 2,906		$ 2,673

Balance Sheet Components - Prop

Balance Sheet Components - Property and equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2024
The Company and Summary of Significant Accounting Policies
Total property and equipment	$ 17,091	$ 17,238
Less: accumulated depreciation and amortization	(16,319)	(16,127)
Property and equipment, net	772	1,111	$ 644
Depreciation expense	640,000	518,000
Production equipment
The Company and Summary of Significant Accounting Policies
Total property and equipment	14,887	14,800
IT equipment
The Company and Summary of Significant Accounting Policies
Total property and equipment	1,127	1,212
Furniture and fixtures
The Company and Summary of Significant Accounting Policies
Total property and equipment	784	799
Leasehold improvements
The Company and Summary of Significant Accounting Policies
Total property and equipment	$ 293	388
Fixed assets in process
The Company and Summary of Significant Accounting Policies
Total property and equipment		$ 39

Balance Sheet Components - Leas

Balance Sheet Components - Leases (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Leases
Expiration term (in years)		4 years
Components of lease expense
Operating lease expense		$ 772	$ 733
Finance lease expense
Finance lease right-of-use amortization	$ 4	14	18
Interest on lease liabilities		1	2
Total finance lease expense		15	20
Total Operating and Finance lease expense		787	753
Cash Paid For Amounts Included In The Measurement Of Lease Liabilities
Cash used in operations for operating leases		766	770
Cash used in operations for finance leases		1	2
Payments made on finance leases		17	24
ROU assets obtained in exchange for lease obligations:
Operating leases		$ 1,476	$ 826
Weighted average remaining lease term:
Operating leases		2 years 3 months	3 years 6 months 25 days
Finance leases			10 months 24 days
Weighted average discount rate:
Operating leases		4.66%	4%
Finance leases			9.70%
Maturities of lease liabilities under noncancellable leases
2024		$ 743
2025		712
2026		169
Total undiscounted lease payments		1,624
Less: imputed interest		(94)
Total lease liabilities		$ 1,530
Minimum
Leases
Renewal term (in years)		2 years
Maximum
Leases
Renewal term (in years)		4 years

Balance Sheet Components - Inta

Balance Sheet Components - Intangibles, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2024
Intangibles, net
Total acquired intangibles	$ 1,118	$ 1,123
Less: accumulated amortization	(873)	(451)
Intangibles, net	245	672	$ 187
Amortization expense	422,000	147,000
Intellectual properties
Intangibles, net
Total acquired intangibles	$ 1,118	943
Intangible assets in process
Intangibles, net
Total acquired intangibles		$ 180

Balance Sheet Components - Ac_2

Balance Sheet Components - Accrued and other current liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Components
Payroll and related expenses	$ 9,830	$ 10,038	$ 6,635
Accrued payables	7,853	6,319	2,233
Royalty and license fee	60	58	37
Professional fees	444	499	479
Current portion of interest payable	3,395	6,915	2,944
Product warranty	64	55	64
Other	107	72	104
Total	$ 25,152	$ 23,956	$ 12,496

Balance Sheet Components - Othe

Balance Sheet Components - Other liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Components
Severance payments liability		$ 92	$ 76
Interest payable		16
Total	$ 72	$ 108	$ 76

Debt - Schedule of borrowings (

Debt - Schedule of borrowings (Details) ₩ in Billions		12 Months Ended
	Apr. 26, 2023 KRW (₩)	Dec. 31, 2023 USD ($) shares	Mar. 22, 2023 KRW (₩)	Dec. 31, 2022 USD ($)
Borrowings
Bank Borrowings		$ 44,509,000		$ 38,356,000
KEB Hana Bank | Related party
Borrowings
Bank Borrowings		6,980,000
IBK Industrial Bank | Related party
Borrowings
Bank Borrowings		$ 7,135,000
M-Venture Investment, Inc. | Kyeongho Lee
Borrowings
Collateral, number of shares | shares		170,000
i Best Investment Co., Ltd.
Borrowings
Limit for borrowings | ₩			₩ 1
i Best Investment Co., Ltd. | Kyeongho Lee
Borrowings
Collateral, number of shares | shares		40,000
Korean won borrowing maturity July 12, 2024 | KEB Hana Bank
Borrowings
Annual interest rate		5.23%
Bank Borrowings		$ 6,980,000		7,102,000
Korean won borrowing maturity November 20, 2024 | IBK Industrial Bank
Borrowings
Annual interest rate		4.89%
Bank Borrowings		$ 7,135,000		7,260,000
Korean won borrowing maturity July 25, 2024 | Anapass, Inc.
Borrowings
Annual interest rate		5.50%
Bank Borrowings		$ 4,653,000		4,735,000
Korean won borrowing maturity May 10, 2024 | Anapass, Inc.
Borrowings
Annual interest rate		5.50%
Bank Borrowings		$ 2,327,000		2,367,000
Korean won borrowing maturity September 15, 2024 | Anapass, Inc.
Borrowings
Annual interest rate		5.50%
Bank Borrowings		$ 3,102,000		3,156,000
Korean won borrowing maturity November 19, 2024 | Kyeongho Lee
Borrowings
Annual interest rate		9%
Bank Borrowings		$ 388,000		395,000
Korean won borrowing maturity May 27, 2024 | Kyeongho Lee
Borrowings
Annual interest rate		0%
Bank Borrowings		$ 85,000		87,000
Korean won borrowing maturity November 24, 2023 | Kyeongho Lee
Borrowings
Annual interest rate		6.80%
Bank Borrowings				24,000
Korean won borrowing maturity November 30, 2024 | Kyeongho Lee
Borrowings
Annual interest rate		7.50%
Bank Borrowings		$ 388,000		395,000
Korean won borrowing maturity December 2, 2024 | Kyeongho Lee
Borrowings
Annual interest rate		7.50%
Bank Borrowings		$ 613,000		789,000
Korean won borrowing maturity October 29, 2024 | M-Venture Investment, Inc.
Borrowings
Annual interest rate		6.50%
Bank Borrowings		$ 3,102,000		3,156,000
Korean won borrowing maturity April 26, 2024 | M-Venture Investment, Inc.
Borrowings
Bank Borrowings		$ 4,653,000		4,734,000
Korean won borrowing, 1.0 billion, maturity April 26, 2024
Borrowings
Annual interest rate	6.50%
Principal amount | ₩	₩ 1
Korean won borrowing, 1.0 billion, maturity April 26, 2024 | M-Venture Investment, Inc.
Borrowings
Annual interest rate		6.50%
Korean won borrowing, 5.0 billion, maturity April 26, 2024
Borrowings
Annual interest rate	8.65%
Principal amount | ₩	₩ 5
Korean won borrowing, 5.0 billion, maturity April 26, 2024 | M-Venture Investment, Inc.
Borrowings
Annual interest rate		8.65%
Korean won borrowing maturity December 22, 2023 | i Best Investment Co., Ltd.
Borrowings
Annual interest rate		6.50%
Korean won borrowing maturity March 12, 2024
Borrowings
Maturity term extension		3 months
Korean won borrowing maturity March 12, 2024 | i Best Investment Co., Ltd.
Borrowings
Annual interest rate		6.50%
Bank Borrowings		$ 1,551,000
Korean won borrowing maturity January 12, 2024 | i Best Investment Co., Ltd.
Borrowings
Annual interest rate		6.50%
Bank Borrowings		$ 2,327,000
Korean won borrowing maturity March 14, 2024 | i Best Investment Co., Ltd.
Borrowings
Annual interest rate		6.50%
Bank Borrowings		$ 3,102,000		3,156,000
Korean won borrowing maturity March 14, 2024 | i Best Investment Co., Ltd.
Borrowings
Bank Borrowings		$ 2,327,000
Korean won borrowing maturity January 26, 2024
Borrowings
Maturity term extension		5 months
Korean won borrowing maturity January 26, 2024 | i Best Investment Co., Ltd.
Borrowings
Annual interest rate		6.50%
Bank Borrowings		$ 776,000
Promissory note maturity June 30, 2024 | Individual investor
Borrowings
Annual interest rate		4%
Bank Borrowings		$ 1,000,000		$ 1,000,000

Debt - Maturities of borrowings

Debt - Maturities of borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Maturities of borrowings
December 31, 2024	$ 0
Total	$ 50,470	$ 79,856
Notes and loans payable
Maturities of borrowings
December 31, 2024		44,509
Total		$ 44,509

Debt - Schedule of convertible

Debt - Schedule of convertible notes (Details)					12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) item shares	Mar. 29, 2024 USD ($)	Jan. 31, 2024 USD ($)
Borrowings
Convertible notes, current	$ 27,794,000				$ 27,794,000	$ 31,166,000
Convertible notes, non-current	6,239,000				6,239,000
Convertible notes	34,033,000				$ 34,033,000	31,166,000
Amount of debt converted						32,500,000
Amount of unpaid interest converted						$ 2,600,000
Number of shares issued on conversion of debt | shares						10,026,354
SG Ace Inc
Borrowings
Debt installments	4,000,000	$ 4,000,000	$ 3,000,000	$ 2,000,000
Interest rate (as a percent)		7.50%	6.50%	5.50%
Default interest rate (as a percent)					12%
SG Ace Inc | Subsequent event
Borrowings
Principal amount							$ 9,000,000
NA Korea Trans Fund No.4, one (1) institution and eight(8) individual investors
Borrowings
Convertible notes	61,000				$ 61,000
Amount of unpaid interest converted					$ 11,000
Number of shares issued on conversion of debt | shares					20,681
i Best Investment Co., Ltd. | Subsequent event
Borrowings
Principal amount								$ 776,000
M-Venture Investment, Inc.
Borrowings
Convertible debt transferred					$ 500,000
GNI Partners Co., Ltd
Borrowings
Convertible notes						$ 708,000
Number of shares issued on conversion of debt | shares						202,168
1st convertible note | SG Ace Inc
Borrowings
Convertible notes, current	7,620,000				7,620,000	$ 8,461,000
2nd convertible note | M-Venture Investment, Inc. and one (1) institution
Borrowings
Convertible notes, current	7,620,000				7,620,000	8,461,000
7th convertible note | NA Korea Trans Fund No.4, one (1) institution and eight(8) individual investors
Borrowings
Convertible notes, current	2,198,000				2,198,000	1,932,000
16th convertible note | NA Korea Trans Fund No.4 and two (2) individual investors
Borrowings
Convertible notes, current	387,000				387,000	330,000
22nd convertible note | i Best Investment Co., Ltd.
Borrowings
Convertible notes, current	3,233,000				3,233,000	2,746,000
23rd convertible note | Jeju Semiconductor Corp.
Borrowings
Convertible notes, current	908,000				908,000	771,000
24th convertible note | Individual investor
Borrowings
Convertible notes, current	665,000				665,000	565,000
25th convertible note | M-Venture Investment, Inc.
Borrowings
Convertible notes, current						3,511,000
Convertible notes, non-current	3,614,000				3,614,000
26th convertible note | Access Bio, Inc
Borrowings
Convertible notes, current	5,163,000				5,163,000	4,389,000
27th convertible note | Blacktree Co., Ltd
Borrowings
Convertible notes, non-current	$ 2,625,000				$ 2,625,000
8th convertible note
Borrowings
Convertible notes						740,000
9th convertible note
Borrowings
Convertible notes						100,000
12th convertible note
Borrowings
Convertible notes						340,000
21st convertible note
Borrowings
Convertible notes						$ 1,000,000
Number of individual investors exercised early redemption | item						1

Debt - Maturities of convertibl

Debt - Maturities of convertible notes (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Maturities of convertible notes
December 31, 2024	$ 0
December 31, 2025	5,000
Total	$ 50,470	$ 79,856
Convertible debt
Maturities of convertible notes
December 31, 2024		27,794
December 31, 2025		3,614
December 31, 2026		2,625
Total		$ 34,033

Debt - Key terms of issuance of

Debt - Key terms of issuance of convertible notes (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) item EquityInstruments $ / shares shares	Dec. 31, 2022 USD ($) item EquityInstruments	Dec. 31, 2021 USD ($) item EquityInstruments	Dec. 31, 2020 item EquityInstruments	Dec. 31, 2019 item EquityInstruments	Dec. 31, 2017 EquityInstruments item $ / shares shares
Borrowings
Conversion price | $ / shares	$ 3.50
Conversion price adjustment occurrence period	3 months
Conversion price adjustment period	1 year
Conversion price adjustment as percent of threshold price	70%
Gain on fair value adjustment of convertible note financial liabilities | $	$ 2,619,000,000	$ 2,673,000,000
Loss on fair value adjustment of convertible note financial liabilities | $	$ 4,047,000,000	$ 3,123,000,000
Minimum
Borrowings
Conversion price | $ / shares	$ 3.50
Conversion price adjustment as percent of threshold price	70%
Maximum
Borrowings
Threshold conversion price | $ / shares	$ 3.50
i Best Investment Co., Ltd. | Kyeongho Lee
Borrowings
Collateral, number of shares | shares	40,000
M-Venture Investment, Inc. | Kyeongho Lee
Borrowings
Collateral, number of shares | shares	170,000
1st convertible note | SG Ace Inc
Borrowings
Early repayment exercise, number of times | item						4
Early repayment exercise period						7 days
Early repayment commencement after issue of convertible notes						2 years
Early repayment exercisable period						3 years
Debt maturity term						3 years
Annual interest rate						4%
Conversion price | $ / shares						$ 3.50
Debt instrument conversion price prior to issuance of equity instruments | $ / shares						$ 3.50
Debt conversion, period prior to issuance of equity instruments						7 days
Number of convertible shares | EquityInstruments						5,142,858
1st convertible note | SG Ace Inc | Kyeongho Lee | Related party
Borrowings
Collateral, number of shares | shares						885,867
2nd convertible note | M-Venture Investment, Inc. and one (1) institution
Borrowings
Early repayment exercise, number of times | item						4
Early repayment exercise period						7 days
Early repayment commencement after issue of convertible notes						2 years
Early repayment exercisable period						3 years
Debt maturity term						3 years
Annual interest rate						4%
Debt instrument conversion price prior to issuance of equity instruments | $ / shares						$ 3.50
Debt conversion, period prior to issuance of equity instruments						7 days
Number of convertible shares | EquityInstruments						5,142,858
2nd convertible note | M-Venture Investment, Inc. and one (1) institution | Kyeongho Lee | Related party
Borrowings
Collateral, number of shares | shares						885,867
7th convertible note | NA Korea Trans Fund No.4, one (1) institution and eight(8) individual investors
Borrowings
Early repayment exercise, number of times | item					4
Early repayment exercise period					7 days
Early repayment commencement after issue of convertible notes					1 year
Early repayment exercisable period					2 years
Debt maturity term					3 years
Annual interest rate					4%
Number of convertible shares | EquityInstruments					553,790
16th convertible note | NA Korea Trans Fund No.4 and two (2) individual investors
Borrowings
Early repayment exercise, number of times | item				4
Early repayment exercise period				7 days
Early repayment commencement after issue of convertible notes				2 years
Early repayment exercisable period				3 years
Debt maturity term				3 years
Annual interest rate				4%
Number of convertible shares | EquityInstruments				102,597
22nd convertible note | i Best Investment Co., Ltd.
Borrowings
Early repayment exercise, number of times | item			4
Early repayment exercise period			7 days
Early repayment commencement after issue of convertible notes			2 years
Early repayment exercisable period			3 years
Debt maturity term			3 years
Annual interest rate			4%
Number of convertible shares | EquityInstruments			874,286
22nd convertible note | i Best Investment Co., Ltd. | Kyeongho Lee | Related party
Borrowings
Collateral, number of shares | shares	175,000
23rd convertible note | Jeju Semiconductor Corp.
Borrowings
Early repayment exercise, number of times | item			4
Early repayment exercise period			7 days
Early repayment commencement after issue of convertible notes			2 years
Early repayment exercisable period			3 years
Debt maturity term			3 years
Annual interest rate			4%
Number of convertible shares | EquityInstruments			245,714
24th convertible note | Individual investor
Borrowings
Early repayment exercise, number of times | item			4
Early repayment exercise period			7 days
Early repayment commencement after issue of convertible notes			2 years
Early repayment exercisable period			3 years
Debt maturity term			3 years
Annual interest rate			7%
Number of convertible shares | EquityInstruments			180,000
25th convertible note | M-Venture Investment, Inc.
Borrowings
Early repayment exercise, number of times | item		4
Early repayment exercise period		7 years
Early repayment commencement after issue of convertible notes		1 year
Early repayment exercisable period		2 years
Debt maturity term		3 years
Annual interest rate		5%
Number of convertible shares | EquityInstruments		1,000,000
26th convertible note | Access Bio, Inc
Borrowings
Early repayment exercise, number of times | item		8
Early repayment exercise period		7 days
Early repayment commencement after issue of convertible notes		1 year
Early repayment exercisable period		3 years
Debt maturity term		3 years
Annual interest rate		4%
Number of convertible shares | EquityInstruments		1,428,571
27th convertible note | Blacktree Co., Ltd
Borrowings
Early repayment exercise, number of times | item	4
Early repayment exercise period	7 days
Early repayment commencement after issue of convertible notes	2 years
Early repayment exercisable period	3 years
Debt maturity term	3 years
Annual interest rate	5%
Conversion price | $ / shares	$ 6.67
Debt instrument conversion price prior to issuance of equity instruments | $ / shares	$ 3.50
Debt conversion, period prior to issuance of equity instruments	7 days
Number of convertible shares | EquityInstruments	299,850
5th convertible note | Amber International Ltd
Borrowings
Principal amount | $			$ 708,000

Commitments and Contingencies_5

Commitments and Contingencies - Purchase Commitment (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Purchase Commitment
Research and development expense	$ 5,521	$ 902	$ 10,712	$ 17,385
Unpaid recorded expenses included in accounts payable	1,242		17,814	19,017
Research and development agreement with Samsung
Purchase Commitment
Outstanding purchase commitments	0		0	500
Total fee amount	21,100		21,100
Fee amount to be paid over development milestones	11,700		11,700
Additional NRE to be paid as fee amount	$ 9,400		$ 9,400
Period for payment of additional NRE	4 years		4 years
Research and development expense			$ 400	7,100
Unpaid recorded expenses included in accounts payable			15,800	$ 15,400
Aggregated unpaid amount			$ 17,100

Commitments and Contingencies_6

Commitments and Contingencies - Assets Pledged as Collateral (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Borrowings
Borrowings	$ 50,470	$ 79,856
Cash and cash equivalents	16,122	258	$ 1,398
Accounts receivable	5,103	4,920	4,453
Inventory	1,784	1,486	3,480
Property and equipment	644	772	1,111
KEB Hana Bank | Related party | Assets pledged as collateral | Borrowings
Borrowings
Borrowings	6,700	7,000	7,100
IBK Industrial Bank | Related party | Assets pledged as collateral | Borrowings
Borrowings
Borrowings	6,800	7,100	7,300
Anapass, Inc. | Related party | Assets pledged as collateral | Borrowings
Borrowings
Borrowings	9,700	10,100	10,300
Cash and cash equivalents	16,122	254	1,363
Accounts receivable	5,118	4,920	4,453
Inventory	1,784	1,486	3,480
Property and equipment	1,988	352	485
Intangible assets and others	$ 187	$ 199	$ 531

Common Stock (Details)_2

Common Stock (Details) - $ / shares	Mar. 31, 2024	Mar. 26, 2024	Dec. 31, 2023	Dec. 31, 2022
Common Stock
Common stock, shares authorized	400,000,000		200,000,000	200,000,000
Common stock, shares issued	45,833,000	45,833,000	24,166,000	127,760,265
Common stock, par value per share	$ 0.0001		$ 0.0001	$ 0.0001

Common Stock - Shares authori_2

Common Stock - Shares authorized (Details) - shares	Mar. 31, 2024	Dec. 31, 2023
Common Stock
Shares of authorized but unissued common stock	33,167,000	5,902,000
Stock Options
Common Stock
Shares of authorized but unissued common stock	668,000	668,000
RSUs
Common Stock
Shares of authorized but unissued common stock	392,000	392,000
Shares available for grant from 2011 plan
Common Stock
Shares of authorized but unissued common stock		113,000
Warrants
Common Stock
Shares of authorized but unissued common stock	26,724,000	2,894,000
Convertible promissory notes
Common Stock
Shares of authorized but unissued common stock	800,000	1,835,000

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 27, 2022	Dec. 31, 2023	Dec. 31, 2022
Redeemable Convertible Preferred Stock
Common stock dividends issued to redeemable convertible preferred stock			28,685,582
Threshold term for occurrence of IPO for automatically conversion back into the applicable series of redeemable convertible preferred stock	2 years
Accretion of Series G redeemable convertible preferred stock to redemption amount		$ 0	$ 2,237

Warrants (Details)_2

Warrants (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Warrants
Number of warrants issued	26,724,000
Number of warrants exercised		428,572
Number of warrants outstanding		9,200,000
Warrants expiration term	3 years
December 2020
Warrants
Number of warrants issued		2,514,285
Number of warrants expired/ cancelled		(2,514,285)
Exercise price of warrants		$ 3.50
Warrants expiration term		2 years
February 2021
Warrants
Number of warrants issued		342,857
Number of warrants expired/ cancelled		(342,857)
Exercise price of warrants		$ 3.50
Warrants expiration term		18 months
August 2021
Warrants
Number of warrants issued	299,000	999,997
Number of warrants outstanding		999,997
Exercise price of warrants		$ 3.50
Warrants expiration term		3 years
September 2021
Warrants
Number of warrants issued	300,000	428,571
Number of warrants outstanding		428,571
Exercise price of warrants	$ 5	$ 3.50
Warrants expiration term		3 years
February 2023 ~ June 2023
Warrants
Number of warrants issued	2,115,000	7,685,717
Number of warrants exercised		(428,572)
Number of warrants outstanding		7,257,145
Exercise price of warrants		$ 3.50
Warrants expiration term		3 years
July 2023
Warrants
Number of warrants issued	80,000	228,572
Number of warrants outstanding		228,572
Exercise price of warrants	$ 10	$ 3.50
Warrants expiration term		3 years
October 2023
Warrants
Number of warrants issued	100,000	285,715
Number of warrants outstanding		285,715
Exercise price of warrants	$ 10	$ 3.50
Warrants expiration term		3 years

Warrants - Additional details (

Warrants - Additional details (Details)	1 Months Ended	12 Months Ended
	Oct. 31, 2023 $ / shares shares	Dec. 31, 2023 Lender shares
Warrants
Threshold percentage of price in the IPO for adjustment in exercise price		50%
De-SPAC IPO shares issued		685,713
Number of term loan lenders to whom warrants are issued | Lender		5
Number of warrants exercised		428,572
Number of warrants outstanding		9,200,000
Mujin Electronics Co., Ltd.
Warrants
Number of warrants exercised	428,572
Exercise price of warrants | $ / shares	$ 3.50

Stock-Based Compensation (Det_2

Stock-Based Compensation (Details) - shares	1 Months Ended
	Sep. 30, 2011	Mar. 31, 2024
Stock-Based Compensation
Number of shares of common stock reserved for issuance	6,277,777
Additional shares of common stock reserved for issuance	265,597	90,000
Increase in shares reserved for issuance as percentage of total number of shares of common stock outstanding	5%
Maximum annual increase	2,500,000

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock option activities (Details) - $ / shares	3 Months Ended	12 Months Ended			15 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2024
Number of Stock Options Outstanding
Balances as of beginning	392
Balances as of end	392	392			392
Weighted-Average Exercise Price
Balances as of beginning (in dollars per share)	$ 6.16
Balances as of end (in dollars per share)	$ 6.16	$ 6.16			$ 6.16
Stock Options
Shares Available for Grant
Balances as of beginning	605,826	2,641,679	1,679,763		2,641,679
Options granted		0	(105,000)		0
Cancelled		64,117	1,066,916
Balances as of end		605,826	2,641,679	1,679,763
Number of Stock Options Outstanding
Balances as of beginning	3,579,294	4,773,892	8,194,822		4,773,892
Granted		0	105,000		0
Exercised		(1,130,481)	(2,459,014)
Cancelled		(64,117)	(1,066,916)
Balances as of end	668,000	3,579,294	4,773,892	8,194,822	668,000
Vested as of end	667,000	3,311,859			667,000
Vested and expected to be vest as of end	634,000	3,569,024			634,000
Weighted-Average Exercise Price
Balances as of beginning (in dollars per share)	$ 0.02	$ 0.02	$ 0.02		$ 0.02
Granted (in dollars per share)			0.02
Exercised (in dollars per share)		0.02	0.02
Cancelled (in dollars per share)		0.02	0.02
Balances as of end (in dollars per share)	0.11	0.02	$ 0.02	$ 0.02	0.11
Vested as of end (in dollars per share)	0.11	0.02			0.11
Vested and expected to be vest as of end (in dollars per share)	$ 0.11	$ 0.02			$ 0.11
Weighted Average Remaining Contractual Life (Years)
Options Outstanding Weighted Average Remaining Contractual Life	5 years 3 months 18 days	5 years 6 months	5 years 1 month 6 days	6 years 1 month 6 days
Vested as of December 31, 2023	5 years 3 months 18 days	5 years 3 months 18 days
Vested and expected to be vest as of December 31, 2023	5 years 1 month 6 days	5 years 6 months
RSUs
Shares Available for Grant
RSUs granted		(2,099,970)
Number of Stock Options Outstanding
Balances as of beginning	2,100
Balances as of end		2,100
Weighted-Average Exercise Price
Balances as of beginning (in dollars per share)	$ 1.15
Balances as of end (in dollars per share)		$ 1.15

Stock-Based Compensation - St_3

Stock-Based Compensation - Stock Option (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended		15 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2024
The Company and Summary of Significant Accounting Policies
Weighted average grant date fair value of options granted		$ 0.01
Granted	0	105,000	0
Unrecognized compensation cost related to employee stock option compensation arrangements	$ 2,000
Expected weighted average period for recognition of unrecognized compensation cost related to employee stock option compensation arrangements	1 year 3 months 18 days
Capitalized stock-based compensation costs	$ 0	$ 0
Recognized stock-based compensation tax benefits	$ 0	$ 0

Stock-Based Compensation - Opti

Stock-Based Compensation - Option, Summary of Assumptions (Details)	12 Months Ended
	Dec. 31, 2022
Fair value of the employee stock options estimated on the grant dates using a Black-Scholes option-pricing model with weighted average assumptions
Estimated term (in years)	5 years 9 months 18 days
Risk-free interest rate	1.85%
Expected volatility	65%
Expected dividend yield	0%

Stock-Based Compensation - Re_2

Stock-Based Compensation - Restricted Stock Units, activity (Details) - RSUs	12 Months Ended
	Dec. 31, 2023 $ / shares shares
The Company and Summary of Significant Accounting Policies
Vesting period	4 years
Number of Shares
Granted | shares	2,099,970
Nonvested, outstanding at the end | shares	2,099,970
Weighted Average Grant Date Fair Value
Granted (in dollars per share) | $ / shares	$ 1.15
Nonvested, outstanding at the end (in dollars per share) | $ / shares	$ 1.15

Stock-Based Compensation - Re_3

Stock-Based Compensation - Restricted Stock Units (Details) - RSUs - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
The Company and Summary of Significant Accounting Policies
Unrecognized compensation cost related to RSUs	$ 2,100,000	$ 1,990,000
Expected weighted average period for recognition of unrecognized compensation cost related to RSUs	3 years 8 months 12 days	3 years 11 months 12 days

Income Taxes - Domestic and for

Income Taxes - Domestic and foreign components of income (loss) before provision for income taxes (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Income Taxes
Domestic			$ (19,910)	$ (30,559)
Foreign			(2,018)	4,268
Income (loss) before provision for income taxes	$ 816	$ (1,343)	$ (21,928)	$ (26,291)

Income Taxes - Provision for in

Income Taxes - Provision for income taxes (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Current
Federal			$ 215,000	$ 128,000
State			1,000	1,000
Foreign			325,000	(8,000)
Total current			541,000	121,000
Deferred
Total provision for income taxes	$ 59,000	$ 50,000	$ 541,000	$ 121,000

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of federal statutory income tax to provision for income taxes (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Income Taxes
Expected benefit at statutory federal rate			$ (4,941,000)	$ (6,717,000)
State tax - net of federal benefit			72,000	100,000
Research and development credits				(564,000)
Foreign income/losses taxed at different rates			14,000	15,000
Unrecognized tax benefits			276,000	126,000
Stock-based compensation			8,000	3,000
Interest expense			333,000	233,000
Remeasurements of net defined benefit liabilities			5,000
Exchange rate difference			287,000	551,000
Change in tax rate			(242,000)	(92,000)
True-up deferred taxes			1,382,000	3,254,000
True-up payable			75,000
Accumulated deficit			67,000	10,000
Change in valuation allowance			3,182,000	3,246,000
Other			23,000	(44,000)
Total provision for income taxes	$ 59,000	$ 50,000	$ 541,000	$ 121,000

Income Taxes - Significant comp

Income Taxes - Significant components of deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets
Net operating loss carryforwards	$ 79,078	$ 78,583
Capitalized costs	5,409	3,095
Accruals and reserves	4,610	4,830
Inventory reserves	267	402
Stock compensation	382	368
Loss on unrealized currency translation	166	160
Research and development credits	2,490	2,490
Financial guarantee liabilities	5,410	5,320
Lease liability	197	4
Provision for credit losses	368	119
Gross deferred tax assets	98,377	95,371
Valuation allowance	(97,628)	(94,446)
Net deferred tax assets	749	925
Deferred tax liabilities
Revaluation of convertible promissory notes	(448)	(742)
Contract assets	(3)	(8)
ROU assets	(298)	(175)
Gross deferred tax liabilities	(749)	(925)
Increase in valuation allowance	$ 3,200	$ 3,200

Income Taxes - Operating loss a

Income Taxes - Operating loss and credit carryforwards (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Operating loss and credit carryforwards
Net operating loss carryforwards	$ 123
Percentage of limitation of taxable income of operating loss carryforwards	80%
Federal
Operating loss and credit carryforwards
Net operating loss carryforwards	$ 334
Research credit carryforwards	2.4
State
Operating loss and credit carryforwards
Net operating loss carryforwards	49
Research credit carryforwards	2.3
Foreign
Operating loss and credit carryforwards
Net operating loss carryforwards	$ 27

Income Taxes - Reconciliation_3

Income Taxes - Reconciliation of the unrecognized tax benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2024
Income Taxes
Beginning gross UTBs	$ 3,203,000	$ 3,106,000
Additions for tax positions taken in a prior year		(35,000)
Additions for tax provision taken in the current year	319,000	1,093,000
Adjustments for tax positions for changes in currency translation	95,000	(223,000)
Reductions for tax positions taken in the prior year	1,051,000	(270,000)
Reductions for tax positions taken in the prior year due to statutes lapsing	(1,585,000)	(468,000)
Ending gross UTBs	3,083,000	3,203,000
UTBs offset by deferred tax assets and/or valuation allowance	(1,419,000)	(1,714,000)
Net UTBs	1,664,000	1,489,000
Amount of unrecognized tax benefits that, if recognized, would affect effective tax rate	1,700,000		$ 1,700,000
Accrued interest and penalties	$ 522,000	$ 449,000

Employee Benefit Plans - 401(k)

Employee Benefit Plans - 401(k) defined contribution plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Employee Benefit Plans
Employer contributions under this plan	$ 64,000	$ 71,000

Employee Benefit Plans - Net _2

Employee Benefit Plans - Net liability for severance payments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Employee Benefit Plans
Liability for severance payments	$ 7,764	$ 7,997	$ 7,248
Deposit	(276)	(308)	(343)
Net liability for severance payments	$ 7,488	$ 7,689	$ 6,905

Related Party Transactions (D_2

Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Related Party Transactions
Other	$ 107		$ 72	$ 104
Interest expense	2,082	$ 935	6,246	3,364
Related party | Anapass
Related Party Transactions
Borrowings	9,653		10,082	10,257
Other	106		212	11
Interest expense	100	100	548	389
Related party | Kyeongho Lee
Related Party Transactions
Borrowings	824		1,474	1,690
Other	87		182	150
Interest expense	$ 22,000	$ 26,000	$ 110	$ 140

Segments and Geographical Inf_3

Segments and Geographical Information (Details) - segment	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Segments and Information
Number of operating segment	1	1

Segments and Geographical Inf_4

Segments and Geographical Information - Long-lived assets by geographic region (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segments and Geographical Information
Total long-lived assets	$ 1,987	$ 2,293	$ 1,921
United States
Segments and Geographical Information
Total long-lived assets	817	930	1,295
South Korea
Segments and Geographical Information
Total long-lived assets	$ 1,170	$ 1,363	$ 626

Subsequent Events (Details)_2

Subsequent Events (Details) - USD ($)		1 Months Ended			12 Months Ended
	Mar. 26, 2024	Mar. 31, 2024	Feb. 29, 2024	Jan. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Mar. 15, 2024
Subsequent Events
Convertible notes					$ 34,033,000	$ 31,166,000
Conversion price					$ 3.50
Number of shares issued on conversion of debt						10,026,354
PIPE financing
Subsequent Events
Shares issued number	4,530,000
Korean won borrowing maturity January 26, 2024
Subsequent Events
Maturity term extension					5 months
Subsequent Event [Member] | i Best Investment Co., Ltd.
Subsequent Events
Maturity term extension		3 months		2 months
Principal amount				$ 776,000
Repayment of loan		$ 2,327,000
Subsequent Event [Member] | GCT R&D
Subsequent Events
Repayment of short term loan		613,000	$ 613,000	613,000
Accrued interest	$ 13,370,000
Number of shares issued on conversion of debt	2,004,535
Subsequent Event [Member] | GCT R&D | PIPE financing
Subsequent Events
Shares issued values	$ 30,200,000
Shares issued number	4,529,967
Subsequent Event [Member] | Equity line of credit (ELOC) facility
Subsequent Events
Maximum aggregate amount of stock issuance							$ 50,000,000
Subsequent Event [Member] | Loans from NJ Holdings | GCT R&D
Subsequent Events
Principal amount				$ 237,000
Debt maturity term				7 days
Interest rate (as a percent)				0%
Repayment of short term loan		237,000	237,000
Subsequent Event [Member] | Convertible promissory notes mature in February and March 2027
Subsequent Events
Convertible notes		$ 11,300,000	$ 11,300,000
Conversion price		$ 6.67	$ 6.67
Subsequent Event [Member] | Convertible promissory note maturing in February 2026
Subsequent Events
Convertible notes			$ 5,000,000
Conversion price			$ 10
Convertible promissory note, conversion to common stock period			6 months
Subsequent Event [Member] | Convertible promissory notes
Subsequent Events
Accrued interest	$ 32,087,000
Number of shares issued on conversion of debt	4,258,223

CONSOLIDATED BALANCE SHEETS_2

CONSOLIDATED BALANCE SHEETS - USD ($)		Dec. 31, 2023		Dec. 31, 2022
Current Assets:
Cash		$ 258,000		$ 1,398,000
Prepaid expenses and other current assets		2,906,000		2,673,000
Total current assets		13,009,000		12,890,000
Total assets		16,428,000		16,476,000
Current Liabilities:
Due to related party		72,000		104,000
Total current liabilities		114,801,000		81,906,000
Promissory note - related party		108,000		76,000
Total liabilities		131,865,000		111,405,000
Commitments and contingencies (Note 5)
Stockholders' deficit:
Preferred stock, $0.0001 par value; 1,000,000 shares authorized; none issued and outstanding
Common stock, par value $0.001 per share, 200,000,000 shares authorized; 129,395,774 and 127,760,265 shares issued and outstanding as of December 31, 2023 and 2022, respectively		3,000	[1]	128,000
Additional paid-in capital		435,626,000		433,990,000
Accumulated deficit		(549,654,000)		(527,185,000)
Total stockholders' deficit	[1]	(115,437,000)		(94,929,000)
Total liabilities and stockholders' deficit		16,428,000		16,476,000
CONCORD ACQUISITION CORP III
Current Assets:
Cash		16,371		521,149
Expense reimbursement receivable from GCT		296,441		0
Prepaid expenses and other current assets		6,418		331,453
Total current assets		319,230		852,602
Marketable securities and cash held in trust account		42,406,594		356,190,233
Total assets		42,725,824		357,042,835
Current Liabilities:
Due to related party		$ 100,920		$ 10,024
Other Liability, Current, Related Party, Type [Extensible Enumeration]		Related Party		Related Party
Accrued income taxes				$ 485,207
Accrued legal expense		$ 1,243,000		2,000
Accrued capital markets advisory expense		2,500,000
Other accounts payable and accrued expenses		275,271		77,569
Excise tax payable		3,184,272
Total current liabilities		7,303,463		574,800
Warrant liability, at fair value		2,383,000		$ 1,812,200
Promissory note - related party		$ 35,000
Other Liability, Noncurrent, Related Party, Type [Extensible Enumeration]		Related Party		Related Party
Sponsor loans, at fair value				$ 1,000,000
Deferred underwriters' commission		$ 5,083,575		12,075,000
Total liabilities		14,805,038		15,462,000
Commitments and contingencies (Note 5)
Common stock subject to possible redemption, 3,941,361 and 34,500,000 shares at redemption value of $10.76 and $10.31 at December 31, 2023 and 2022, respectively		42,411,740		355,643,935
Stockholders' deficit:
Preferred stock, $0.0001 par value; 1,000,000 shares authorized; none issued and outstanding
Accumulated deficit		(14,491,817)		(14,063,963)
Total stockholders' deficit		(14,490,954)		(14,063,100)
Total liabilities and stockholders' deficit		42,725,824		357,042,835
CONCORD ACQUISITION CORP III | Class A common stock
Stockholders' deficit:
Common stock, par value $0.001 per share, 200,000,000 shares authorized; 129,395,774 and 127,760,265 shares issued and outstanding as of December 31, 2023 and 2022, respectively		863		0
CONCORD ACQUISITION CORP III | Class A common stock subject to possible redemption
Current Liabilities:
Common stock subject to possible redemption, 3,941,361 and 34,500,000 shares at redemption value of $10.76 and $10.31 at December 31, 2023 and 2022, respectively		$ 42,411,740		355,643,935
CONCORD ACQUISITION CORP III | Class B common stock
Stockholders' deficit:
Common stock, par value $0.001 per share, 200,000,000 shares authorized; 129,395,774 and 127,760,265 shares issued and outstanding as of December 31, 2023 and 2022, respectively				$ 863
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

CONSOLIDATED BALANCE SHEETS (_2

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares authorized	82,352,000
Preferred stock, shares issued	0
Preferred stock, shares outstanding	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	24,166,000	127,760,265
Common stock, shares outstanding	24,166,000	24,166,000
CONCORD ACQUISITION CORP III
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
CONCORD ACQUISITION CORP III | Class A common stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
CONCORD ACQUISITION CORP III | Class A common stock subject to possible redemption
Common stock subject to possible redemption shares outstanding	3,941,361	34,500,000
Common stock subject to possible redemption price per share	$ 10.76	$ 10.31
CONCORD ACQUISITION CORP III | Class A common stock not subject to possible redemption
Common stock, shares issued	8,624,999	0
Common stock, shares outstanding	8,624,999	0
CONCORD ACQUISITION CORP III | Class B common stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares issued	1	8,625,000
Common stock, shares outstanding	1	8,625,000

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income (loss) from operations	$ (14,558,000)	$ (22,753,000)
Other income (loss):
Income (loss) before provision for income taxes	(21,928,000)	(26,291,000)
Provision for income taxes	(541,000)	(121,000)
Net income (loss)	$ (22,469,000)	$ (26,412,000)
Weighted average number of common shares used in computing net loss per common share - basic	128,459,102	92,958,570
Weighted average number of common shares used in computing net loss per common share - diluted	128,459,102	92,958,570
Net loss per common share - basic	$ (0.17)	$ (0.31)
Net loss per common share - diluted	$ (0.17)	$ (0.31)
CONCORD ACQUISITION CORP III
Operating costs, net	$ 4,867,708	$ 1,172,506
Income (loss) from operations	(4,867,708)	(1,172,506)
Other income (loss):
Income from operating bank account	3,335
Income from cash and investments held in trust account	6,795,482	5,091,197
Recovery of offering costs attributable to warrant liability	372,678
Change in fair value of warrant liability and sponsor loans	(2,913,800)	21,332,800
Total other income, net	4,257,695	26,423,997
Income (loss) before provision for income taxes	(610,013)	25,251,491
Provision for income taxes	(1,385,741)	(995,207)
Net income (loss)	$ (1,995,754)	$ 24,256,284
CONCORD ACQUISITION CORP III | Class A common stock subject to possible redemption
Other income (loss):
Weighted average number of common shares used in computing net loss per common share - basic	14,374,778	34,500,000
Weighted average number of common shares used in computing net loss per common share - diluted	14,374,778	34,500,000
Net loss per common share - basic	$ (0.09)	$ 0.56
Net loss per common share - diluted	$ (0.09)	$ 0.56
CONCORD ACQUISITION CORP III | Class A and B common stock
Other income (loss):
Weighted average number of common shares used in computing net loss per common share - basic	8,625,000	8,625,000
Weighted average number of common shares used in computing net loss per common share - diluted	8,625,000	8,625,000
Net loss per common share - basic	$ (0.09)	$ 0.56
Net loss per common share - diluted	$ (0.09)	$ 0.56

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' DEFICIT - USD ($)	CONCORD ACQUISITION CORP III Class A common stock Common Stock	CONCORD ACQUISITION CORP III Class B common stock Common Stock	CONCORD ACQUISITION CORP III Additional Paid-in Capital	CONCORD ACQUISITION CORP III Accumulated Deficit	CONCORD ACQUISITION CORP III	Common Stock		Additional Paid-in Capital		Accumulated Deficit		Total
Balance as at beginning at Dec. 31, 2021		$ 863		$ (34,576,312)	$ (34,575,449)	$ 13,000		$ 13,682,000		$ (498,536,000)		$ (488,286,000)
Balance at the beginning (in shares) at Dec. 31, 2021		8,625,000			34,500,000
CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' DEFICIT
Excise tax payable attributable to redemption of common stock					$ 0
Increase in redemption value of shares subject to possible redemption				(3,743,935)	(3,743,935)					(2,237,000)		(2,237,000)
Net income (loss)				24,256,284	24,256,284					(26,412,000)		(26,412,000)
Balance as at end at Dec. 31, 2022		$ 863		(14,063,963)	$ (14,063,100)	2,000	[1]	434,116,000	[1]	(527,185,000)	[1]	(94,929,000)	[1]
Balance at the end (in shares) at Dec. 31, 2022		8,625,000			34,500,000
CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' DEFICIT
Net income (loss)										(1,393,000)		(1,393,000)
Balance as at end at Mar. 31, 2023						2,000		434,119,000		(528,578,000)		(95,645,000)
Balance as at beginning at Dec. 31, 2022		$ 863		(14,063,963)	$ (14,063,100)	2,000	[1]	434,116,000	[1]	(527,185,000)	[1]	(94,929,000)	[1]
Balance at the beginning (in shares) at Dec. 31, 2022		8,625,000			34,500,000
CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' DEFICIT
Contribution - non-redemption agreements			$ 6,981,310		$ 6,981,310
Fair value of shareholder non-redemption agreements			$ (6,981,310)		(6,981,310)
Excise tax payable attributable to redemption of common stock				(3,184,272)	(3,184,272)
Conversion of Class B common stock to Class A common stock	$ 863	$ (863)
Conversion of Class B common stock to Class A common stock (in shares)	8,624,999	(8,624,999)
Partial waiver of deferred underwriters' commission				6,618,747	6,618,747
Extinguishment of debt				3,343,000	3,343,000
Increase in redemption value of shares subject to possible redemption				(5,209,575)	(5,209,575)							0
Net income (loss)				(1,995,754)	(1,995,754)					(22,469,000)		(22,469,000)
Balance as at end at Dec. 31, 2023	$ 863			$ (14,491,817)	$ (14,490,954)	3,000	[1]	435,752,000	[1]	(549,654,000)	[1]	(115,437,000)	[1]
Balance at the end (in shares) at Dec. 31, 2023	8,624,999	1			3,941,361
CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' DEFICIT
Net income (loss)										757,000		757,000
Balance as at end at Mar. 31, 2024						$ 5,000		$ 487,006,000		$ (548,897,000)		$ (62,360,000)
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ 757,000	$ (1,393,000)	$ (22,469,000)	$ (26,412,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Income from cash and investments held in trust account			(8,000)	(4,000)
Change in fair value of warrants subject to forfeiture	4,626,000
Changes in operating assets and liabilities:
Income taxes payable	(83,000)		255,000	57,000
Net cash used in operating activities	(14,413,000)	(1,480,000)	(8,827,000)	(18,087,000)
Cash flows from investing activities:
Net cash used in investing activities		(118,000)	(331,000)	(903,000)
Cash flows from financing activities:
Net cash provided by financing activities	30,274,000	552,000	8,149,000	19,273,000
Net increase (decrease) in cash and cash equivalents	15,864,000	(1,098,000)	(1,140,000)	147,000
Cash and cash equivalents at beginning of year	258,000	1,398,000	1,398,000	1,251,000
Cash and cash equivalents cash at end of year	16,122,000	300,000	258,000	1,398,000
CONCORD ACQUISITION CORP III
Cash flows from operating activities:
Net loss			(1,995,754)	24,256,284
Adjustments to reconcile net loss to net cash used in operating activities:
Income from cash and investments held in trust account			(6,795,482)	(5,091,197)
Change in fair value of warrants subject to forfeiture			2,913,800	(21,332,800)
Recovery of offering costs attributable to warrant liability			(372,678)
Changes in operating assets and liabilities:
Expense reimbursement receivable from GCT			(296,441)
Prepaid expenses			330,288	389,014
Due to related party			90,896	7,297
Income taxes payable			(490,460)	485,207
Accrued legal expense			1,241,000	(3,000)
Accrued capital markets advisory expense			2,500,000
Other accounts payable and accrued expenses			197,702	(226,869)
Net cash used in operating activities			(2,677,129)	(1,516,064)
Cash flows from investing activities:
Cash withdrawn from trust account to pay taxes			2,137,351	822,658
Cash withdrawn from trust account in connection with redemptions			318,441,770
Net cash used in investing activities			320,579,121	822,658
Cash flows from financing activities:
Proceeds from issuance of promissory note to related party			35,000
Redemption of common stock			(318,441,770)
Net cash provided by financing activities			(318,406,770)
Net increase (decrease) in cash and cash equivalents			(504,778)	(693,406)
Cash and cash equivalents at beginning of year	$ 16,371	$ 521,149	521,149	1,214,555
Cash and cash equivalents cash at end of year			16,371	521,149
Non-cash financing transactions:
Increase in redemption value of shares subject to possible redemption			5,209,575	3,743,935
Non-cash contribution - non-redemption agreements			6,981,310
Partial waiver of deferred underwriter commission			6,618,747
Excise tax payable attributable to redemption of common stock			$ 3,184,272
Conversion of Class B common stock to Class A common stock			863
Extinguishment of debt			$ 3,343,000
Other supplemental cash flow information:
Federal income tax paid			$ 1,876,201	$ 510,000

ORGANIZATION, BUSINESS OPERATIO

ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY	12 Months Ended
	Dec. 31, 2023
CONCORD ACQUISITION CORP III
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY	NOTE 1. ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY Organization and General Concord Acquisition Corp III (the “Company”) is a blank check company incorporated on February 18, 2021, as a Delaware corporation formed for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses (the “Business Combination”). As of December 31, 2023, the Company had not commenced any operations. All activity for the period from February 18, 2021 (inception) through December 31, 2023, relates to the Company’s formation, the Initial Public Offering (as defined below) and, subsequent to the Initial Public Offering, identifying a target company for a Business Combination and completion of the proposed Business Combination (described below). The Company will not generate any operating revenues until after the completion of its initial Business Combination, at the earliest. The Company will generate non-operating income in the form of investment income on cash and cash equivalents from the proceeds derived from the Initial Public Offering, and non-operating income or expense from the changes in the fair value of warrant liability and Sponsor Loans. The Company’s sponsors are Concord Sponsor Group III LLC (the “Sponsor”) (an affiliate of Atlas Merchant Capital LLC), and CA2 Co-Investment LLC (an affiliate of one of the underwriters of the Initial Public Offering) (“CA2 Co-Investment” and, together with the Sponsor, the “Sponsors”). The registration statements for the Initial Public Offering were declared effective by the U.S. Securities and Exchange Commission (the “SEC”) on November 3, 2021 (the “Effective Date”). On November 8, 2021, the Company completed its initial public offering (the “Initial Public Offering” or “IPO”) of 34,500,000 units (“Units”), including the issuance of 4,500,000 Units as a result of the underwriters’ exercise in full of their over-allotment option at an offering price of $10.00 per Unit, generating gross proceeds of $345,000,000. Simultaneously with the closing of the IPO, the Company consummated the private placement of 8,260,606 warrants to the Sponsor and 1,139,394 warrants to CA2 Co-Investment (together, the “Private Placement Warrants”), each at a price of $1.00 per Private Placement Warrants, generating gross proceeds of $9,400,000. The Company also executed promissory notes with the Sponsors, evidencing loans to the Company in the aggregate amount of $6,900,000 (the “Sponsors Loans”). The Sponsor Loans may, by their terms, be repaid or converted into warrants (the “Sponsor Loan Warrants”) at a conversion price of $1.00 per warrant, at the Sponsors’ discretion. The Sponsor Loan Warrants will be identical to the Private Placement Warrants, which are described in Note 5. The Company’s Business Combination must be with one or more target businesses that together have a fair market value equal to at least 80% of the net balance in the Trust Account (as defined below) (excluding the amount of deferred underwriting discounts held and taxes payable on the income earned on the Trust Account) at the time of the signing an agreement to enter into a Business Combination. However, the Company will only complete a Business Combination if the post-Business Combination company owns or acquires 50% or more of the outstanding voting securities of the target or otherwise acquires a controlling interest in the target sufficient for it not to be required to register as an investment company under the Investment Company Act of 1940, as amended (the “Investment Company Act”). There is no assurance that the Company will be able to successfully effect a Business Combination. Upon the closing of the Initial Public Offering, a total of $351,900,000 ($10.20 per Unit) of the net proceeds from the IPO, the Private Placement and the Sponsor Loans was deposited in a trust account (“Trust Account”) and was invested only in U.S. government treasury bills with a maturity of 185 days or less or in money market funds investing solely in U.S. Treasuries and meeting certain conditions under Rule 2a-7 under the Investment Company Act. Except with respect to interest earned on the funds held in the Trust Account that may be released to the Company as described below, the funds held in the Trust Account will not be released from the Trust Account until the earliest of: (1) the completion of the initial Business Combination; (2) the redemption of any public shares properly submitted in connection with a stockholder vote to amend the Company’s amended and restated certificate of incorporation (i) to modify the substance or timing of the Company’s obligation to provide for the redemption of the public shares in connection with the initial Business Combination or to redeem 100% of the public shares if the Company does not complete the initial Business Combination by the Current Extended Date (as defined below) or (ii) with respect to any other provisions relating to stockholders’ rights or pre-initial Business Combination activity; and (3) the redemption of all of the public shares if the Company has not completed the initial Business Combination by the Current Extended Date, subject to applicable law. The proceeds deposited in the Trust Account could become subject to the claims of the Company’s creditors, if any, which could have priority over the claims of the public stockholders. The Company will provide its public stockholders with the opportunity to redeem all or a portion of their public shares upon the completion of the initial Business Combination either: (1) in connection with a stockholder meeting called to approve the Business Combination; or (2) by means of a tender offer. Except as required by applicable law or stock exchange rules, the decision as to whether the Company will seek stockholder approval of a proposed Business Combination or conduct a tender offer will be made by the Company, solely in its discretion. The public stockholders will be entitled to redeem all or a portion of their public shares upon the completion of the initial Business Combination at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, calculated as of two All of the public shares contain a redemption feature which allows for the redemption of such public shares in connection with the Company’s liquidation, if there is a shareholder vote or tender offer in connection with the initial Business Combination and in connection with certain amendments to the Company’s amended and restated certificate of incorporation. The shares of common stock subject to redemption were recorded at redemption value and classified as temporary equity upon the completion of the Initial Public Offering, in accordance with FASB ASC Topic 480, “Distinguishing Liabilities from Equity.” In such case, the Company will proceed with a Business Combination, among other things, if the Company seeks stockholder approval, a majority of the issued and outstanding shares voted are voted in favor of the Business Combination. In April 2023, the Company and the Sponsor entered into Non-Redemption Agreements with a number of the Company’s stockholders in exchange for them agreeing not to redeem shares of the Company’s Class A common stock sold in the IPO (the “Non-Redeemed Shares”) in connection with the special meeting of stockholders called by the Company and held on May 4, 2023 (described below). In exchange for the foregoing commitments not to redeem such shares, the Sponsor has agreed to transfer to such stockholders an aggregate of 999,665 shares of the Company’s Class B common stock (the “Class B shares”), par value $0.0001 per share, held by the Sponsor immediately following consummation of an initial Business Combination. In November 2023, the Sponsor and the holders of the founder shares converted an aggregate of 8,624,999 shares of Class B common stock to shares of Class A common stock. On May 4, 2023, the Company’s stockholders approved at the special meeting of stockholders a proposal to amend the Company’s amended and restated certificate of incorporation (the “charter”) to extend the date by which the Company has to consummate a business combination from May 8, 2023 (the “Termination Date”) to November 8, 2023, or such earlier date as may be determined by the board of directors of the Company (such later date, the “Extended Date”). In connection with the votes to approve the Charter Amendment, the holders of 30,460,066 shares of Class A common stock of the Company properly exercised their right to redeem their shares for cash at a redemption price of approximately $10.42 per share, for an aggregate redemption amount of approximately $317,000,000, leaving approximately $42,000,000 in the Trust Account. In November 2023, the Company and the Sponsor entered into certain Non-Redemption Agreements with a number of the Company’s stockholders in exchange for them agreeing not to redeem shares of the Company’s Class A common stock sold in the IPO in connection with the special meeting of stockholders called by the Company and held on November 7, 2023 (described below). In exchange for the foregoing commitments not to redeem such shares, the Company has agreed to allocate to such investors an aggregate of 781,961 shares of Class A common stock (the “Promote Shares”) and the Sponsor has agreed to surrender and forfeit to the Company for no consideration a number of shares of Class B common stock equal to the number of Promote Shares upon closing of an initial Business Combination. On November 7, 2023, the Company’s stockholders approved at the special meeting of stockholders a proposal to amend the Company’s charter to further extend the date by which the Company has to consummate a Business Combination from the Extended Date to August 8, 2024, or such earlier date as may be determined by the board of directors of the Company (such later date, the “Current Extended Date”). In connection with the votes to approve such a proposal, the holders of an additional 98,573 shares of Class A common stock of the Company properly exercised their right to redeem their shares for cash at a redemption price of approximately $10.70 per share, for an aggregate redemption amount of approximately $1,100,000, leaving approximately $42,200,000 in the Trust Account and 3,941,361 shares of Class A common stock subject to possible redemption outstanding immediately following these redemptions. Deferred Underwriters’ Commission In December 2023, one of the underwriters waived any right to receive the deferred underwriters’ commission of $6,991,425 and will therefore receive no additional underwriting commissions in connection with the closing of a Business Combination. After one of the Company’s underwriters waived their right to the deferred underwriters’ commission, the remaining underwriters are entitled to a deferred underwriters’ commission of $5,083,575 of the gross proceeds of the IPO held in the Trust Account upon the completion of the Company’s initial Business Combination subject to the terms of the underwriting agreement. (see Note 4). Proposed Business Combination On November 2, 2023, the Company entered into a business combination agreement (the “Business Combination Agreement”) with GCT Semiconductor, Inc., a Delaware corporation (“GCT”), and Gibraltar Merger Sub Inc., a Delaware corporation and a direct, wholly-owned subsidiary of the Company (“Merger Sub”). Pursuant to the Business Combination Agreement, the parties will, subject to the satisfaction or waiver of the conditions contained in the Business Combination Agreement, consummate a business combination transaction pursuant to which Merger Sub will merge with and into GCT, with GCT surviving the merger as a wholly-owned subsidiary of the Company (the “Merger” and, together with the other transactions contemplated by the Business Combination Agreement, the “Transactions” and the closing of the Transactions, the “Closing”). The aggregate equity consideration to be paid to GCT’s stockholders and other equity holders in the Transactions will be equal to the quotient of (i) the Company Value (as defined below) divided by (ii) $10.00. Immediately prior to the Closing, all of the outstanding principal and accrued interest under the outstanding promissory notes issued by GCT that can be converted into shares of GCT common stock will be so converted in accordance with their terms. The “Company Value” means an amount equal to $350,000,000, minus the amount of indebtedness of GCT immediately prior to the Closing, plus the amount of GCT’s cash and cash equivalents immediately prior to the Closing (with standard exceptions), plus the aggregate exercise price of all “in-the-money” warrants of GCT outstanding immediately prior to the Closing. Following the Closing, the Company will issue up to an aggregate of 20,000,000 additional shares of its common stock to the stockholders of GCT as of immediately prior to the Closing and certain other persons, including the PIPE Investors (as defined below) (collectively, the “GCT Recipients”), if the volume weighted average price (the “VWAP”) of the shares of the Company’s common stock equals or exceeds certain minimum share prices at any time during the period starting 60 days following the Closing and expiring on the fifth anniversary of the Closing (the “Earnout Period”), as follows: (i) 6,666,667 shares if the VWAP of the shares of the common stock equals or exceeds $12.50 for any 20 trading days within a period of 30 consecutive trading days during the Earnout Period; (ii) 6,666,666 shares if the VWAP of the shares of the common stock equals or exceeds $15.00 for any 20 trading days within a period of 30 consecutive trading days during the Earnout Period; and (iii) 6,666,667 shares if the VWAP of the shares of the common stock equals or exceeds $17.50 for any 20 trading days within a period of 30 consecutive trading days during the Earnout Period. Such shares will also become issuable under certain circumstances if a “change of control” of the Company occurs following the Closing but prior to the applicable earnout expiration date and the price per share in the change of control equals or exceeds the applicable price target. Concurrently with the execution of the Business Combination Agreement, certain investors (the “PIPE Investors”) entered into subscription agreements (the “PIPE Subscription Agreements”) pursuant to which the PIPE Investors have committed to purchase in a private placement an aggregate of 4,484,854 shares of the Company’s Class A common stock (the “PIPE Shares”) at a purchase price of $6.67 per share and an aggregate purchase price of approximately $29,900,000 (the “PIPE Investment”). The purchase of the PIPE Shares is conditioned upon, among other things, the consummation of the Transactions and will be consummated immediately prior to or substantially concurrently with the Closing. The public warrants included as part of Units sold in the IPO (the “Public Warrants”) and Private Placement Warrants include certain down-round provisions under which their exercise price may be adjusted, if (a) the Company issues additional shares of the Company’s Class A common stock or securities convertible into or exercisable or exchangeable for shares of the Company’s Class A common stock for capital raising purposes in connection with the closing of its initial business combination at an issue price or effective issue price of less than $9.20 per share of the Company’s Class A common stock (the “Newly Issued Price”), (b) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for the funding of an initial business combination on the date of the consummation of such initial business combination (net of redemptions), and (c) the volume weighted average trading price of the Company’s Class A common stock during the twenty (20) trading day period starting on the trading day prior to the day on which the Company consummates an initial business combination (such price, the “Market Value”) is below $9.20 per share, the price per share (including in cash or by payment of warrants pursuant to a “cashless exercise,” to the extent permitted) at which shares of the Company’s Class A common stock may be purchased at the time a warrant is exercised will be adjusted (to the nearest cent) to be equal to 115% of the higher of the Market Value and the Newly Issued Price, and the $18.00 per share redemption trigger prices will be adjusted (to the nearest cent) to be equal to 180% of the higher of the Market Value and the Newly Issued Price. Concurrently with the execution of the Business Combination Agreement, the Company entered into a sponsor support agreement (the “Sponsor Support Agreement”) with GCT, the Sponsor and CA2 Co-Investment LLC (“CA2”). Pursuant to the Sponsor Support Agreement, the Sponsor and CA2 have, among other things, agreed to vote all of their shares of the Company’s common stock in favor of the approval of the Transactions, including the Merger, not to redeem any of their shares of the Company’s common stock and to waive their anti-dilution protections with respect to their shares of the Company’s Class B common stock. In addition, the Sponsor and CA2 agreed that a portion of up to an aggregate of 1,920,375 shares of common stock to be issued to them at Closing (collectively, the “Sponsor Earnout Shares”) will be unvested and subject to forfeiture as of the Closing, and will only vest if certain share price trading thresholds are satisfied during a specified period of time following the Closing. The Sponsor and CA2 further agreed that (i) 1,399,107 shares of common stock to be held by them at Closing, (ii) any portion of the Sponsor Earnout Shares not unvested and made subject to forfeiture as of the Closing and (iii) up to an aggregate of 2,820,000 Private Placement Warrants to be held by them at Closing may be allocated by GCT to the GCT Recipients, and transferred to the GCT Recipients at Closing (without any vesting conditions). The Sponsor and CA2 also agreed (i) to forfeit up to an additional 2,820,000 Private Placement Warrants held by them at Closing, to the extent not allocated prior to the Closing to certain third parties, including prospective PIPE Investors and holders of shares of the Company’s Class A common stock who agree not to redeem their shares in connection with any extension of the Company’s deadline to consummate an initial business combination, and (ii) to forgive all amounts outstanding under the Sponsor Loans. Additionally, GCT has agreed to pay (i) all SEC and other regulatory filing fees incurred in connection with the proposed Business Combination, (ii) such expenses incurred in connection with printing, mailing, and soliciting proxies with respect to the Registration Statement and Proxy Statement, (iii) such expenses incurred in connection with any filings with or approvals from the NYSE in connection with the proposed Business Combination, including any expenses and fees incurred by the Company to maintain the minimum NYSE listing requirements, (iv) such expenses relating to the filing fees and notification requirements under the HSR Act, and (v) the SPAC Extension Expenses. As of December 31, 2023 the Company has received $413,529 for the reimbursement of expenses and offset the reported expenses by $709,970 for amounts reimbursed or reimbursable by GCT. As of December 31, 2022, no amounts were received from GCT and no expenses were offset for any expense to be incurred by GCT related to the proposed Business Combination. As of December 31, 2023 and 2022, $296,441 and $0, respectively, is due from GCT and reported on the balance sheet as expense reimbursement receivable from GCT. On February 27, 2024, the Company held a special meeting in lieu of the 2024 annual meeting of stockholders in connection with the proposed Business Combination. At the Special Meeting, the Company’s stockholders approved the Business Combination Proposal, the Charter Amendment Proposal, each of the Governance Proposals (on a non-binding advisory basis), the election of each director nominee pursuant to the Election of Directors Proposal, the Incentive Award Plan Proposal, the Employee Stock Purchase Plan Proposal, and the NYSE Proposal, in each case as defined and described in greater detail in the Final Prospectus. Initial Business Combination The Company has until the Current Extended Date (the “Combination Period”) to complete the initial Business Combination. If the Company is unable to complete the initial Business Combination within the Combination Period or during any Extension Period (as defined below), the Company will: (1) cease all operations except for the purpose of winding up; (2) as promptly as reasonably possible but not more than ten The Sponsors, officers and directors have agreed to waive: (1) their redemption rights with respect to any Founder shares (as described in Note 5) or Converted Shares (as described below) and public shares held by them, as applicable, in connection with the completion of the initial Business Combination; (2) their redemption rights with respect to any Founder shares or Converted Shares and public shares held by them in connection with a stockholder vote to approve an amendment to the Company’s amended and restated certificate of incorporation (A) to modify the substance or timing of the obligation to allow redemptions in connection with the initial Business Combination or to redeem 100% of the public shares if the Company has not consummated the initial Business Combination within the Combination Period or (B) with respect to any other provision relating to stockholders’ rights or pre-initial Business Combination activity; and (3) their rights to liquidating distributions from the Trust Account with respect to any Founder shares or Converted Shares they hold if the Company fails to complete the initial Business Combination within the Combination Period or during any extended time that the Company has to consummate a Business Combination beyond the Combination Period as a result of a stockholder vote to amend the Company’s amended and restated certificate of incorporation (an “Extension Period”) (although they will be entitled to liquidating distributions from the Trust Account with respect to any public shares they hold if the Company fails to complete the initial Business Combination within the Combination Period). The Sponsor has agreed that it will be liable to the Company if and to the extent any claims by a third party for services rendered or products sold to the Company, or a prospective target business with which the Company has discussed entering into a transaction agreement, reduce the amount of funds in the Trust Account to below: (1) $10.20 per public share; or (2) such lesser amount per public share held in the Trust Account as of the date of the liquidation of the Trust Account due to reductions in the value of the trust assets, in each case net of the amount of interest which may be withdrawn to pay taxes, except as to any claims by a third party who executed a waiver of any and all rights to seek access to the Trust Account and except as to any claims under the Company’s indemnity of the underwriters of the Initial Public Offering against certain liabilities, including liabilities under the Securities Act of 1933, as amended (the “Securities Act”). Moreover, in the event that an executed waiver is deemed to be unenforceable against a third party, the Sponsors will not be responsible to the extent of any liability for such third-party claims. The Company has not independently verified whether the Sponsor has sufficient funds to satisfy its indemnity obligations and believe that the Sponsor’s only assets are securities of the Company and, therefore, the Sponsor may not be able to satisfy those obligations. The Company has not asked the Sponsor to reserve for such obligations. Conversion of Class B Shares to Class A Shares On November 16, 2023, the holders of the Company’s Class B common stock, par value $0.0001 per share, converted 8,624,999 shares of the Company’s Class B Liquidity and Going Concern Considerations As of December 31, 2023, the Company had cash on hand of $16,371 held outside of the Trust Account and available for working capital purposes. Investment income on the cash held in the Trust Account may be released to the Company to pay taxes (excluding excise taxes) and up to $100,000 to pay dissolution expenses. During the year ended December 31, 2023, the Company withdrew $2,137,351 from the Trust Account for the payment of taxes. The Sponsor agreed to loan the Company up to $350,000 to be used to pay operating expenses and $35,000 is drawn down on this loan. Additionally, GCT has agreed to reimburse the Company for certain Business Combination related expenses. As of December 31, 2023 $296,441 is due from GCT. If the estimate of the costs of identifying a target business, undertaking in-depth due diligence and negotiating a Business Combination are less than the actual amount necessary to do so, the Company may have insufficient funds available to operate our business prior to a Business Combination. Moreover, the Company may need to obtain additional financing either to complete a Business Combination or because the Company becomes obligated to redeem a significant number of public shares upon consummation of a Business Combination, in which case the Company may issue additional securities or incur debt in connection with such Business Combination. Subject to compliance with applicable securities laws, the Company would only complete such financing simultaneously with the completion of a Business Combination. If the Company is unable to complete a Business Combination because it does not have sufficient funds available, the Company will be forced to cease operations and liquidate the Trust Account. In addition, following a Business Combination, if cash on hand is insufficient, the Company may need to obtain additional financing in order to meet its obligations. The Company has until the Current Extended Date to consummate a Business Combination. If a Business Combination is not consummated by this date and any additional extension(s) are not obtained, there will be a mandatory liquidation and subsequent dissolution of the Company. Although the Company intends to consummate a Business Combination on or before the Current Extended Date, it is uncertain whether the Company will be able to consummate a Business Combination by this time. In connection with the Company’s assessment of going concern considerations in accordance with ASC Subtopic 205-40, “Presentation of Financial Statements – Going Concern”, Management has determined that the mandatory liquidation, should a Business Combination not occur, and an additional extension is not obtained, and potential subsequent dissolution, as well as the potential for the Company to have insufficient funds available to operate its business prior to a Business Combination, raise substantial doubt about the Company’s ability to continue as a going concern. No adjustments have been made to the carrying amounts and classification of assets or liabilities should the Company be required to liquidate after the Current Extended Date. Notification from the New York Stock Exchange On January 19, 2024, the Company received a notification (the “Notice”) from the New York Stock Exchange (the “NYSE”) informing the Company that, because the number of public stockholders is less than 300, the Company is not in compliance with Section 802.01B of the NYSE Listed Company Manual (the “Listing Rule”). The Listing Rule requires the Company to maintain a minimum of 300 public stockholders on a continuous basis. The Notice specifies that the Company has 45 days to submit a business plan that demonstrates how the Company expects to return to compliance with the Listing Rule within 18 months of receipt of the Notice. The business plan will be reviewed by a Committee of the NYSE. The Committee will either accept the plan, at which time the Company will be subject to quarterly monitoring for compliance with this business plan, or the Committee will not accept the business plan and the Company will be subject to suspension and delisting procedures. The Company submitted its Compliance Plan on February 28, 2024. Although the Company submitted a Compliance Plan on February 28, 2024, the Company cannot assure that its securities will continue to be listed on the NYSE in the future or prior to a Business Combination. Risks and Uncertainties The continuing military conflict between the Russian Federation and Ukraine, the military action between Hamas and Israel and the risk of escalations of other military conflicts have created and are expected to create global economic consequences. The specific impact on the Company’s financial condition, results of operations, and cash flows is not determinable as of the date of these consolidated financial statements.

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”)
CONCORD ACQUISITION CORP III
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying consolidated financial statements of the Company are presented in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary. All intercompany transactions have been eliminated. Reclassification Certain prior period amounts have been reclassified to conform to the current period presentation. The reclassification had no impact on operating costs, net, net (loss) income, earnings per share, current or total assets or liabilities, or total equity. Emerging Growth Company The Company is an “emerging growth company,” as defined in Section 2(a) of the Securities Act of 1933, as amended, as modified by the Jumpstart Our Business Startups Act of 2012, (the “JOBS Act”), and it may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies including, but not limited to, not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act, reduced disclosure obligations regarding executive compensation in its periodic reports and proxy statements, and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and stockholder approval of any golden parachute payments not previously approved. Further, Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Exchange Act) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that a company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but any such election to opt out is irrevocable. The Company has elected not to opt out of such extended transition period which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company, as an emerging growth company, can adopt the new or revised standard at the time private companies adopt the new or revised standard. This may make comparison of the Company’s consolidated financial statements with another public company which is neither an emerging growth company nor an emerging growth company which has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates. Cash and Cash Equivalents The Company considers all short-term investments with an original maturity of three months or less when purchased to be cash equivalents. The Company did not have any cash equivalents as of December 31, 2023 and 2022. Expense Reimbursement Receivable from GCT In association with the Company’s proposed Business Combination, GCT has agreed to pay (i) all SEC and other regulatory filing fees incurred in connection with the proposed Business Combination, (ii) such expenses incurred in connection with printing, mailing, and soliciting proxies with respect to the Registration Statement and Proxy Statement, (iii) such expenses incurred in connection with any filings with or approvals from the NYSE in connection with the proposed Business Combination, including any expenses and fees incurred by the Company to maintain the minimum NYSE listing requirements, (iv) such expenses relating to the filing fees and notification requirements under the HSR Act, and (v) the SPAC Extension Expenses. As of December 31, 2023 the Company has received $413,529 for the reimbursement of expenses and offset the reported expenses by $709,970 for amounts reimbursed or reimbursable by GCT. As of December 31, 2022, no amounts were received from GCT and no expenses were offset for any expense to be incurred by GCT related to the proposed Business Combination. As of December 31, 2023 and 2022, $296,441 and $0, respectively, is due from GCT and reported on the balance sheet as expense reimbursement receivable from GCT. Marketable Securities and Cash Held in Trust Account As of December 31, 2023 and 2022, investments held in Trust Account consisted of interest bearing demand deposits and mutual funds that invest primarily in U.S. government securities, respectively, and generally have a readily determinable fair value. Such cash and investments in mutual funds are presented on the consolidated balance sheets at fair value at the end of the reporting period. Interest, dividends, gains and losses resulting from the change in fair value of these securities are included in income from investments held in the Trust Account in the accompanying consolidated statements of operations. The estimated fair values of investments held in the Trust Account are determined using available market information. During the year ended December 31, 2022 the Trust Account held U.S. Treasury securities classified as held-to-maturity in accordance with ASC Topic 320, “Investments — Debt and Equity Securities.” Held-to-maturity securities are those securities which the Company has the ability and intent to hold until maturity. Held-to-maturity treasury securities are recorded at amortized cost on the accompanying balance sheet. A decline in the market value of held-to-maturity securities below cost that is deemed to be other than temporary, results in an impairment that reduces the carrying costs to such securities’ fair value. The impairment is charged to earnings and a new cost basis for the security is established. To determine whether an impairment is other than temporary, the Company considers whether it has the ability and intent to hold the investment until a market price recovery and considers whether evidence indicating the cost of the investment is recoverable outweighs evidence to the contrary. Evidence considered in this assessment includes the reasons for the impairment, the severity and the duration of the impairment, changes in value subsequent to year-end, forecasted performance of the investee, and the general market condition in the geographic area or industry the investee operates in. During the year ended December 31, 2022, premiums and discounts were amortized or accreted over the life of the related held-to-maturity security as an adjustment to yield using the effective-interest method. Such amortization and accretion is included in the “income from cash and investments held in Trust Account” line item in the consolidated statement of operations. Accretion of the discounts amounted to $320,030 for the year ended December 31, 2022. There were no such securities held with discounts or premiums during the year ended December 31, 2023, and as a result there was no accretion during such period. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist of a cash account in a financial institution, which, at times, may exceed the Federal Depository Insurance Coverage of $250,000. At December 31, 2023 and 2022, the Company has not experienced losses on this account. Offering Costs The Company complies with the requirements of ASC 340-10-S99-1 and SAB Topic 5A-“Expenses of Offering”. Offering costs consist of legal, accounting, underwriting discount and other costs that are directly related to the IPO. Accordingly, offering costs were initially charged to stockholders’ equity (consisting of underwriting discount, deferred underwriters’ commission, and other offering costs offset by offering costs attributable to the warrant liability and recorded in the statement of operations). The Company adopted the residual method to allocate the gross proceeds between Class A common stock and warrants based on their relative fair values. Deferred Underwriters’ Commission The Company complies with ASC Topic 405 “Liabilities” and derecognized the deferred underwriting commission liability upon being released of the obligation by the underwriters. Upon the IPO, the Company treated the deferred underwriter’s commission as an offering cost (as discussed above). To account for the waiver of the deferred underwriting commission, the Company reduced the deferred underwriter commission liability and reversed the previously recorded cost of issuing the instruments in the IPO, which included recognizing a contra-expense in the amount previously allocated to liability classified warrants and expensed upon the IPO, and reduced the accumulated deficit and increased income available to Class B common stock, which was previously allocated to the Class A common stock subject to redemption and accretion recognized at the IPO date. Common Stock Subject to Possible Redemption The Company accounts for its shares of Class A common stock subject to possible redemption in accordance with the guidance in ASC Topic 480. Shares of Class A common stock subject to mandatory redemption (if any) are classified as a liability instrument and is measured at fair value. Conditionally redeemable shares of Class A common stock (including shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, shares of Class A common stock are classified as stockholders’ equity. The Company’s shares of Class A common stock feature certain redemption rights that are considered to be outside of the Company’s control and subject to the occurrence of uncertain future events. Accordingly, all shares of Class A common stock subject to possible redemption are presented at redemption value as temporary equity, outside of the stockholders’ deficit section of the Company’s balance sheet. The shares of Class A common stock sold as part of the Units in the IPO contain a redemption feature which allows for the redemption of such public shares in connection with the Company’s liquidation, if there is a shareholder vote or tender offer in connection with a Business Combination and in connection with certain amendments to the Company’s amended and restated certificate of incorporation. In accordance with the accounting treatment for redeemable equity instruments, which has been codified in ASC 480-10-S99, redemption provisions not solely within the control of the Company require Class A common stock subject to redemption to be classified outside of permanent equity. Therefore, all shares of Class A common stock have been classified outside of permanent equity. In connection with the votes to approve the Charter Amendment at the special meeting of stockholders on May 4, 2023, the holders of 30,460,066 shares of Class A common stock of the Company properly exercised their right to redeem their shares for cash at a redemption price of approximately $10.42 per share, for an aggregate redemption amount of approximately $317,000,000. In connection with the votes to approve the Second Charter Amendment at the special meeting of stockholders on November 7, 2023, the holders of an additional 98,573 shares of Class A common stock of the Company properly exercised their right to redeem their shares for cash at a redemption price of approximately $10.70 per share, for an aggregate redemption amount of approximately $1,100,000. The Company recognizes changes in redemption value immediately as they occur and adjusts the carrying value of redeemable common stock to equal the redemption value at the end of each reporting period. Increases or decreases in the carrying amount of redeemable common stock are affected by charges against additional paid-in capital (to the extent available) and accumulated deficit. For the year ended December 31, 2023 and 2022, the changes in Class A common stock subject to possible redemption are as follows: ​ ​ ​ ​ ​ ​ ​ Class A common stock subject to possible redemption ​ ​ ​ Shares ​ Amount January 1, 2022 34,500,000 ​ $ 351,900,000 Plus: ​ Increase in redemption value of shares subject to possible redemption — ​ 3,743,935 December 31, 2022 34,500,000 ​ $ 355,643,935 ​ ​ ​ ​ ​ ​ January 1, 2023 34,500,000 ​ $ 355,643,935 Plus: ​ Increase in redemption value of shares subject to possible redemption — ​ 5,209,575 Less: ​ Redemption (30,558,639) ​ (318,441,770) December 31, 2023 3,941,361 ​ $ 42,411,740 ​ Fair Value of Financial Instruments The fair value of the Company’s assets and liabilities, which qualify as financial instruments under the FASB ASC 820, “Fair Value Measurement” approximates the carrying amounts represented in the balance sheets, primarily due to their short-term nature. Fair Value Measurements Fair value is defined as the price that would be received for sale of an asset or paid for transfer of a liability, in an orderly transaction between market participants at the measurement date. GAAP establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). These tiers include: ● Level 1, defined as observable inputs such as quoted prices (unadjusted) for identical instruments in active markets; ● Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable such as quoted prices for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active; and ● Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions, such as valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. In some circumstances, the inputs used to measure fair value might be categorized within different levels of the fair value hierarchy. In those instances, the fair value measurement is categorized in its entirety in the fair value hierarchy based on the lowest level input that is significant to the fair value measurement. Derivative Financial Instruments The Company evaluates its financial instruments to determine if such instruments are derivatives or contain features that qualify as embedded derivatives in accordance with ASC Topic 815, “Derivatives and Hedging”. Derivative instruments are initially recorded at fair value on the grant date and re-valued at each reporting date, with changes in the fair value reported in the statement of operations. Derivative assets and liabilities are classified in the balance sheet as current or non-current based on whether or not net-cash settlement or conversion of the instrument could be required within 12 months of the balance sheet date. Warrant Liability The Company accounts for the 26,650,000 warrants issued in connection with the Initial Public Offering (the 17,250,000 Public Warrants and the 9,400,000 Private Placement Warrants) in accordance with the guidance contained in ASC Topic 815-40 “Contracts in Entity’s Own Equity”. Such guidance provides that because the warrants do not meet the criteria for equity classification thereunder, each warrant must be classified as a liability. Accordingly, the Company classifies each warrant as a liability at its fair value. This liability is subject to re-measurement at each balance sheet date. With each such re-measurement, the warrant liability will be adjusted to fair value, with the change in fair value recognized in the Company’s consolidated statement of operations. Sponsor Loans The Company has elected to account for the $6,900,000 (original principal amount) in Sponsor Loans using the fair value option in accordance with the guidance contained in ASC 825-10-25. The fair value option provides an option to elect fair value as an alternative measurement for selected financial assets, financial liabilities, unrecognized firm commitments, and written loan commitments. The Company has elected to apply the fair value option to the Sponsor Loans to simplify the accounting model applied to that class of financial instruments. See Notes 3 and 6 for additional information. Stock-Based Compensation The sale or transfers of the Founder Shares to members of the Company’s board of directors, as described in Note 5, is within the scope of FASB ASC Topic 718, “Compensation-Stock Compensation” (“ASC 718”). Under ASC 718, stock-based compensation associated with equity classified awards is measured at fair value upon the grant date. The Founder Shares were effectively sold or transferred subject to a performance condition (i.e., the occurrence of a Business Combination). Compensation expense related to the Founder Shares is recognized only when the performance condition is probable of occurrence under the applicable accounting literature in this circumstance. A business combination is not probable until it is completed. Stock-based compensation would be recognized at the date a Business Combination is considered probable in an amount equal to the number of Founder Shares times the grant date fair value per share (unless subsequently modified) less the amount initially received for the purchase of the Founder Shares. As of December 31, 2023 and for all prior periods, the Company determined that a Business Combination is not considered probable until a business combination is completed, and therefore, no stock-based compensation expense has been recognized. Income Taxes The Company accounts for income taxes under ASC 740 Income Taxes (“ASC 740”). ASC 740 requires the recognition of deferred tax assets and liabilities for both the expected impact of differences between the financial statement and tax basis of assets and liabilities and for the expected future tax benefit to be derived from tax loss and tax credit carry forwards. ASC 740 additionally requires a valuation allowance to be established when it is more likely than not that all or a portion of deferred tax assets will not be realized. The effective tax rate differs from the statutory tax rate of 21% for the year ended December 31, 2023 and 2022, primarily due to changes in fair value of the warrant liability and Sponsor Loans, which are not currently recognized in taxable income, non-deductible start-up costs, offering costs attributable to the warrants, and the valuation allowance on the deferred tax assets. ASC 740 also clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements and prescribes a recognition threshold and measurement process for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more-likely-than-not to be sustained upon examination by taxing authorities. ASC 740 also provides guidance on derecognition, classification, interest and penalties, accounting in interim period, disclosure and transition. The Company recognizes accrued interest and penalties related to unrecognized tax benefits. There were no unrecognized tax benefits and no amounts accrued for interest and penalties as of December 31, 2023 and 2022. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. The Company has identified the United States as its only “major” tax jurisdiction. The Company is subject to income tax examinations by major taxing authorities since inception. These examinations may include questioning the timing and amount of deductions, the nexus of income among various tax jurisdictions and compliance with federal and state tax laws. The Company’s management does not expect that the total amount of unrecognized tax benefits will materially change over the next twelve months. On August 16, 2022, the Inflation Reduction Act of 2022 (the “IRA”) was signed into federal law. The IRA provides for, among other things, a new U.S. federal 1% excise tax on certain repurchases (including redemptions) of stock by publicly traded U.S. corporations and certain U.S. subsidiaries of publicly traded non-U.S. corporations (each, a “covered corporation”). Because the Company is a Delaware corporation and its securities are trading on the NYSE, the Company is a “covered corporation” for this purpose. The excise tax is imposed on the repurchasing corporation itself, not its stockholders from which shares are repurchased. The amount of the excise tax is generally 1% of the fair market value of the shares repurchased at the time of the repurchase. However, for purposes of calculating the excise tax, repurchasing corporations are permitted to net the fair market value of certain new stock issuances against the fair market value of stock repurchases during the same taxable year. In addition, certain exceptions apply to the excise tax. The U.S. Department of Treasury has been given authority to provide regulations and other guidance to carry out, and prevent the abuse or avoidance of the excise tax. The IRA applies only to repurchases that occur after December 31, 2022. Any redemption or other repurchase that occurs in connection with a Business Combination may be subject to the excise tax. Whether and to what extent we would be subject to the excise tax would depend on a number of factors, including (i) the fair market value of the redemptions and repurchases in connection with a Business Combination, (ii) the timing, nature and amount of the equity issued in connection with a Business Combination (or otherwise issued not in connection with a Business Combination but issued within the same taxable year of a Business Combination), and (iii) the content of regulations and other guidance from the U.S. Department of the Treasury. In addition, because the excise tax would be payable by the Company, and not by the redeeming holder, the mechanics of any required payment of the excise tax have not been determined. The foregoing could cause a reduction in the cash available on hand to complete a Business Combination. For the year ended December 31, 2023 and 2022, the Company has recognized $3,184,272 and $0, respectively, in excise tax payable related to share redemptions. In accordance with ASC 340-10-S99-1, the liability does not impact the consolidated statements of operations and is offset against additional paid-in capital or accumulated deficit if additional paid-in capital is not available. Net (Loss) Income Per Common Share The Company has two classes of shares, which are referred to as redeemable Class A common stock and non-redeemable Class A and Class B common stock. Earnings and losses are shared pro rata between the two classes of stock. For purposes of computing diluted earnings per share, the weighted-average shares outstanding of common stock reflects the dilutive effect that could occur if convertible securities or other contracts to issue common stock were converted into or exercised for common stock as of the beginning of the period in which the conditions were satisfied (or as of the date of the contingent stock agreement, if later). The calculation of diluted net (loss) income per share does not consider the effect of the warrants issued in connection with the (i) IPO, (ii) exercise of over-allotment (iii) Private Placement and (iv) Sponsor Loans since the warrants are contingently convertible. The warrants (including warrants issuable in conjunction with the Sponsor Loans) are exercisable to purchase 33,550,000 shares of Class A common stock in the aggregate. At December 31, 2023 and 2022, the Company did not have any other dilutive securities and other contracts that could, potentially, be exercised or converted into common stock and then share in the earnings of the Company. When applying the two-class method for determining net income per share, the Company has elected to exclude remeasurement associated with the redeemable shares of Class A common stock to redemption value as the redemption amount is not in excess of fair value. Net (loss) income per common share is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 ​ 2022 ​ ​ ​ ​ Non- ​ ​ ​ Non- ​ ​ ​ ​ Redeemable ​ ​ ​ Redeemable ​ ​ Redeemable ​ Class A and ​ Redeemable ​ Class A and ​ Class A Class B Class A Class B Basic and diluted net (loss) income per share ​ ​ ​ ​ ​ ​ ​ ​ Numerator: ​ ​ ​ ​ ​ ​ ​ ​ Allocation of net (loss) income ​ $ (1,247,339) ​ $ (748,415) ​ $ 19,405,027 ​ $ 4,851,257 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares outstanding ​ 14,374,778 ​ ​ 8,625,000 ​ ​ 34,500,000 ​ ​ 8,625,000 Basic and diluted net (loss) income per share ​ $ (0.09) ​ $ (0.09) ​ $ 0.56 ​ $ 0.56 ​ Non-Redemption Agreements In April 2023, the Sponsor and certain investors (“NRA Investors”) of the Company’s Class A common stock entered into Non-Redemption Agreements. The Non-Redemption Agreements provide for the assignment of economic interest of an aggregate of 999,665 shares of Class B common stock of the Company held by the Sponsor to the Investors in exchange for such Investors agreeing to hold and not redeem their Class A common stock at the special meeting of stockholders held on May 4, 2023. Pursuant to the Non-Redemption Agreements, the Sponsor has agreed to transfer to such Investors an aggregate of 999,665 shares of Class B common stock upon the consummation of an initial Business Combination. In November 2023, the Sponsor and the holders of the founder shares converted an aggregate of 8,624,999 shares of Class B common stock to shares of Class A common stock. The Company estimated the aggregate fair value of the shares attributable to the April 2023 Non-Redemption Agreements to be $884,554 or $0.88 per share. In November 2023, the Company and the Sponsor entered into Non-Redemption Agreements with a number of the Company’s stockholders in exchange for them agreeing not to redeem shares of the Company’s Class A common stock sold in the IPO in connection with the special meeting of stockholders called by the Company and held on November 7, 2023. In exchange for the foregoing commitments not to redeem such shares, the Company has agreed to allocate to such investors an aggregate of 781,961 Promote Shares and the Sponsor has agreed to surrender and forfeit to the Company for no consideration a number of shares of Class B common stock equal to the number of Promote Shares upon closing of an initial business combination. The Company estimated the aggregate fair value of the shares attributable to the November 2023 Non-Redemption Agreements to be $6,096,756 or $7.80 per share. The Company complies with the requirements of SEC Staff Accounting Bulletin (“SAB”) Topic 5(A) – “Expenses of Offering” and SAB Topic 5(T): Miscellaneous Accounting - Accounting for Expenses or Liabilities Paid by Principal Stockholder(s). As such, the value of Promote Shares assigned to the Investors are recognized as offering costs and charged to stockholders’ deficit. The value of the Class B common stock to be forfeited by the Sponsors is reported as an increase to stockholders’ deficit. Recent Accounting Pronouncements In August 2020, the FASB issued Accounting Standards Update (“ASU”) No. 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging --Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU 2020-06”), which simplifies accounting for convertible instruments by removing major separation models required under current GAAP. The ASU also removes certain settlement conditions that are required for equity-linked contracts to qualify for the derivative scope exception, and it simplifies the diluted earnings per share calculation in certain areas. The provisions of ASU 2020-06 are applicable for fiscal years beginning after December 15, 2023, with early adoption permitted no earlier than fiscal years beginning after December 15, 2020. The Company does not believe adoption of ASU 2020-06 on January 1, 2024 will have a significant impact on its consolidated financial statements. The Company’s management does not believe that any other recently issued, but not yet effective, accounting standards if currently adopted would have a material effect on the accompanying consolidated financial statements.

RELATED PARTY TRANSACTIONS_2_3

RELATED PARTY TRANSACTIONS	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS	14. Related Party Transactions A summary of balances and transactions with the related parties who are stockholders of the Company were as follows as of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 December 31, 2023 ​ ​ Anapass Kyeongho Lee ​ Anapass Kyeongho Lee Borrowings ​ $ 9,653 ​ $ 824 ​ $ 10,082 ​ $ 1,474 Other current liabilities ​ 106 ​ 87 ​ 212 ​ 182 ​ For each of the three months ended March 31, 2024 and 2023, the Company recorded $0.1 million of interest expense with Anapass, Inc. in the condensed consolidated statements of operations. During the three months ended March 31, 2024 and 2023, the Company recorded $22,000 and $26,000, respectively, of interest expense with Kyeongho Lee in the condensed consolidated statements of operations.	12. Related Party Transactions A summary of balances and transactions with the related parties who are stockholders of the Company as of and for the years ended December 31, 2023 and 2022, are approximately as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ 2023 ​ 2022 ​ Anapass Kyeongho Lee Anapass Kyeongho Lee Borrowings ​ $ 10,082 ​ $ 1,474 ​ $ 10,257 ​ $ 1,690 Other current liabilities ​ 212 ​ 182 ​ 11 ​ 150 Interest expense ​ 548 ​ 110 ​ 389 ​ 140 ​
CONCORD ACQUISITION CORP III
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS		NOTE 3. RELATED PARTY TRANSACTIONS Founder Shares On March 1, 2021, the Sponsor paid $25,000 in exchange for 7,187,500 shares of Class B common stock (the “Founder Shares”). On March 25, 2021, the Sponsor transferred an aggregate of 75,000 Founder Shares to three members of the board of directors (each received 25,000 Founder Shares). The number of Founder Shares outstanding was determined based on the expectation that the total size of the Initial Public Offering would be a maximum of 28,750,000 Units if the underwriters’ over-allotment option is exercised in full, and therefore that such Founder Shares would represent 20% of the outstanding shares after the Initial Public Offering. On November 4, 2021, the Company’s board of directors approved the issuance of 1,437,500 additional shares of Class B common stock in the form of a stock dividend, resulting in an aggregate of 8,625,000 Class B common shares outstanding. At November 8, 2021, the total number of Class B common shares outstanding have been adjusted to reflect the issuance of the additional shares. The number of Founder Shares outstanding was adjusted based on the Initial Public Offering of 34,500,000 Units such that the Founder Shares would represent 20% of the outstanding shares after the Initial Public Offering. The issuance of 1,437,500 additional shares of Class B common stock in the form of a stock dividend was retroactively reflected for all applicable prior periods. On November 16, 2023, the holders of the Company’s Class B common stock, par value $0.0001 per share, converted 8,624,999 shares of the Company’s Class B The Company’s initial stockholders, officers and directors have agreed not to transfer, assign or sell, except to permitted transferees, any Founder Shares or Converted Shares held by them until the earlier to occur of: (1) one year after the completion of the initial Business Combination; and (2) subsequent to the initial Business Combination, (x) the date on which the Company completes a liquidation, merger, stock exchange, reorganization or other similar transaction that results in all of the public stockholders having the right to exchange their shares of common stock for cash, securities or other property or (y) if the last reported sale price of the Class A common stock equals or exceeds $12.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading day period commencing at least 150 days after the initial Business Combination. Any permitted transferees would be subject to the same restrictions and other agreements of the initial stockholders with respect to any Founder Shares or Converted Shares (the “Lock-up”). Promissory Note — Related Party On May 3, 2022, the Sponsor agreed to loan Concord III up to $350,000 to be used to pay operating expenses. This loan was non-interest bearing, unsecured, was not convertible into Warrants or any other securities, and was due at the Closing. At December 31, 2023, there was $35,000 related to the loan outstanding which was fully paid back on the Closing Date. Sponsor Loans The Company executed promissory notes with the Sponsors, evidencing loans to the Company in the aggregate amount of $6,900,000. The Sponsor Loans were extended in order to ensure that the amount in the Trust Account is $10.20 per public share upon completion of the IPO with the proceeds of the Sponsor Loans being added to the Trust Account. The Sponsor Loans are non-interest bearing with the principal balance to be repaid or converted into warrants at a conversion price of $1.00 per warrant, at the Sponsors’ discretion. All accrued and unpaid principal of the Sponsor Loans that is not converted into warrants shall continue to remain outstanding and to be subject to the terms and conditions of the Sponsor Loans and will become payable on the date the initial Business Combination is completed. If converted, the Sponsor Loan Warrants would be identical to the Private Placement Warrants. If the Company does not complete an initial Business Combination, the Company will not repay the Sponsor Loans from amounts held in the Trust Account, and its proceeds will be distributed to the Company’s public stockholders. See Note 6 for additional information. On November 2, 2023, the Company, GCT and the Sponsor entered into a Sponsor Support Agreement. Pursuant to the Sponsor Support Agreement, the Sponsor agreed to forgive all amounts outstanding under the Sponsor Loans upon the closing of the proposed Business Combination which was determined to be a modification of the Sponsor Loan. The Company follows the guidance of ASC Topic 470-50 “Debt—Modifications and Extinguishments,” for loan modifications. The Company’s Sponsor continues to maintain an equity interest in the Company. The Company determined that after accounting for the modification of the Sponsor Loan, the cash flows of the Sponsor Loan were substantially different and as such should be accounted for as an extinguishment of the original debt and the recognition of new debt. As such, the Company recognized a gain on extinguishment of the Sponsor Loans in the Company’s consolidated changes in stockholders’ equity calculated as the difference between the fair value of the Sponsor Loan under the original Sponsor Loan Agreement and the fair value of the Sponsor Loan under the updated terms of the Sponsor Support Agreement on the date of the extinguishment. During the year ended December 31, 2023, the Company recognized a gain of $2,343,000 from the changes in the fair value of the Sponsor loans in the consolidated statements of operations before the extinguishment event, and $3,343,000 related to the extinguishment of the Sponsor Loans in its consolidated statement of stockholders’ deficit. Related Party Loans In order to finance transaction costs in connection with an intended initial Business Combination, the Sponsors, an affiliate of the Sponsors or certain of the Company’s officers and directors may, but are not obligated to, loan the Company funds as may be required (the “Working Capital Loans”). If the Company completes an initial Business Combination, the Company would repay such loaned amounts out of the proceeds of the Trust Account released to the Company. Otherwise, such loans would be repaid only out of funds held outside the Trust Account. In the event that the initial Business Combination does not close, the Company may use a portion of the working capital held outside the Trust Account to repay such loaned amounts but no proceeds from the Trust Account would be used to repay such loaned amounts. Up to $1,500,000 of such loans may be convertible into Private Placement Warrants of the post Business Combination entity, at a price of $1.00 per warrant at the option of the lender. The warrants would be identical to the Private Placement Warrants issued to the Sponsors. As of December 31, 2023 and 2022, no such Working Capital Loans were outstanding. Administrative Service Fee The Company has agreed to pay an affiliate of its Sponsor a total of $20,000 per month for office space, utilities and secretarial and administrative support. Upon completion of the Company’s Business Combination or its liquidation, the Company will cease paying these monthly fees. Additionally, as described in Note 2, GCT has agreed to reimburse the Company for the administrative service fee incurred after the execution date of the Business Combination Agreement. The aggregate administrative service fee for the year ended December 31, 2023 was $240,000 . The Company has recognized an expense of $220,000 for the administrative service fee, net of $20,000 for the amount reimbursed by GCT for the year ended December 31, 2023. For the year ended December 31, 2022, the Company recognized $240,000 for the administrative service fee. For the administrative service fee, as of December 31, 2023 and 2022, the Company had $100,000 and $0 , respectively, reported on the consolidated balance sheet and included in due to related party. Due to Related Party In the normal course of business, certain expenses of the Company may be paid by, and then reimbursed to an affiliate of the Sponsor. As of December 31, 2023 and 2022, the Company had an outstanding balance due to the affiliate of the Sponsor of $100,920 and $10,024 , respectively, including the administrative service fee discussed above. The amount is included in due to related party on the consolidated balance sheets and includes but is not limited to legal expense, expense related to identifying a target business, and other expenses.

COMMITMENTS AND CONTINGENCIES_7

COMMITMENTS AND CONTINGENCIES	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	8. Commitments and Contingencies Litigation The Company is subject to various claims arising in the ordinary course of business. Although no assurance can be given, the Company believes that it is not a party to any litigation of which the outcome, if determined adversely, would individually, or in the aggregate, be reasonably expected to have a material adverse effect on the business, consolidated operating results, cash flows or financial position of the Company as of March 31, 2024. Third parties have from time to time claimed, and others may claim in the future, that the Company has infringed their past, current or future intellectual property rights. These claims, whether meritorious or not, could be time consuming, result in costly litigation, require expensive changes in the Company’s methods of doing business or could require the Company to enter into costly royalty or licensing agreements, if available. As a result, these claims could harm the Company’s business, consolidated operating results, cash flows, and financial position. Purchase Commitment The Company has certain commitments for outstanding purchase orders related to the manufacture of certain wafers utilized by the Company and other services that, once the wafers are placed into production, are noncancelable. Otherwise, these production agreements are cancellable at any time with the Company required to pay all costs incurred through the cancellation date. However, the Company has rarely cancelled these agreements once production has started. As of March 31, 2024, the Company had no outstanding noncancelable purchase commitments for these production agreements. In July 2020, the Company entered into a research and development agreement with Samsung Electronics Co., Ltd (“Samsung”). According to the agreement, the Company would design 5G chip products and Samsung would provide development and intellectual property support, mass production set up support including mask sets for manufacturing and engineering sample chip supply to the Company for a specific product. The total fee amount for the research and development (“R&D”) services pursuant to the agreement was $21.1 million. The Company bore the risk of R&D failure and was obligated to pay the $21.1 million total fee based on milestones defined in the agreement, of which $11.7 million was due based on development milestones and $9.4 million of additional NRE (“non-recurring engineering”) was to be paid within a maximum of 4 years In February 2024, the Company and Alpha Holdings Co., Ltd. (“Alpha”) entered into a foundry product development agreement related to 5G chip development for a total fee of $7.6 million. The Company bears the risk of R&D failure and is obligated to pay the fee based on milestones defined in the agreement. The Company recognizes R&D expenses based on an estimate of the percentage completion of services provided by Alpha during the respective financial reporting period. For the three months ended March 31, 2024, the Company recorded $3.5 million in R&D expenses related to services provided by Alpha. The aggregate unpaid amount related to this agreement is $5.0 million as of March 31, 2024. Assets Pledged as Collateral The Company has provided collateral to Anapass, Inc., a related party (see Note 14), for borrowings from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. in the amount of $6.7 million, $6.8 million and $9.7 million, respectively, as of March 31, 2024, and $7.0 million, $7.1 million and $10.1 million, respectively, as of December 31, 2023 (see Note 7). The following table includes a summary of the collateral provided to Anapass, Inc. (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, Secured ​ ​ 2024 ​ 2023 ​ Creditor Cash and cash equivalents ​ $ 16,122 ​ $ 254 ​ ​ Accounts receivable ​ ​ 5,118 ​ ​ 4,920 ​ Inventory ​ 1,784 ​ 1,486 Anapass, Inc. Property and equipment ​ 1,988 ​ 352 Intangible assets and others ​ 187 ​ 199 ​	5. Commitments and Contingencies ​ Litigation The Company is subject to various claims arising in the ordinary course of business. Although no assurance can be given, the Company believes that it is not presently a party to any litigation of which the outcome, if determined adversely, would individually, or in the aggregate, be reasonably expected to have a material adverse effect on the business, consolidated operating results, cash flows or financial position of the Company. Third parties have from time to time claimed, and others may claim in the future, that the Company has infringed their past, current or future intellectual property rights. These claims, whether meritorious or not, could be time consuming, result in costly litigation, require expensive changes in the Company’s methods of doing business or could require the Company to enter into costly royalty or licensing agreements, if available. As a result, these claims could harm the Company’s business, consolidated operating results, cash flows and financial position. Purchase Commitment The Company has certain commitments for outstanding purchase orders related to the manufacture of certain wafers utilized by the Company and other services that, once the wafers are placed into production, are noncancelable. Otherwise, these production agreements are cancellable at any time with the Company required to pay all costs incurred through the cancellation date. However, the Company has rarely cancelled these agreements once production has started. As of December 31, 2023 and 2022, the Company had outstanding noncancelable purchase commitments for these production agreements of $0 and $0.5 million, respectively. The Company entered into a research and development agreement with Samsung Electronics Co., Ltd (“Samsung”) in July 2020. According to the agreement, the Company designs 5G chip products and Samsung provides development and intellectual property support, mass production set up support including mask sets for manufacturing and engineering sample chip supply to the Company. Total fee amount of the agreement is $21.1 million composed of $11.7 million to be paid over development milestones and $9.4 million of additional NRE (non-recurring engineering) to be paid within maximum 4 years after planned product first shipment date. The Company bears the risk of R&D failure and is obligated to pay the fees based on milestones defined in the agreement. Pursuant to ASC 730-20, Research and Development, the Company expensed $0.4 million and $7.1 million related to this agreement for the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023 and 2022, $15.8 million and $15.4 million, respectively, of unpaid recorded expenses were included in accounts payable on the consolidated balance sheets. The aggregated unpaid amount on this agreement is $17.1 million as of December 31, 2023. Assets Pledged as Collateral The Company has provided collateral to Anapass, Inc., a related party, for borrowings of GCT R&D, a subsidiary of GCT, from KEB Hana Bank, IBK Industrial Bank and Anapass, Inc. in the amount of $7.0 million, $7.1 million and $10.1 million, respectively, as of December 31, 2023, and $7.1 million, $7.3 million and $10.3 million, respectively, as of December 31, 2022 (see Note 4). 5. Commitments and Contingencies, Assets Pledged as Collateral, Details of collateral provided to Anapass, Inc. are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) December 31, December 31, Secured ​ ​ 2023 ​ 2022 ​ Creditor Cash and cash equivalents ​ $ 254 ​ $ 1,363 Accounts receivable ​ 4,920 ​ 4,453 Inventory ​ 1,486 ​ 3,480 Anapass, Inc. Property and equipment ​ 352 ​ 485 Intangible assets and others ​ 199 ​ 531 ​
CONCORD ACQUISITION CORP III
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES		NOTE 4. COMMITMENTS AND CONTINGENCIES Registration Rights The holders of the Founder Shares, Private Placement Warrants and warrants that may be issued upon conversion of Sponsor Loans or Working Capital Loans (and any shares of common stock issuable upon the exercise of the Private Placement Warrants or warrants issued upon conversion of the Sponsor Loans or Working Capital Loans and upon conversion of the Founder Shares) will be entitled to registration rights pursuant to a registration rights agreement entered into on November 3, 2021, requiring the Company to register such securities for resale (in the case of the Founder Shares, only after conversion to shares of Class A common stock). The holders of these securities will be entitled to make up to three demands, excluding short form registration demands, that the Company registers such securities. In addition, the holders have certain “piggy-back” registration rights with respect to registration statements filed subsequent to the Company’s completion of the initial Business Combination and rights to require the Company to register for resale such securities pursuant to Rule 415 under the Securities Act. The Company will bear the expenses incurred in connection with the filing of any such registration statements. The registration rights agreement does not contain liquidating damages or other cash settlement provisions resulting from delays in registering the Company’s securities. Deferred Underwriters’ Commission The Company agreed to pay the underwriters a deferred underwriting fee upon the consummation of an initial Business Combination in an amount equal to 3.5% of the gross proceeds of the IPO, or $12,075,000. In December 2023, one of the underwriters waived any right to receive the deferred underwriters’ commission and will therefore receive no additional underwriting commissions in connection with the closing of a Business Combination. The Company considers the deferred underwriters’ commission an offering cost. Offering costs are charged to stockholders’ equity or the statement of operations based on the relative value of the Public Warrants to the proceeds received from the Units sold upon the completion of the IPO. Upon the waiver of these offering costs, a portion of these offering costs were recorded to the statement of operations and to stockholders’ equity. As a result of the waived deferred underwriters’ commission, the Company recognized $372,678 of income, $6,618,747 was recorded to accumulated deficit and the deferred underwriters’ commission was reduced by $6,991,425. Capital Markets Advisor Agreement On March 29, 2023, the Company engaged a capital markets advisor in connection with seeking an extension for completing a business combination, a possible acquisition of a third party by merger, consolidation, acquisition of stock or assets or other business combination, and as a placement agent in connection with a private placement of debt, equity, equity-linked or convertible securities. The Company agreed to pay the capital markets advisor a transaction fee in connection with the services provided, payable upon and subject to the Company’s consummation of an initial business combination (“Capital Markets Advisor Fee”). The fee consists of a fixed and determinable portion and a variable portion contingent upon certain future events expected to take place upon completion of a business combination. As of December 31, 2023, $2,500,000 was accrued under Accrued capital markets advisory expense on the consolidated balance sheet for the fee as the amount was earned and fixed and determinable. These costs may be paid for using the proceeds of the cash available once a business combination is complete. Expenses Contingent on the Closing of a Business Combination As of December 31, 2023 and 2022, the Company has incurred approximately $3,610,000 and $0, respectively, in fees contingent on the closing of a business combination, of which $2,500,000 and $0, respectively, is related to the Capital Markets Advisor Fee and $1,110,000 is related to legal fees payable contingent on a business combination. These costs may be paid using the proceeds of the cash available once a business combination is complete. The Capital Markets Advisor Fee amount is included in Accrued capital markets advisory expense and legal fees payable contingent on a business combination are included in Accrued legal expense on the consolidated balance sheets. Excise Tax In connection with the Special Meetings, stockholders holding 30,558,639 of the Company’s Public Stock exercised their right to redeem such shares for a pro rata portion of the funds in the Trust Account for an aggregate amount of $318,441,770. As such, the Company has recorded an excise tax liability of $3,184,272 on the consolidated balance sheet as of December 31, 2023. Any excise tax liability payable will not be paid out of the funds in the Trust Account. Business Combination Agreement On November 2, 2023, the Company entered into the Business Combination Agreement with GCT and Merger Sub. Pursuant to the Business Combination Agreement, the parties will consummate a business combination transaction pursuant to which Merger Sub will merge with and into GCT, with GCT surviving the merger as a wholly-owned subsidiary of the Company. See “Note 1 – Organization, Business Operations and Liquidity – Proposed Business Combination.”

STOCKHOLDERS' DEFICIT

STOCKHOLDERS' DEFICIT	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
STOCKHOLDERS' DEFICIT
STOCKHOLDERS' DEFICIT	9. Common Stock In connection with the Closing of the Business Combination, the Company increased its total number of authorized shares to 440,000,000 shares, consisting of 400,000,000 shares of common stock and 40,000,000 shares of preferred stock. The Company has reserved shares of common stock for issuance as follows (in thousands): ​ ​ ​ ​ ​ ​ March 31 December 31 ​ ​ 2024 ​ 2023 Warrants ​ 26,724 ​ 2,894 Shares available for future grant from 2024 plan ​ 3,983 ​ — Convertible promissory notes 800 1,835 Options issued and outstanding 668 668 Shares available for future grant from 2024 ESPP 600 — RSUs outstanding 392 392 Shares available for future grant from 2011 plan — 113 Total 33,167 5,902 ​	6. Common Stock The Company’s total number of authorized shares is 200,000,000 shares and the total number of common shares issued is 129,395,774 $0.001 The Company has reserved the following shares of authorized but unissued common stock as of December 31, 2023 ​ ​ ​ Options outstanding 3,579,294 RSUs outstanding 2,099,970 Shares available for grant from 2011 plan 605,826 Warrants 9,200,000 Convertible promissory notes 9,827,666 Total 25,312,756 ​
CONCORD ACQUISITION CORP III
STOCKHOLDERS' DEFICIT
STOCKHOLDERS' DEFICIT		NOTE 5. STOCKHOLDERS’ DEFICIT Preferred Stock The Company is authorized to issue a total of 1,000,000 shares of preferred stock with a par value of $0.0001 per share. At December 31, 2023 and 2022, there were no shares of preferred shares issued or outstanding. Class A Common Stock The Company is authorized to issue a total of 200,000,000 shares of Class A common stock with a par value of $0.0001 per share. Holders of Class A common stock are entitled to one vote for each share. As of December 31, 2023 and 2022, there were 8,624,999 and 0 shares of Class A common stock issued outstanding Class B Common Stock The Company is authorized to issue a total of 20,000,000 shares of Class B common stock with a par value of $0.0001 per share. Holders of the Class B common stock are entitled to one vote for each share. As of December 31, 2023 and 2022, there were 1 and 8,625,000 shares, respectively, of Class B common stock issued outstanding The Company’s initial stockholders have agreed not to transfer, assign or sell, except to permitted transferees, any of their Founder Shares or Converted Shares until the earlier to occur of: (1) one year after the completion of the initial Business Combination; and (2) subsequent to the initial Business Combination, (x) the date on which the Company completes a liquidation, merger, stock exchange, reorganization or other similar transaction that results in all of the public stockholders having the right to exchange their shares of common stock for cash, securities or other property or (y) if the last reported sale price of the Class A common stock equals or exceeds $12.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading day period commencing at least 150 days after the initial Business Combination. Any permitted transferees would be subject to the same restrictions and other agreements of the initial stockholders with respect to any Founder Shares or Converted Shares. The shares of Class B common stock will automatically convert into shares of Class A common stock at the time of the initial Business Combination on a one-for-one basis, subject to adjustment. In the case that additional shares of Class A common stock, or equity-linked securities, are issued or deemed issued in excess of the amounts offered in the Initial Public Offering and related to the closing of the initial Business Combination, the ratio at which shares of Class B common stock shall convert into shares of Class A common stock will be adjusted (unless the holders of a majority of the outstanding shares of Class B common stock agree to waive such anti-dilution adjustment with respect to any such issuance or deemed issuance) so that the number of shares of Class A common stock issuable upon conversion of all shares of Class B common stock will equal, in the aggregate, on an as-converted basis, 20% of the sum of the total number of all shares of common stock outstanding upon the completion of the Initial Public Offering (not including the Class A common stock issuable upon exercise of the Private Placement Warrants or any Sponsor Loan Warrants) plus all shares of Class A common stock and equity-linked securities issued or deemed issued in connection with the initial Business Combination (net of the number of shares of Class A common stock redeemed in connection with the initial Business Combination), excluding any shares or equity-linked securities issued, or to be issued, to any seller in the initial Business Combination. In no event shall the Class B Common Stock convert into Class A Common Stock at a ratio that is less than one-for-one. Warrants Each whole warrant entitles the holder to purchase one share of the Company’s Class A common stock at a price of $11.50 per share, subject to adjustment. The warrants will expire at 5:00 p.m., New York City time on the warrant expiration date, which is five years after the completion of the initial Business Combination or earlier upon redemption or liquidation. On the exercise of any warrant, the warrant exercise price will be paid directly to the Company and not placed in the Trust Account. The Company will not be obligated to deliver any shares of Class A common stock pursuant to the exercise of a warrant and will have no obligation to settle such warrant exercise unless a registration statement under the Securities Act covering the issuance of the shares of Class A common stock issuable upon exercise of the warrants is then effective and a current prospectus relating to those shares of Class A common stock is available, subject to the satisfying the Company’s obligations described below with respect to registration. No warrant will be exercisable for cash or on a cashless basis, and the Company will not be obligated to issue any shares to holders seeking to exercise their warrants, unless the issuance of the shares upon such exercise is registered or qualified under the securities laws of the state of the exercising holder, or an exemption from registration is available. In the event that the conditions in the two immediately preceding sentences are not satisfied with respect to a warrant, the holder of such warrant will not be entitled to exercise such warrant and such warrant may have no value and expire worthless. In no event will the Company be required to net cash settle any warrant. In the event that a registration statement is not effective for the exercised warrants, the purchaser of a unit containing such warrant will have paid the full purchase price for the unit solely for the share of Class A common stock underlying such Unit. The Company did not register the shares of Class A common stock issuable upon exercise of the warrants in connection with the IPO. However, the Company has agreed that as soon as practicable, but in no event later than 20 business days after the closing of the initial Business Combination, the Company will use its commercially reasonable efforts to file with the SEC, and within 60 Redemption of warrants when the price per share of Class A common stock equals or exceeds $18.00 . Once the warrants become exercisable, the Company may redeem the outstanding public warrants: · in whole and not in part; · at a price of $0.01 per warrant; · upon a minimum of 30 days’ prior written notice of redemption, or the 30-day redemption period, to each warrant holder; and · if, and only if, the last reported sale price of the Class A common stock equals or exceeds $18.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 Redemption of warrants when the price per share of Class A common stock equals or exceeds $10.00 . Once the warrants become exercisable, the Company may redeem the outstanding public warrants: · in whole and not in part; · at a price of $0.10 per warrant provided that holders will be able to exercise their warrants prior to redemption and receive that number of shares of Class A common stock based on the redemption date and the “fair market value” of the Class A common stock (as defined below) except as otherwise described below; · upon a minimum of 30 days’ prior written notice of redemption · if, and only if, the last reported sale price of the Class A common stock equals or exceeds $10.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) on the trading day prior to the date on which the Company sends the notice of redemption to the warrant holders; and · if, and only if, there is an effective registration statement covering the issuance of the shares of Class A common stock issuable upon exercise of the warrants and a current prospectus relating thereto available throughout the 30-day period after written notice of redemption is given. The “fair market value” of the Class A common stock shall mean the average last reported sale price of the Class A common stock for the 10 trading days ending on the third trading day prior to the date on which the notice of redemption is sent to the holders of warrants. This redemption feature differs from the typical warrant redemption features used in many other blank check offerings. In no event will the warrants be exercisable in connection with this redemption feature for more than 0.361 Class A common stock per warrant (subject to adjustment). ​ On November 2, 2023, the Company, GCT and the Sponsor entered into the Sponsor Support Agreement. Pursuant to the Sponsor Support Agreement, the Sponsor agreed to forfeit an aggregate amount of up to 2,820,000 Private Placement Warrants concurrently with the closing of the proposed Business Combination. The Company’s Private Placement Warrants are equity contracts classified as a liability. The Company follows the guidance in accordance with ASC 815-40 with this modification to the Private Placement Warrants. With the effect of the changed terms, the Company recognized a gain of $169,200 in the Company’s consolidated statement of operations.

FAIR VALUE MEASUREMENT

FAIR VALUE MEASUREMENT	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
FAIR VALUE MEASUREMENT
FAIR VALUE MEASUREMENT	5. Fair Value of Measurements Fair value hierarchy classifications of the financial instruments that are measured at fair value on a recurring basis are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 10,317 ​ $ 10,317 Warrant liabilities ​ — ​ — ​ 10,584 ​ 10,584 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ Level 1 Level 2 Level 3 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033 ​ Valuation techniques and the inputs The table below presents valuation techniques and inputs used in the fair value measurement categorized within Level 3 of the fair value hierarchy (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation techniques Inputs March 31, 2024 December 31, 2023 Convertible promissory notes, current Discounted Cash Flow Model (“DCF”) Discount rate, risk-free rate, credit spread, contractual cash flows ​ $ 5,645 ​ $ — ​ ​ PWERM (“Probability-Weighted Expected Return Method”) ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 27,794 Convertible promissory notes, net of current Binomial Lattice Model (“BLM”) Stock price, volatility, remaining term, risk-free rate, credit spread ​ $ 4,672 ​ $ — ​ ​ PWERM ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 6,239 Warrant liabilities – private and public warrants Black Scholes Merton Model (“BSM”) or BLM Exercise price, term to expiration, volatility, risk-free rate ​ $ 9,150 ​ $ — Warrant liabilities - other ​ ​ ​ ​ $ 1,434 $ — ​ As of March 31, 2024, the key inputs for the convertible promissory notes, current using the DCF were as follows: remaining term of 0.25 years and a discount rate of 10.2%. As of March 31, 2024, the key inputs for the convertible promissory notes, net of current using the BLM were as follows: stock price of $6.58, volatility of 32.2%, remaining term of 1.9 years, risk-free rate of 4.6%, and credit spread of 5.0%. As of March 31, 2024, the key inputs for the private placement warrants using the BSM were as follows: exercise price of $11.50 per share, term to expiration of 5 years, volatility range of 19.4% and a risk-free rate of 4.2%. As of March 31, 2024, the key inputs for the public warrants using the BLM were as follows: exercise price of $11.50 per share and term to expiration of 5.0 years. As of March 31, 2024, the key inputs for the warrant liabilities – other using the BSM were as follows: an exercise price of $5.00 per share, or $10.00 per share or $18.75 per share, term to expiration ranging from 0.4 years to 2.6 years, volatility ranging from 29.5% to 32.7%, and a risk-free rate ranging from 4.4% to 5.4%. As of December 31, 2023, the PWERM was used as Legacy GCT was a private company. After the Closing, and as of March 31, 2024, the valuation techniques used reflect that the Business Combination was consummated. The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Convertible promissory notes fair value - beginning of period ​ $ 34,033 ​ $ 31,166 Change in fair value of convertible promissory notes ​ 1,203 ​ (549) Conversion of convertible promissory notes ​ (41,209) ​ — Borrowing of convertible promissory notes ​ 16,290 ​ — Convertible promissory notes fair value - end of period ​ $ 10,317 ​ $ 30,617 ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Warrant Liabilities Fair value - beginning of period ​ $ — ​ $ — Private and public warrants assumed at Closing ​ 5,958 ​ — Change in fair value of warrant liabilities ​ 4,626 ​ — Warrant Liabilities Fair value - end of period ​ $ 10,584 ​ $ — ​ The gains and losses from fair value re-measurement of Level 3 financial liabilities are recorded as other income, net in the condensed consolidated statements of operations.	2. Fair Value of Measurements Fair Value Hierarchy Recurring fair value measurements Fair value hierarchy classifications of the financial instruments that are measured at fair value on a recurring basis as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2023 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 34,033 ​ $ 34,033 ​ Recurring fair value measurements, continued ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2022 (in thousands) Level 1 Level 2 Level 3 Total Convertible promissory notes ​ $ — ​ $ — ​ $ 31,166 ​ $ 31,166 ​ Valuation techniques and the inputs The table below presents valuation techniques and inputs used in the fair value measurement categorized within Level 3 of the fair value hierarchy as of December 31, 2023 and 2022. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Valuation techniques Inputs 2023 2022 Convertible promissory notes, current PWERM Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ 27,794 ​ $ 31,166 Convertible promissory notes, net of current ​ ​ ​ 6,239 ​ — ​ The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities for the years ended December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Fair value as of beginning of period ​ $ 31,166 ​ $ 56,996 Change in fair value of convertible promissory notes ​ 1,428 ​ 450 Conversion of convertible promissory notes ​ (61) ​ (33,140) Repayment of convertible promissory notes ​ (500) ​ (1,140) Transfer of convertible promissory notes to bank borrowings ​ — ​ (1,000) Borrowing of convertible promissory notes ​ 2,000 ​ 9,000 Fair value as of end of period ​ $ 34,033 ​ $ 31,166 ​ The gains and losses from fair value re-measurement of Level 3 financial liabilities are recorded as other income (expense), net in the consolidated statements of operations.
CONCORD ACQUISITION CORP III
FAIR VALUE MEASUREMENT
FAIR VALUE MEASUREMENT		NOTE 6. FAIR VALUE MEASUREMENT The following table presents fair value information as of December 31, 2023 and 2022, for the Company’s assets and liabilities that are accounted for at fair value on a recurring basis and indicates the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, Assets: Level 2023 ​ 2022 Marketable securities and in Trust Account 1 ​ $ — ​ $ 356,190,233 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, Liabilities: Level 2023 2022 Warrant Liability – Public Warrants (a) ​ $ 1,725,000 ​ $ 1,173,000 Warrant Liability – Private Placement Warrants (b) 3 ​ $ 658,000 ​ $ 639,200 Sponsor Loans 3 ​ $ — ​ $ 1,000,000 (a) Level 1 at December 31, 2023 and Level 2 at December 31, 2022 (b) At December 31, 2023, 2,820,000 Private Placement Warrants subject to forfeiture have no value as there is an assumed 100% probability of forfeiture due to the proposed Business Combination. As of December 31, 2023, cash held in the Trust Account was held in an interest-bearing demand deposit account and at December 31, 2022, investments held in Trust Account consisted of mutual funds that invest primarily in US government securities. Demand deposit accounts and mutual funds generally have a readily determinable fair value. Such investments in the Trust Account are presented on the consolidated balance sheets at fair value at the end the reporting period. The Company’s warrant liability for the Public Warrants is based on unadjusted quoted prices at the close of market. At December 31, 2022, there was insufficient trading volume for the Company’s Public Warrants to be classified as Level 1 and, as a result, were classified as Level 2. At December 31, 2023, the Company determined there was sufficient trading activity to classify its Public Warrants as Level 1. The fair value of the Company’s Private Placement Warrants (not subject to forfeiture) for all periods presented is based on a Black-Scholes-Merton model utilizing management judgment and pricing inputs from observable and unobservable markets with less volume and transaction frequency than active markets. In association with the Company’s Sponsor Support Agreement with GCT, the Sponsor agreed to forfeit up to 2,820,000 Private Placement Warrants upon the consummation of the Business Combination. For those Private Placement Warrants that became subject to forfeiture, the Company used a probability-weighted scenario analysis to value the Private Placement Warrants (subject to forfeiture) as of December 31, 2023. The change in valuation models between December 31, 2023 and December 31, 2022 was implemented as the probability-weighted scenario analysis better represents the fair value of the Private Placement Warrants that became subject to forfeiture during the year ended December 31, 2023. In association with the Company’s Sponsor Support Agreement with GCT, the Sponsor agreed to forgive all amounts outstanding under the Sponsor Loan upon the closing of the proposed Business Combination. The Company valued the Sponsor Loans using a bond plus call approach as of December 31, 2022. The bond plus call approach calculates the fair value of the Notes as the sum of (i) the fair value of the contractual cash flows of the Sponsor Loans absent the Conversion Option and (ii) the fair value of the Conversion Option which is determined using a risk-neutral framework based on the daily binomial lattice analysis. Upon forgiveness of the outstanding balance under the Sponsor Loans, the Company used a probability-weighted scenario analysis as of December 31, 2023. The change in valuation models between December 31, 2023 and December 31, 2022 was implemented as the probability-weighted scenario analysis better represents the fair value of the Sponsor Loans that were modified during the year ended December 31, 2023. The inputs used to measure fair value of the Private Placement Warrants and the Sponsor Loans are classified within Level 3 of the fair value hierarchy. Significant deviations from these estimates and inputs could result in a material change in fair value. The following table sets forth the fair value and unpaid principal balance as of December 31, 2023 and 2022 for the Sponsor Loans. ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: Fair Value Unpaid Principal Balance December 31, 2023 ​ $ — ​ $ 6,900,000 December 31, 2022 ​ $ 1,000,000 ​ $ 6,900,000 ​ The key inputs into the model for the Private Placement Warrants were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ Input 2023 2022 ​ Common stock price ​ $ 10.56 ​ $ 10.19 ​ Risk-free interest rate ​ ​ 3.81 % ​ 3.95 % Expected term in years ​ 5.25 years ​ 5.36 years Expected volatility ​ 0.00 % ​ 0.00 % Exercise price ​ $ 11.50 ​ $ 11.50 ​ Warrant fair value ​ $ 0.10 ​ $ 0.07 ​ ​ To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Because of the inherent uncertainty of valuation, those estimated values may be materially higher or lower than the values that would have been used had a ready market for the investments existed. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for investments categorized in Level 3. The following table provides a reconciliation of changes in fair value of the beginning and ending balances for our financial instruments classified as Level 3: ​ ​ ​ ​ ​ ​ ​ ​ Fair value of financial instruments classified as Level 3 ​ ​ ​ ​ ​ ​ ​ ​ Public and Private ​ ​ ​ ​ ​ Placement ​ ​ ​   ​ Warrants Sponsor Loans ​ ​ ​ ​ ​ ​ ​ January 1, 2022 ​ $ 18,655,000 ​ $ 5,490,000 Public Warrants reclassified to level 1 ​ (6,727,500) ​ Change in valuation inputs or other assumptions ​ (11,288,300) ​ (4,490,000) December 31, 2022 ​ $ 639,200 ​ 1,000,000 ​ ​ ​ ​ ​ ​ ​ January 1, 2023 ​ $ 639,200 ​ $ 1,000,000 Change in fair value of warrants subject to forfeiture ​ (191,760) ​ — Change in valuation inputs or other assumptions ​ 210,560 ​ 2,343,000 Extinguishment of debt ​ — ​ (3,343,000) December 31, 2023 ​ $ 658,000 ​ $ — ​

INCOME TAX

INCOME TAX	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
INCOME TAX
INCOME TAX	12. Income Taxes For the three months ended March 31, 2024 and 2023, the Company recorded income tax expense of $59,000 and $50,000, respectively. The effective tax rate is 7.2% and 3.7% for the three months ended March 31, 2024 and 2023, respectively. For financial reporting purposes, the Company’s effective tax rate used for the interim periods is based on the estimated full-year income tax rate. For the three months ended March 31, 2024, the Company’s effective tax rate differs from the statutory rate primarily due to the valuation allowance recorded against the net deferred tax asset balance. As of March 31, 2024 the Company had unrecognized tax benefits of $3.1 million of which $1.7 million would currently affect the Company’s effective tax rate if recognized due to the Company’s deferred tax assets being fully offset by a valuation allowance. The Company does not anticipate that the amount of unrecognized tax benefits relating to tax positions existing as of March 31, 2024 will significantly increase or decrease within the next twelve months. There was no interest expense or penalties related to unrecognized tax benefits recorded as of March 31, 2024. A number of years may elapse before an uncertain tax position is audited and finally resolved. While it is often difficult to predict the final outcome or the timing of resolution of any particular uncertain tax position, the Company believes that its reserves for income taxes reflect the most likely outcome. The Company adjusts these reserves, as well as the related interest, in light of changing facts and circumstances. Settlement of any particular position could require the use of cash. Currently the Company is not under examination by any taxing authority.	10. Income Taxes Determining the provision for income taxes, income taxes payable, and deferred tax assets and liabilities involves judgment. The Company calculates and provides for income taxes in each of the tax jurisdictions in which it operates, which involves estimating current tax exposures as well as making judgments regarding the recoverability of deferred tax assets in each jurisdiction. The estimates used could differ from actual results, and this may have a significant impact on financial position, operating results and cash flows in future periods. 10. Income Taxes, continued The domestic and foreign components of income (loss) before provision for income taxes were as follows for the years ended December 31: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Domestic ​ $ (19,910) ​ $ (30,559) Foreign ​ (2,018) ​ 4,268 Loss before provision for income taxes ​ $ (21,928) ​ $ (26,291) ​ ​ The provision for income taxes for the years ended December 31, 2023 and 2022 consisted of the following: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Current ​ ​ Federal ​ $ 215 ​ $ 128 State ​ 1 ​ 1 Foreign ​ 325 ​ (8) Total current ​ 541 ​ 121 ​ ​ ​ ​ ​ ​ ​ Deferred ​ ​ Federal ​ — ​ — State ​ — ​ — Foreign ​ — ​ — Total deferred ​ — ​ — Total provision for income taxes ​ $ 541 ​ $ 121 ​ The reconciliation of federal statutory income tax to the Company’s provision for income taxes is as follows: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Expected benefit at statutory federal rate ​ $ (4,941) ​ $ (6,717) State tax — net of federal benefit ​ 72 ​ 100 Research and development credits ​ — ​ (564) Foreign income/losses taxed at different rates ​ 14 ​ 15 Unrecognized tax benefits ​ 276 ​ 126 Stock-based compensation ​ 8 ​ 3 Interest expense ​ 333 ​ 233 Remeasurements of net defined benefit liabilities ​ 5 ​ — Exchange rate difference ​ 287 ​ 551 Change in tax rate ​ (242) ​ (92) True-up deferred taxes ​ 1,382 ​ 3,254 True-up payable ​ 75 ​ — Accumulated deficit ​ 67 ​ 10 Change in valuation allowance ​ 3,182 ​ 3,246 Other ​ 23 ​ (44) Total provision for income taxes ​ $ 541 ​ $ 121 ​ ​ 10. Income Taxes, For the years ended December 31, 2023 and 2022, the Company’s provision for income taxes differed from the federal statutory tax rate due primarily to the full valuation allowance for federal and state purposes, true-up deferred taxes, research and development credits, and exchange rate differences. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Deferred tax assets ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 79,078 ​ $ 78,583 Capitalized costs ​ 5,409 ​ 3,095 Accruals and reserves ​ 4,610 ​ 4,830 Inventory reserves ​ 267 ​ 402 Stock compensation ​ 382 ​ 368 Loss on unrealized currency translation ​ 166 ​ 160 Research and development credits ​ 2,490 ​ 2,490 Financial guarantee liabilities ​ 5,410 ​ 5,320 Lease liability ​ 197 ​ 4 Provision for credit losses ​ 368 ​ 119 Gross deferred tax assets ​ 98,377 ​ 95,371 Valuation allowance ​ (97,628) ​ (94,446) Net deferred tax assets ​ 749 ​ 925 Deferred tax liabilities ​ ​ ​ ​ ​ ​ Revaluation of convertible promissory notes ​ (448) ​ (742) Contract assets ​ (3) ​ (8) ROU assets ​ (298) ​ (175) Gross deferred tax liabilities ​ (749) ​ (925) Net deferred income tax ​ $ — ​ $ — ​ The Company provided a valuation allowance for net operating losses, credits and other deferred tax assets of its United States and foreign entities. A valuation allowance is provided when, based upon the available evidence, management concludes that it is more-likely-than-not that some portion of the deferred tax assets will not be realized. The Company maintained a valuation allowance as of December 31, 2023 and 2022 due to the uncertainty of realizing future tax benefits from its net operating loss carryforwards and other deferred tax assets. The valuation allowance increased by $3.2 million for both the years ended December 31, 2023 and 2022, respectively. The Company had net operating loss carryforwards (“NOL”) for federal, state and foreign income tax purposes of approximately $334 million, $49 million and $27 million, respectively, as of December 31, 2023. State NOL will begin to expire in 2028 and $123 million of the Company’s federal NOL will last indefinitely (limited to 80% of taxable income in a given year). As of December 31, 2023, the Company had federal and state research credit carryforwards of approximately $2.4 million and $2.3 million, respectively. The federal research credit carryforwards will begin to expire in 2025 while the California research credits carryforward have an indefinite life. ​ 10. Income Taxes, ​ Section 382 of the Internal Revenue Code of 1986, as amended, imposes restrictions on the utilization of NOL carryforwards and research tax credits in the event of a change in ownership. While the Company believes that it is probable that its ability to utilize NOL carryforwards may be limited due to past ownership changes, the Company has not yet completed an analysis to determine the amount of such limitation, if any. A reconciliation of the unrecognized tax benefits (“UTBs”) as of December 31, 2023 and 2022 is as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Beginning gross UTBs ​ $ 3,203 ​ $ 3,106 Additions for tax positions taken in a prior year ​ — ​ (35) Additions for tax provision taken in the current year ​ 319 ​ 1,093 Adjustments for tax positions for changes in currency translation ​ 95 ​ (223) Reductions for tax positions taken in the prior year ​ 1,051 ​ (270) Reductions for tax positions taken in the prior year due to statutes lapsing ​ (1,585) ​ (468) Ending gross UTBs ​ 3,083 ​ 3,203 UTBs offset by deferred tax assets and/or valuation allowance ​ (1,419) ​ (1,714) Net UTBs ​ $ 1,664 ​ $ 1,489 ​ As of December 31, 2023, the total amount of gross unrecognized tax benefits was $3.1 million. The amount of unrecognized tax benefits that, if recognized, would affect the Company’s effective tax rate is $1.7 million as of December 31, 2023. The remaining amounts in unrecognized tax benefits would not impact the rate as they are offset by valuation allowances. As of December 31, 2023 and 2022, accrued interest and penalties were $522,000 and $449,000, respectively. The Company recognizes interest and penalties related to unrecognized tax benefits within the provision for income taxes line in the accompanying consolidated statements of operations. Accrued interest and penalties are included within the related tax liability line in the consolidated balance sheets. The Company has classified the unrecognized tax benefits as long term, as it does not expect them to be realized over the next 12 months. The Company also does not expect its unrecognized tax benefits to change significantly over the next 12 months. The Company files income tax returns in the U.S. federal jurisdiction, California and in many foreign jurisdictions. The Company’s tax years for 2020 and forward are subject to examination by the U.S. tax authorities. The Company’s tax years for 2019 and forward are subject to examination by various state tax authorities. However, due to the fact that the Company had loss and credits carried forward in some jurisdictions, certain items attributable to technically closed years are still subject to adjustment by the relevant taxing authority through an adjustment to tax attributes carried forward to open years. The Company files U.S. and foreign income tax returns with varying statutes of limitations. Due to the Company’s net carryover of unused operating losses, all years remain subject to future examination by tax authorities.
CONCORD ACQUISITION CORP III
INCOME TAX
INCOME TAX		NOTE 7. INCOME TAX As of December 31, 2023 and 2022, the Company’s net deferred tax assets are as follows: ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax asset: 2023 2022 Organizational costs/startup expenses ​ $ 1,223,864 ​ $ 243,656 Federal net operating loss carryforward ​ — ​ — Total deferred tax asset ​ 1,223,864 ​ 243,656 Valuation allowance ​ (1,223,864) ​ (243,656) Deferred tax asset, net of allowance ​ $ — ​ $ — ​ The income tax provision consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ​ For the year ​ December 31, 2023 December 31, 2022 Federal: ​ ​ ​ ​ Current ​ $ 1,385,741 ​ $ 995,207 Deferred ​ ​ 980,208 ​ 172,282 ​ ​ ​ ​ ​ ​ ​ State: ​ ​ ​ ​ ​ Current ​ ​ — ​ — Deferred ​ ​ — ​ — Valuation allowance ​ ​ (980,208) ​ (172,282) Income tax provision ​ $ 1,385,741 ​ $ 995,207 ​ As of December 31, 2023 and 2022, the Company had no U.S. federal net operating loss carryovers and no state net operating loss carryovers available to offset future taxable income. In assessing the realization of the deferred tax assets, management considers whether it is more likely than not that some portion of all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which temporary differences representing net future deductible amounts become deductible. Management considers the scheduled reversal of deferred tax liabilities, if any, projected future taxable income and tax planning strategies in making this assessment. After consideration of all of the information available, management believes that significant uncertainty exists with respect to future realization of the deferred tax assets and has therefore established a full valuation allowance. For the years ended December 31, 2023 and 2022, there was an increase in the valuation allowance of $980,208 and $172,282, respectively. A reconciliation of the federal income tax rate to the Company’s effective tax rate, as a percentage of income before income taxes, is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ​ For the year ​ ​ December 31, 2023 December 31, 2022 ​ Statutory federal income tax rate ​ 21.0 % 21.0 % Transaction costs ​ 0.0 % 0.0 % Change in fair value of warrant liability and Sponsor Loans ​ (100.3) % (17.7) % Transaction costs allocated to warrants ​ 12.8 % 0.0 % Change in valuation allowance ​ (160.7) % 0.7 % Income tax provision ​ (227.2) % 4.0 % ​

SUBSEQUENT EVENTS_2_3

SUBSEQUENT EVENTS	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
SUBSEQUENT EVENTS
SUBSEQUENT EVENTS	17. Subsequent Events Purchase Agreement and Registration Rights Agreement In April 2024, the Company entered into a common stock purchase agreement (the “Purchase Agreement”) and a related registration rights agreement (the “Registration Rights Agreement”) with B. Riley Principal Capital II, LLC (“B. Riley Principal Capital II”). Upon the terms and subject to the satisfaction of the conditions set forth in the Purchase Agreement, the Company has the right, in its sole discretion, to sell to B. Riley Principal Capital II, from time to time, up to $50.0 million in aggregate gross purchase price of shares of the Company’s common stock, subject to certain limitations contained in the Purchase Agreement, during the term of 24 months M-Venture Investment, Inc. In April 2024, the Company executed an amendment with M-Venture Investment, Inc. for the KRW 4.0 billion ($3.0 million) term loan outstanding, pursuant to which the Company repaid KRW 2.0 billion ($1.5 million) in April 2024 and extended the maturity date from October 2024 to May 2024 (see Note 7). In April 2024, the Company executed an amendment with M-Venture Investment, Inc. for the KRW 6.0 billion ($4.4 million) term loan outstanding, pursuant to which the maturity date for both draws were amended. The maturity date for the principal amount of KRW 1.0 billion ($0.7 million) was extended from April 2024 to June 2024. The maturity date for the principal amount of KRW 5.0 billion ($3.7 million) was extended from April 2024 to July 2024 (see Note 7). Historical Convertible Promissory Notes In April 2024, the Company repaid in full a historical convertible promissory note that was issued in 2021 with a principal amount of $0.6 million (see Note 7). Share Reserve In May 2024, the board of directors of the Company approved 3,983,334 shares as the maximum number of shares of Common Stock that may be issued pursuant to 2024 Plan, and 600,000 shares as reserved share amount of 2024 Employee Stock Purchase Plan.	14. Subsequent Events Management has evaluated all transactions and events through March 29, 2024, the date on which these consolidated financial statements were available to be issued, and other than the following there are no other items that would adjust the consolidated financial statements or require additional disclosures. In January 2024, the maturity date of the loan of $776,000 from i Best Investment was extended for two three In January 2024, GCT R&D, a subsidiary of the Company, borrowed a short term loan of $237,000 from NJ Holdings, a related party. The loan had a seven In January, February and March 2024, GCT R&D repaid term loan of $613,000 to Kyeongho Lee. In February and March 2024, the Company issued convertible promissory notes of $11.3 million to Korean investors. The convertible promissory notes mature in February and March 2027 and have a conversion price of $6.67 per share. The convertible promissory notes will be automatically converted to common stock upon the closing of the transaction with Concord Acquisition Corp III discussed in Note 1. In February 2024, the Company issued a convertible promissory note of $5.0 million to a U.S. company. The convertible promissory note matures in February 2026 and has a conversion price of $10.00 per share. The convertible promissory note holder can demand conversion to common stock on or after the earlier of i) completion of the SPAC transaction and ii) six On March 15, 2024, the Board of Directors approved a term sheet of equity line of credit (ELOC) facility proposed by an investment banking firm. Under this facility, the Company may issue and sell shares common stock, from time to time, to an affiliate of the investment banking firm at a price equal to a specified percentage of VWAP (Volume Weighted Average Price) of the stock on NYSE up to an aggregate amount of $50 million. The term sheet is not binding and subject to completion of definitive agreements, and the Board of Directors delegated authority to the management to negotiate and finalize definitive agreements for the facility. On March 26, 2024, Concord Acquisition Corp III consummated its Business Combination with the Company, pursuant to the Business Combination Agreement, dated as of November 2, 2023, and changed name to GCT Semiconductor Holding, Inc. (“GCT Holding”). On March 26, 2024, in accordance with the terms of the Business Combination Agreement, the Company’s all outstanding warrants were assumed by GCT Holding. On March 26, 2024, the Company terminated the 2011 Plan. As a result, all outstanding options and RSUs under the 2011 Plan were assumed by GCT Holding in accordance with the terms of the Business Combination Agreement. On March 26, 2024, the convertible promissory notes (“CPN”) principal and related accrued interest balance of $32,087,000 and the convertible notes to SPAC shares (“CVT”) principal and related accrued interest balance of $13,370,000 were converted into 4,258,223 and 2,004,535 shares of GCT Holding common stock, respectively. On March 26, 2024, as consideration for the $30.2 million PIPE Financing, the Company issued 4,529,967 shares of GCT Holding common stock to PIPE Shareholders.
CONCORD ACQUISITION CORP III
SUBSEQUENT EVENTS
SUBSEQUENT EVENTS		NOTE 8. SUBSEQUENT EVENTS The Company evaluated subsequent events and transactions that occurred after the balance sheet date up to the date that the consolidated financial statements were issued. Based upon this review, other than stated below, the Company did not identify any subsequent events that would have required adjustment or disclosure in the consolidated financial statements. On February 27, 2024, the Company held a special meeting in lieu of the 2024 annual meeting of stockholders in connection with the proposed Business Combination. At the Special Meeting, the Company’s stockholders approved the Business Combination Proposal, the Charter Amendment Proposal, each of the Governance Proposals (on a non-binding advisory basis), the election of each director nominee pursuant to the Election of Directors Proposal, the Incentive Award Plan Proposal, the Employee Stock Purchase Plan Proposal, and the NYSE Proposal, in each case as defined and described in greater detail in the Final Prospectus.

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Basis of Presentation	2. Summary of Significant Accounting Policies and Basis of Presentation Principles of Consolidation and Basis of Presentation The condensed consolidated financial statements and accompanying notes include the accounts of the Company and its wholly owned subsidiaries, after elimination of intercompany balances and transactions. The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the requirements of the Securities and Exchange Commission (“SEC”) for interim financial information. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the year ended December 31, 2023, which are included in the Company’s Form 8-K filed with the SEC on April 1, 2024. The information as of December 31, 2023 included in the condensed consolidated balance sheets was derived from those audited consolidated financial statements. The unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial information. The condensed consolidated results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results to be expected for the year ending December 31, 2024 or for any other future annual or interim period. Use of Estimates The preparation of the accompanying condensed consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates, and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. These judgments, estimates and assumptions are used for but not limited to revenue recognition, provision for credit losses, inventory obsolescence, recoverability of long-lived assets, certain accrued expenses, stock-based compensation, determination of fair value of the Company’s convertible promissory notes, common stock (prior to the reverse recapitalization), warrant labilities and stock options, and deferred income taxes including related valuation allowances. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates, and these differences may be material. Fair Value of Financial Instruments The carrying amount of certain financial instruments held by the Company, such as cash equivalents, accounts receivable, contract assets and liabilities, accounts payable, and accrued and other current liabilities, approximate fair value due to their short maturities. The carrying amount of the liabilities for the convertible promissory notes represents their fair value. The carrying amounts of the Company’s bank borrowings and lease liabilities approximate fair value due to the market interest rates that these obligations bear and interest rates available to the Company. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s Level 3 financial instruments consist of convertible promissory notes and warrant liabilities. These financial instruments were valued using valuation techniques that are considered to be a Level 3 fair value measurement . Risk and Uncertainties The Company is subject to certain risks and uncertainties and believes changes in any of the following areas could have a material adverse effect on the Company’s future financial position or results of operations or cash flows: new product development, including market receptivity, the ability to satisfy obligations under development agreements with major partners, litigation or claims against the Company based on intellectual property, patent, product regulation or other factors, competition from other products, general economic conditions, the ability to attract and retain qualified employees and ultimately to sustain profitable operations. The semiconductor industry is characterized by rapid technological change, competition, competitive pricing pressures and cyclical market patterns. The Company’s financial results are affected by a wide variety of factors, such as general economic conditions specific to the semiconductor industry and the Company’s particular market, the timely implementation of new products, new manufacturing process technologies and the ability to safeguard patents and intellectual property in a rapidly evolving market. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns. As a result, the Company may experience significant period-to-period fluctuations in condensed consolidated operating results due to the factors mentioned above or other factors. The Company’s revenue may be impacted by its ability to obtain adequate wafer supplies from foundries and back-end production capacity from the Company’s test and assembly subcontractors. The foundries with which the Company currently has arrangements may not be willing or able to satisfy all of the Company’s manufacturing requirements on a timely basis and/or at favorable prices. The Company is also subject to the risks of service disruptions, raw material shortages and price increases by its foundries. Such disruptions, shortages and price increases could harm the Company’s consolidated operating results. Provision for Credit Losses The provision for credit losses is based on the Company’s assessment of the collectability of its customer accounts. The Company reviews the provision for credit losses by considering certain factors such as historical experience, industry data, credit quality, age of balances and current economic conditions that may affect a customer’s ability to pay. Uncollectible receivables are written off when all efforts to collect have been exhausted and recoveries are recognized when they are recovered. The Company determined that provisions for credit losses of approximately $1.9 million and $1.6 million were necessary as of March 31, 2024 and December 31, 2023, respectively. Concentration of Credit Risk Financial instruments that potentially subject the Company to the concentration of credit risk consist of cash and cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents primarily with one financial institution located in the United States and another financial institution located in Korea where amounts deposited may exceed Federal Deposit Insurance Corporation or Korea Deposit Insurance Corporation limits. The Company’s accounts receivable balances are primarily derived from revenues earned from customers located in the United States, China, Korea, Japan and Taiwan. The Company performs ongoing credit evaluations of its customers’ and distributors’ financial condition and generally does not require collateral from its customers. The Company’s net revenue and accounts receivable are concentrated among a few significant customers, which could expose the Company to financial risk in the event of adverse developments with these customers. Four customers accounted for approximately 28 percent, 19 percent, 18 percent and 13 percent of the Company’s gross accounts receivable as of March 31, 2024. Four customers accounted for approximately 27 percent, 19 percent, 14 percent and 10 percent of the Company’s gross accounts receivable as of December 31, 2023. Two customers accounted for approximately 61 percent and 24 percent of the Company’s total net revenues for the three months ended March 31, 2024. Four customers accounted for approximately 28 percent, 28 percent, 25 percent, and 10 percent of the Company’s total net revenues for the three months ended March 31, 2023. Management closely monitors the creditworthiness and performance of these key customers and has established credit limits and terms to mitigate potential credit risks. The Company also continues to diversify its customer base and explore opportunities to reduce its reliance on a few major customers. Foreign Currency Financial statements of foreign subsidiaries that use the local currency as their functional currency are translated into U.S. dollars at the end-of-period exchange rates or at historical exchange rates for purposes of consolidation. Revenues and expenses are translated using average exchange rates during the period. Translation adjustments are included in accumulated other comprehensive loss within stockholders’ deficit. Gains and losses resulting from transactions denominated in a currency other than the functional currency are included in other income, net in the condensed consolidated statements of operations. The Company recognized $1.1 million and $0.7 million foreign currency exchange gains for the three months ended March 31, 2024 and 2023, respectively. Convertible Promissory Notes The Company has elected the fair value option to account for its outstanding convertible promissory notes. Under the fair value option, the convertible promissory notes must be recorded at their initial fair value on the date of issuance, any modification, and at the end of each reporting period end date thereafter. Changes in the estimated fair value of the convertible promissory notes are recognized as non-cash gains or losses in other income, net in the condensed consolidated statements of operations. Contracts in Equity The Company classifies contracts in equity, including warrants to purchase shares of the Company’s common stock, that do not meet the indexation guidance as liabilities. At the end of each reporting period, such liability classified instruments are remeasured and changes in fair value during the reporting period are recognized within the condensed consolidated statements of operations until the earlier of the exercise, settlement, or expiration. The Company classifies contracts in equity, including the Legacy GCT Earnouts and Sponsor Earnouts (discussed in Note 3), that meet the indexation and equity classification guidance as a component of stockholders’ deficit and are not subject to fair value remeasurements. Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS” Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these condensed consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recent Accounting Pronouncements Adopted In August 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) Contracts in Entity’s Own Equity (Subtopic 815-40) In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805) Company adopted this guidance effective January 1, 2024, and noted no material impact on the Company’s condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820) In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740)
Principles of Consolidation		Principles of Consolidation The accompanying consolidated financial statements include the accounts of GCT and its wholly-owned subsidiaries, GCT AP, GCT R&D and MTH. All significant intercompany balances and transactions have been eliminated in consolidation.
Emerging Growth Company	Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS” Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these condensed consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.
Use of Estimates	Use of Estimates The preparation of the accompanying condensed consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates, and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. These judgments, estimates and assumptions are used for but not limited to revenue recognition, provision for credit losses, inventory obsolescence, recoverability of long-lived assets, certain accrued expenses, stock-based compensation, determination of fair value of the Company’s convertible promissory notes, common stock (prior to the reverse recapitalization), warrant labilities and stock options, and deferred income taxes including related valuation allowances. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates, and these differences may be material.	Use of Estimates The preparation of the accompanying consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates, and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. These judgments, estimates and assumptions are used for but not limited to: revenue recognition; provision for credit losses; warranty obligations; inventory obsolescence; recoverability of long-lived assets; stock-based compensation; determination of fair value of the Company’s convertible promissory notes, common stock, and stock options, and deferred income taxes including related valuation allowances. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates, and these differences may be material.
Cash and Cash Equivalents		Cash and Cash Equivalents The Company considers all highly liquid investments purchased with a remaining maturity of three months or less to be cash equivalents. The Company deposits its cash primarily in checking and money market accounts with high quality financial institutions.
Concentration of Credit Risk		Concentration of Revenues and Accounts Receivable The Company’s net revenue and accounts receivable are concentrated among a few significant customers, which could expose the Company to financial risk in the event of adverse developments with these customers. In fiscal 2023, approximately 38% of the Company’s total net revenues were derived from two customers. Moreover, approximately 70% of the total gross accounts receivable was derived from four customers at the end of the reporting period. During fiscal 2022, around 66% of the Company’s total net revenues were derived from four customers. Similar to the concentration of revenue, approximately 90% of the total gross accounts receivable was derived from five customers at the end of the reporting period. Details of external customers, who contribute more than 10% of the Company’s net revenues and gross accounts receivable as of December 31, 2023 and 2022, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Revenues ​ Accounts Receivable (in thousands) ​ 2023 ​ 2022 ​ 2023 ​ 2022 Customer A $ * $ 4,639 $ * $ 1,228 Customer B ​ 3,031 ​ 2,979 ​ 1,755 ​ 590 Customer C ​ * ​ 1,712 ​ * ​ 1,400 Customer D ​ * ​ 1,670 ​ 661 ​ 687 Customer E ​ * ​ * ​ * ​ 610 Customer F ​ * ​ * ​ 1,250 ​ * Customer G ​ 3,000 ​ * ​ * ​ * Customer H ​ * ​ * ​ 938 ​ * *Less than 10% Management closely monitors the creditworthiness and performance of these key customers and has established credit limits and terms to mitigate potential credit risks. The Company also continues to diversify its customer base and explore opportunities to reduce its reliance on a few major customers.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amount of certain financial instruments held by the Company, such as cash equivalents, accounts receivable, contract assets and liabilities, accounts payable, and accrued and other current liabilities, approximate fair value due to their short maturities. The carrying amount of the liabilities for the convertible promissory notes represents their fair value. The carrying amounts of the Company’s bank borrowings and lease liabilities approximate fair value due to the market interest rates that these obligations bear and interest rates available to the Company. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s Level 3 financial instruments consist of convertible promissory notes and warrant liabilities. These financial instruments were valued using valuation techniques that are considered to be a Level 3 fair value measurement .	Fair Value of Financial Instruments The carrying amount of certain financial instruments held by the Company, such as cash equivalents, accounts receivable, contract assets and liabilities, accounts payable, and accrued and other current liabilities, approximate fair value due to their short maturities. The carrying amount of the liabilities for the convertible promissory notes represents their fair value. The carrying amounts of the Company’s bank borrowings, and lease liabilities approximate fair value due to the market interest rates that these obligations bear and interest rates currently available to the Company. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities; Level 2 Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company has no assets with fair value obtained using observable or unobservable markets. The Company did have liabilities with a fair value obtained using unobservable markets (Level 3). The Company’s Level 3 liabilities consist of the redeemable convertible preferred stock warrant liabilities and convertible promissory notes. The convertible promissory notes were valued using a combination of option pricing model and Probability Weighted Expected Return Method (“PWERM”), which is considered to be a Level 3 fair value measurement.
Stock-Based Compensation		Stock-Based Compensation Compensation costs related to stock option grants are based on the fair value of the options on the date of grant, net of estimated forfeitures. The Company determines the grant date fair value of the options using the Black-Scholes option-pricing model and the related stock-based compensation expense is generally recognized on a straight-line basis over the period in which an employee is required to provide service in exchange for the options, which generally equals the vesting period. Compensation costs related to RSUs grants are based on the common stock price on the date of grant, net of estimated forfeitures. The related stock-based compensation expense is recognized on a straight-line basis over the vesting period of four (4) years.
Income Taxes		Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities. Valuation allowances are established when necessary to reduce deferred tax assets where, based upon the available evidence, management concludes that it is more-likely-than-not that the deferred tax assets will not be realized. The Company records a liability for the uncertain tax positions taken or expected to be taken on the Company’s tax return when it is more-likely-than-not that the tax position might be challenged despite the Company’s belief that the tax return positions are fully supportable, and additional taxes will be due as a result. To the extent that the assessment of such tax positions changes, for example, based on the outcome of a tax audit, the change in estimate is recorded in the period in which the determination is made. The provision for income taxes includes the impact of provisions for uncertain tax positions. Interest and penalties related to unrecognized tax benefits are included within the provision for income taxes.
Net (Loss) Income Per Common Share		Net Loss Per Common Share Basic net loss per common share is computed by dividing net loss attributable to common stockholders (net loss adjusted for preferred stock dividends declared or accumulated) by the weighted average number of common shares outstanding during the period. All participating securities are excluded from basic weighted average shares outstanding. In computing diluted net loss attributable to common stockholders, undistributed earnings are re-allocated to reflect the potential impact of dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing net loss attributable to common stockholders by diluted weighted average shares outstanding, including potentially dilutive securities, unless anti-dilutive. Potentially dilutive securities that were excluded from the computation of diluted net loss per common share consist of the following: ​ ​ ​ ​ ​ ​ ​ 2023 2022 Convertible promissory notes 9,827,666 9,688,740 Warrants 9,200,000 3,942,853 Options 3,579,294 4,773,892 Restricted Stock Units (RSU) 2,099,970 — Total 24,706,930 18,405,485 ​ As all potentially dilutive securities are anti-dilutive as of December 31, 2023 and 2022, diluted net loss per common share is the same as basic net loss per common share for each period.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Adopted In August 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) Contracts in Entity’s Own Equity (Subtopic 815-40) In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805) Company adopted this guidance effective January 1, 2024, and noted no material impact on the Company’s condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820) In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740)	Recent Accounting Pronouncements In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”) which significantly changes the way entities recognize impairment of many financial assets by requiring immediate recognition of estimated credit losses expected to occur over their remaining life, instead of when incurred. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments–Credit Losses, which amends Subtopic 326-20 (created by ASU 2016-13) to explicitly state that operating lease receivables are not in the scope of Subtopic 326-20. Additionally, in April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments; in May 2019, the FASB issued ASU 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief; in November 2019, the FASB issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates, and ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses; and in March 2020, the FASB issued ASU 2020-03, Codification Improvements to Financial Instruments, to provide further clarifications on certain aspects of ASU 2016-13 and to extend the nonpublic entity effective date of ASU 2016-13. The changes (as amended) are effective for the Company for annual and interim periods in fiscal years beginning after December 15, 2022. The adoption of ASU 2016-13 did not have a material effect on the consolidated financial statements. In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity. ASU 2020-06 reduces the number of accounting models for convertible instruments and allows more contracts to qualify for equity classification. ASU 2020-06 is effective for the Company’s annual reporting periods beginning after December 15, 2023. Adoption is either a modified retrospective method or a fully retrospective method of transition. Early adoption is permitted, but no earlier than annual periods beginning after December 15, 2020. The Company is currently evaluating the effect the adoption of ASU 2020-06 will have on its consolidated financial statements. In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which provides an exception to fair value measurement for contract assets and contract liabilities related to revenue contracts acquired in a business combination. The ASU requires an entity (acquirer) to recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606. At the acquisition date, an acquirer should account for the related revenue contracts in accordance with Topic 606 as if it had originated the contracts. The ASU is effective for the Company for annual and interim periods in fiscal years beginning after December 15, 2023. Early adoption is permitted. The ASU is applied to business combinations occurring on or after the effective date. The Company is currently evaluating the effect the adoption of ASU 2021-08 will have on its consolidated financial statements. In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. The ASU clarifies that a contractual restriction on the sale of an equity security should not be considered in measuring the fair value of the equity security, and also cannot be recognized as a separate unit of account. The ASU also requires the investor to disclose the fair value of equity securities subject to contractual sale restrictions, the nature and remaining duration of the restriction(s), and the circumstances that could cause a lapse in the restriction(s). The ASU is effective for the Company for annual and interim periods beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the effect the adoption of ASU 2022-03 will have on its consolidated financial statements. In September 2022, the FASB issued ASU 2022-04, Liabilities—Supplier Finance Programs (Subtopic 405-50): Disclosure of Supplier Finance Program Obligations. The ASU requires a buyer of goods and services to disclose information about its supplier finance program obligations. This ASU is effective for annual and interim periods in fiscal years beginning after December 15, 2022, except for the rollforward disclosure, which is effective for annual and interim periods in fiscal years beginning after December 15, 2023, and annual periods thereafter. The amendments in this ASU are to be applied retrospectively to each period in which a balance sheet is presented, except for the rollforward disclosure, which is to be applied prospectively. The adoption of ASU 2022-04 did not have a material effect on the consolidated financial statements. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures, which expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. The updated standard is effective for annual periods beginning in fiscal 2025 and interim periods beginning in the first quarter of fiscal 2026. Early adoption is permitted. The Company is currently evaluating the effect the adoption of ASU 2023-07 will have on its consolidated financial statements. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740) – Improvements to Income Tax Disclosures, which requires companies to disclose, on an annual basis, specific categories in the effective tax rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold. In addition, companies are required to disclose additional information about income taxes paid. The standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The standard is to be adopted on a prospective basis; however, retrospective application is permitted. The Company is currently evaluating the effect the adoption of ASU 2023-09 will have on its consolidated financial statements.
CONCORD ACQUISITION CORP III
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Basis of Presentation		Basis of Presentation The accompanying consolidated financial statements of the Company are presented in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”).
Principles of Consolidation		Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary. All intercompany transactions have been eliminated.
Reclassification		Reclassification Certain prior period amounts have been reclassified to conform to the current period presentation. The reclassification had no impact on operating costs, net, net (loss) income, earnings per share, current or total assets or liabilities, or total equity.
Emerging Growth Company		Emerging Growth Company The Company is an “emerging growth company,” as defined in Section 2(a) of the Securities Act of 1933, as amended, as modified by the Jumpstart Our Business Startups Act of 2012, (the “JOBS Act”), and it may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies including, but not limited to, not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act, reduced disclosure obligations regarding executive compensation in its periodic reports and proxy statements, and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and stockholder approval of any golden parachute payments not previously approved. Further, Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Exchange Act) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that a company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but any such election to opt out is irrevocable. The Company has elected not to opt out of such extended transition period which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company, as an emerging growth company, can adopt the new or revised standard at the time private companies adopt the new or revised standard. This may make comparison of the Company’s consolidated financial statements with another public company which is neither an emerging growth company nor an emerging growth company which has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used.
Use of Estimates		Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates.
Cash and Cash Equivalents		Cash and Cash Equivalents The Company considers all short-term investments with an original maturity of three months or less when purchased to be cash equivalents. The Company did not have any cash equivalents as of December 31, 2023 and 2022.
Expense Reimbursement Receivable from GCT		Expense Reimbursement Receivable from GCT In association with the Company’s proposed Business Combination, GCT has agreed to pay (i) all SEC and other regulatory filing fees incurred in connection with the proposed Business Combination, (ii) such expenses incurred in connection with printing, mailing, and soliciting proxies with respect to the Registration Statement and Proxy Statement, (iii) such expenses incurred in connection with any filings with or approvals from the NYSE in connection with the proposed Business Combination, including any expenses and fees incurred by the Company to maintain the minimum NYSE listing requirements, (iv) such expenses relating to the filing fees and notification requirements under the HSR Act, and (v) the SPAC Extension Expenses. As of December 31, 2023 the Company has received $413,529 for the reimbursement of expenses and offset the reported expenses by $709,970 for amounts reimbursed or reimbursable by GCT. As of December 31, 2022, no amounts were received from GCT and no expenses were offset for any expense to be incurred by GCT related to the proposed Business Combination. As of December 31, 2023 and 2022, $296,441 and $0, respectively, is due from GCT and reported on the balance sheet as expense reimbursement receivable from GCT.
Marketable Securities and Cash Held in Trust Account		Marketable Securities and Cash Held in Trust Account As of December 31, 2023 and 2022, investments held in Trust Account consisted of interest bearing demand deposits and mutual funds that invest primarily in U.S. government securities, respectively, and generally have a readily determinable fair value. Such cash and investments in mutual funds are presented on the consolidated balance sheets at fair value at the end of the reporting period. Interest, dividends, gains and losses resulting from the change in fair value of these securities are included in income from investments held in the Trust Account in the accompanying consolidated statements of operations. The estimated fair values of investments held in the Trust Account are determined using available market information. During the year ended December 31, 2022 the Trust Account held U.S. Treasury securities classified as held-to-maturity in accordance with ASC Topic 320, “Investments — Debt and Equity Securities.” Held-to-maturity securities are those securities which the Company has the ability and intent to hold until maturity. Held-to-maturity treasury securities are recorded at amortized cost on the accompanying balance sheet. A decline in the market value of held-to-maturity securities below cost that is deemed to be other than temporary, results in an impairment that reduces the carrying costs to such securities’ fair value. The impairment is charged to earnings and a new cost basis for the security is established. To determine whether an impairment is other than temporary, the Company considers whether it has the ability and intent to hold the investment until a market price recovery and considers whether evidence indicating the cost of the investment is recoverable outweighs evidence to the contrary. Evidence considered in this assessment includes the reasons for the impairment, the severity and the duration of the impairment, changes in value subsequent to year-end, forecasted performance of the investee, and the general market condition in the geographic area or industry the investee operates in. During the year ended December 31, 2022, premiums and discounts were amortized or accreted over the life of the related held-to-maturity security as an adjustment to yield using the effective-interest method. Such amortization and accretion is included in the “income from cash and investments held in Trust Account” line item in the consolidated statement of operations. Accretion of the discounts amounted to $320,030 for the year ended December 31, 2022. There were no such securities held with discounts or premiums during the year ended December 31, 2023, and as a result there was no accretion during such period.
Concentration of Credit Risk		Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist of a cash account in a financial institution, which, at times, may exceed the Federal Depository Insurance Coverage of $250,000. At December 31, 2023 and 2022, the Company has not experienced losses on this account.
Offering Costs		Offering Costs The Company complies with the requirements of ASC 340-10-S99-1 and SAB Topic 5A-“Expenses of Offering”. Offering costs consist of legal, accounting, underwriting discount and other costs that are directly related to the IPO. Accordingly, offering costs were initially charged to stockholders’ equity (consisting of underwriting discount, deferred underwriters’ commission, and other offering costs offset by offering costs attributable to the warrant liability and recorded in the statement of operations). The Company adopted the residual method to allocate the gross proceeds between Class A common stock and warrants based on their relative fair values.
Deferred Underwriters' Commission		Deferred Underwriters’ Commission The Company complies with ASC Topic 405 “Liabilities” and derecognized the deferred underwriting commission liability upon being released of the obligation by the underwriters. Upon the IPO, the Company treated the deferred underwriter’s commission as an offering cost (as discussed above). To account for the waiver of the deferred underwriting commission, the Company reduced the deferred underwriter commission liability and reversed the previously recorded cost of issuing the instruments in the IPO, which included recognizing a contra-expense in the amount previously allocated to liability classified warrants and expensed upon the IPO, and reduced the accumulated deficit and increased income available to Class B common stock, which was previously allocated to the Class A common stock subject to redemption and accretion recognized at the IPO date.
Common Stock Subject to Possible Redemption		Common Stock Subject to Possible Redemption The Company accounts for its shares of Class A common stock subject to possible redemption in accordance with the guidance in ASC Topic 480. Shares of Class A common stock subject to mandatory redemption (if any) are classified as a liability instrument and is measured at fair value. Conditionally redeemable shares of Class A common stock (including shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, shares of Class A common stock are classified as stockholders’ equity. The Company’s shares of Class A common stock feature certain redemption rights that are considered to be outside of the Company’s control and subject to the occurrence of uncertain future events. Accordingly, all shares of Class A common stock subject to possible redemption are presented at redemption value as temporary equity, outside of the stockholders’ deficit section of the Company’s balance sheet. The shares of Class A common stock sold as part of the Units in the IPO contain a redemption feature which allows for the redemption of such public shares in connection with the Company’s liquidation, if there is a shareholder vote or tender offer in connection with a Business Combination and in connection with certain amendments to the Company’s amended and restated certificate of incorporation. In accordance with the accounting treatment for redeemable equity instruments, which has been codified in ASC 480-10-S99, redemption provisions not solely within the control of the Company require Class A common stock subject to redemption to be classified outside of permanent equity. Therefore, all shares of Class A common stock have been classified outside of permanent equity. In connection with the votes to approve the Charter Amendment at the special meeting of stockholders on May 4, 2023, the holders of 30,460,066 shares of Class A common stock of the Company properly exercised their right to redeem their shares for cash at a redemption price of approximately $10.42 per share, for an aggregate redemption amount of approximately $317,000,000. In connection with the votes to approve the Second Charter Amendment at the special meeting of stockholders on November 7, 2023, the holders of an additional 98,573 shares of Class A common stock of the Company properly exercised their right to redeem their shares for cash at a redemption price of approximately $10.70 per share, for an aggregate redemption amount of approximately $1,100,000. The Company recognizes changes in redemption value immediately as they occur and adjusts the carrying value of redeemable common stock to equal the redemption value at the end of each reporting period. Increases or decreases in the carrying amount of redeemable common stock are affected by charges against additional paid-in capital (to the extent available) and accumulated deficit. For the year ended December 31, 2023 and 2022, the changes in Class A common stock subject to possible redemption are as follows: ​ ​ ​ ​ ​ ​ ​ Class A common stock subject to possible redemption ​ ​ ​ Shares ​ Amount January 1, 2022 34,500,000 ​ $ 351,900,000 Plus: ​ Increase in redemption value of shares subject to possible redemption — ​ 3,743,935 December 31, 2022 34,500,000 ​ $ 355,643,935 ​ ​ ​ ​ ​ ​ January 1, 2023 34,500,000 ​ $ 355,643,935 Plus: ​ Increase in redemption value of shares subject to possible redemption — ​ 5,209,575 Less: ​ Redemption (30,558,639) ​ (318,441,770) December 31, 2023 3,941,361 ​ $ 42,411,740
Fair Value of Financial Instruments		Fair Value of Financial Instruments The fair value of the Company’s assets and liabilities, which qualify as financial instruments under the FASB ASC 820, “Fair Value Measurement” approximates the carrying amounts represented in the balance sheets, primarily due to their short-term nature.
Fair Value Measurements		Fair Value Measurements Fair value is defined as the price that would be received for sale of an asset or paid for transfer of a liability, in an orderly transaction between market participants at the measurement date. GAAP establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). These tiers include: ● Level 1, defined as observable inputs such as quoted prices (unadjusted) for identical instruments in active markets; ● Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable such as quoted prices for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active; and ● Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions, such as valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. In some circumstances, the inputs used to measure fair value might be categorized within different levels of the fair value hierarchy. In those instances, the fair value measurement is categorized in its entirety in the fair value hierarchy based on the lowest level input that is significant to the fair value measurement.
Derivative Financial Instruments		Derivative Financial Instruments The Company evaluates its financial instruments to determine if such instruments are derivatives or contain features that qualify as embedded derivatives in accordance with ASC Topic 815, “Derivatives and Hedging”. Derivative instruments are initially recorded at fair value on the grant date and re-valued at each reporting date, with changes in the fair value reported in the statement of operations. Derivative assets and liabilities are classified in the balance sheet as current or non-current based on whether or not net-cash settlement or conversion of the instrument could be required within 12 months of the balance sheet date.
Warrant Liability		Warrant Liability The Company accounts for the 26,650,000 warrants issued in connection with the Initial Public Offering (the 17,250,000 Public Warrants and the 9,400,000 Private Placement Warrants) in accordance with the guidance contained in ASC Topic 815-40 “Contracts in Entity’s Own Equity”. Such guidance provides that because the warrants do not meet the criteria for equity classification thereunder, each warrant must be classified as a liability. Accordingly, the Company classifies each warrant as a liability at its fair value. This liability is subject to re-measurement at each balance sheet date. With each such re-measurement, the warrant liability will be adjusted to fair value, with the change in fair value recognized in the Company’s consolidated statement of operations.
Sponsor Loans		Sponsor Loans The Company has elected to account for the $6,900,000 (original principal amount) in Sponsor Loans using the fair value option in accordance with the guidance contained in ASC 825-10-25. The fair value option provides an option to elect fair value as an alternative measurement for selected financial assets, financial liabilities, unrecognized firm commitments, and written loan commitments. The Company has elected to apply the fair value option to the Sponsor Loans to simplify the accounting model applied to that class of financial instruments. See Notes 3 and 6 for additional information.
Stock-Based Compensation		Stock-Based Compensation The sale or transfers of the Founder Shares to members of the Company’s board of directors, as described in Note 5, is within the scope of FASB ASC Topic 718, “Compensation-Stock Compensation” (“ASC 718”). Under ASC 718, stock-based compensation associated with equity classified awards is measured at fair value upon the grant date. The Founder Shares were effectively sold or transferred subject to a performance condition (i.e., the occurrence of a Business Combination). Compensation expense related to the Founder Shares is recognized only when the performance condition is probable of occurrence under the applicable accounting literature in this circumstance. A business combination is not probable until it is completed. Stock-based compensation would be recognized at the date a Business Combination is considered probable in an amount equal to the number of Founder Shares times the grant date fair value per share (unless subsequently modified) less the amount initially received for the purchase of the Founder Shares. As of December 31, 2023 and for all prior periods, the Company determined that a Business Combination is not considered probable until a business combination is completed, and therefore, no stock-based compensation expense has been recognized.
Income Taxes		Income Taxes The Company accounts for income taxes under ASC 740 Income Taxes (“ASC 740”). ASC 740 requires the recognition of deferred tax assets and liabilities for both the expected impact of differences between the financial statement and tax basis of assets and liabilities and for the expected future tax benefit to be derived from tax loss and tax credit carry forwards. ASC 740 additionally requires a valuation allowance to be established when it is more likely than not that all or a portion of deferred tax assets will not be realized. The effective tax rate differs from the statutory tax rate of 21% for the year ended December 31, 2023 and 2022, primarily due to changes in fair value of the warrant liability and Sponsor Loans, which are not currently recognized in taxable income, non-deductible start-up costs, offering costs attributable to the warrants, and the valuation allowance on the deferred tax assets. ASC 740 also clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements and prescribes a recognition threshold and measurement process for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more-likely-than-not to be sustained upon examination by taxing authorities. ASC 740 also provides guidance on derecognition, classification, interest and penalties, accounting in interim period, disclosure and transition. The Company recognizes accrued interest and penalties related to unrecognized tax benefits. There were no unrecognized tax benefits and no amounts accrued for interest and penalties as of December 31, 2023 and 2022. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. The Company has identified the United States as its only “major” tax jurisdiction. The Company is subject to income tax examinations by major taxing authorities since inception. These examinations may include questioning the timing and amount of deductions, the nexus of income among various tax jurisdictions and compliance with federal and state tax laws. The Company’s management does not expect that the total amount of unrecognized tax benefits will materially change over the next twelve months. On August 16, 2022, the Inflation Reduction Act of 2022 (the “IRA”) was signed into federal law. The IRA provides for, among other things, a new U.S. federal 1% excise tax on certain repurchases (including redemptions) of stock by publicly traded U.S. corporations and certain U.S. subsidiaries of publicly traded non-U.S. corporations (each, a “covered corporation”). Because the Company is a Delaware corporation and its securities are trading on the NYSE, the Company is a “covered corporation” for this purpose. The excise tax is imposed on the repurchasing corporation itself, not its stockholders from which shares are repurchased. The amount of the excise tax is generally 1% of the fair market value of the shares repurchased at the time of the repurchase. However, for purposes of calculating the excise tax, repurchasing corporations are permitted to net the fair market value of certain new stock issuances against the fair market value of stock repurchases during the same taxable year. In addition, certain exceptions apply to the excise tax. The U.S. Department of Treasury has been given authority to provide regulations and other guidance to carry out, and prevent the abuse or avoidance of the excise tax. The IRA applies only to repurchases that occur after December 31, 2022. Any redemption or other repurchase that occurs in connection with a Business Combination may be subject to the excise tax. Whether and to what extent we would be subject to the excise tax would depend on a number of factors, including (i) the fair market value of the redemptions and repurchases in connection with a Business Combination, (ii) the timing, nature and amount of the equity issued in connection with a Business Combination (or otherwise issued not in connection with a Business Combination but issued within the same taxable year of a Business Combination), and (iii) the content of regulations and other guidance from the U.S. Department of the Treasury. In addition, because the excise tax would be payable by the Company, and not by the redeeming holder, the mechanics of any required payment of the excise tax have not been determined. The foregoing could cause a reduction in the cash available on hand to complete a Business Combination. For the year ended December 31, 2023 and 2022, the Company has recognized $3,184,272 and $0, respectively, in excise tax payable related to share redemptions. In accordance with ASC 340-10-S99-1, the liability does not impact the consolidated statements of operations and is offset against additional paid-in capital or accumulated deficit if additional paid-in capital is not available.
Net (Loss) Income Per Common Share		Net (Loss) Income Per Common Share The Company has two classes of shares, which are referred to as redeemable Class A common stock and non-redeemable Class A and Class B common stock. Earnings and losses are shared pro rata between the two classes of stock. For purposes of computing diluted earnings per share, the weighted-average shares outstanding of common stock reflects the dilutive effect that could occur if convertible securities or other contracts to issue common stock were converted into or exercised for common stock as of the beginning of the period in which the conditions were satisfied (or as of the date of the contingent stock agreement, if later). The calculation of diluted net (loss) income per share does not consider the effect of the warrants issued in connection with the (i) IPO, (ii) exercise of over-allotment (iii) Private Placement and (iv) Sponsor Loans since the warrants are contingently convertible. The warrants (including warrants issuable in conjunction with the Sponsor Loans) are exercisable to purchase 33,550,000 shares of Class A common stock in the aggregate. At December 31, 2023 and 2022, the Company did not have any other dilutive securities and other contracts that could, potentially, be exercised or converted into common stock and then share in the earnings of the Company. When applying the two-class method for determining net income per share, the Company has elected to exclude remeasurement associated with the redeemable shares of Class A common stock to redemption value as the redemption amount is not in excess of fair value. Net (loss) income per common share is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 ​ 2022 ​ ​ ​ ​ Non- ​ ​ ​ Non- ​ ​ ​ ​ Redeemable ​ ​ ​ Redeemable ​ ​ Redeemable ​ Class A and ​ Redeemable ​ Class A and ​ Class A Class B Class A Class B Basic and diluted net (loss) income per share ​ ​ ​ ​ ​ ​ ​ ​ Numerator: ​ ​ ​ ​ ​ ​ ​ ​ Allocation of net (loss) income ​ $ (1,247,339) ​ $ (748,415) ​ $ 19,405,027 ​ $ 4,851,257 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares outstanding ​ 14,374,778 ​ ​ 8,625,000 ​ ​ 34,500,000 ​ ​ 8,625,000 Basic and diluted net (loss) income per share ​ $ (0.09) ​ $ (0.09) ​ $ 0.56 ​ $ 0.56
Non-Redemption Agreements		Non-Redemption Agreements In April 2023, the Sponsor and certain investors (“NRA Investors”) of the Company’s Class A common stock entered into Non-Redemption Agreements. The Non-Redemption Agreements provide for the assignment of economic interest of an aggregate of 999,665 shares of Class B common stock of the Company held by the Sponsor to the Investors in exchange for such Investors agreeing to hold and not redeem their Class A common stock at the special meeting of stockholders held on May 4, 2023. Pursuant to the Non-Redemption Agreements, the Sponsor has agreed to transfer to such Investors an aggregate of 999,665 shares of Class B common stock upon the consummation of an initial Business Combination. In November 2023, the Sponsor and the holders of the founder shares converted an aggregate of 8,624,999 shares of Class B common stock to shares of Class A common stock. The Company estimated the aggregate fair value of the shares attributable to the April 2023 Non-Redemption Agreements to be $884,554 or $0.88 per share. In November 2023, the Company and the Sponsor entered into Non-Redemption Agreements with a number of the Company’s stockholders in exchange for them agreeing not to redeem shares of the Company’s Class A common stock sold in the IPO in connection with the special meeting of stockholders called by the Company and held on November 7, 2023. In exchange for the foregoing commitments not to redeem such shares, the Company has agreed to allocate to such investors an aggregate of 781,961 Promote Shares and the Sponsor has agreed to surrender and forfeit to the Company for no consideration a number of shares of Class B common stock equal to the number of Promote Shares upon closing of an initial business combination. The Company estimated the aggregate fair value of the shares attributable to the November 2023 Non-Redemption Agreements to be $6,096,756 or $7.80 per share. The Company complies with the requirements of SEC Staff Accounting Bulletin (“SAB”) Topic 5(A) – “Expenses of Offering” and SAB Topic 5(T): Miscellaneous Accounting - Accounting for Expenses or Liabilities Paid by Principal Stockholder(s). As such, the value of Promote Shares assigned to the Investors are recognized as offering costs and charged to stockholders’ deficit. The value of the Class B common stock to be forfeited by the Sponsors is reported as an increase to stockholders’ deficit.
Recent Accounting Pronouncements		Recent Accounting Pronouncements In August 2020, the FASB issued Accounting Standards Update (“ASU”) No. 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging --Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU 2020-06”), which simplifies accounting for convertible instruments by removing major separation models required under current GAAP. The ASU also removes certain settlement conditions that are required for equity-linked contracts to qualify for the derivative scope exception, and it simplifies the diluted earnings per share calculation in certain areas. The provisions of ASU 2020-06 are applicable for fiscal years beginning after December 15, 2023, with early adoption permitted no earlier than fiscal years beginning after December 15, 2020. The Company does not believe adoption of ASU 2020-06 on January 1, 2024 will have a significant impact on its consolidated financial statements. The Company’s management does not believe that any other recently issued, but not yet effective, accounting standards if currently adopted would have a material effect on the accompanying consolidated financial statements.

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Schedule of reconciliation of net (loss) income per common share	The following table summarizes the computation of basic and diluted net income (loss) per share (in thousands, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Numerator: ​ ​ Net income (loss), basic and diluted ​ $ 757 ​ $ (1,393) Denominator: ​ ​ Weighted-average common shares outstanding, basic ​ 25,468 ​ 23,862 Add: effect of dilutive securities ​ 789 ​ — Weighted-average common shares outstanding, diluted ​ 26,257 ​ 23,862 Net income (loss) per share, basic and diluted ​ ​ Basic ​ $ 0.03 ​ $ (0.06) Diluted ​ $ 0.03 ​ $ (0.06)
CONCORD ACQUISITION CORP III
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Schedule of changes in Class A common stock subject to possible redemption		For the year ended December 31, 2023 and 2022, the changes in Class A common stock subject to possible redemption are as follows: ​ ​ ​ ​ ​ ​ ​ Class A common stock subject to possible redemption ​ ​ ​ Shares ​ Amount January 1, 2022 34,500,000 ​ $ 351,900,000 Plus: ​ Increase in redemption value of shares subject to possible redemption — ​ 3,743,935 December 31, 2022 34,500,000 ​ $ 355,643,935 ​ ​ ​ ​ ​ ​ January 1, 2023 34,500,000 ​ $ 355,643,935 Plus: ​ Increase in redemption value of shares subject to possible redemption — ​ 5,209,575 Less: ​ Redemption (30,558,639) ​ (318,441,770) December 31, 2023 3,941,361 ​ $ 42,411,740
Schedule of reconciliation of net (loss) income per common share		​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 ​ 2022 ​ ​ ​ ​ Non- ​ ​ ​ Non- ​ ​ ​ ​ Redeemable ​ ​ ​ Redeemable ​ ​ Redeemable ​ Class A and ​ Redeemable ​ Class A and ​ Class A Class B Class A Class B Basic and diluted net (loss) income per share ​ ​ ​ ​ ​ ​ ​ ​ Numerator: ​ ​ ​ ​ ​ ​ ​ ​ Allocation of net (loss) income ​ $ (1,247,339) ​ $ (748,415) ​ $ 19,405,027 ​ $ 4,851,257 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares outstanding ​ 14,374,778 ​ ​ 8,625,000 ​ ​ 34,500,000 ​ ​ 8,625,000 Basic and diluted net (loss) income per share ​ $ (0.09) ​ $ (0.09) ​ $ 0.56 ​ $ 0.56

FAIR VALUE MEASUREMENT (Tables)

FAIR VALUE MEASUREMENT (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
FAIR VALUE MEASUREMENT
Schedule of quantitative information regarding Level 3 fair value measurements inputs	The table below presents valuation techniques and inputs used in the fair value measurement categorized within Level 3 of the fair value hierarchy (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation techniques Inputs March 31, 2024 December 31, 2023 Convertible promissory notes, current Discounted Cash Flow Model (“DCF”) Discount rate, risk-free rate, credit spread, contractual cash flows ​ $ 5,645 ​ $ — ​ ​ PWERM (“Probability-Weighted Expected Return Method”) ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 27,794 Convertible promissory notes, net of current Binomial Lattice Model (“BLM”) Stock price, volatility, remaining term, risk-free rate, credit spread ​ $ 4,672 ​ $ — ​ ​ PWERM ​ Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ — ​ $ 6,239 Warrant liabilities – private and public warrants Black Scholes Merton Model (“BSM”) or BLM Exercise price, term to expiration, volatility, risk-free rate ​ $ 9,150 ​ $ — Warrant liabilities - other ​ ​ ​ ​ $ 1,434 $ —	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Valuation techniques Inputs 2023 2022 Convertible promissory notes, current PWERM Scenario of initial public offering (“IPO”) and merger & acquisition (“M&A”) ​ $ 27,794 ​ $ 31,166 Convertible promissory notes, net of current ​ ​ ​ 6,239 ​ —
Schedule of change in the fair value of the warrant liabilities	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Convertible promissory notes fair value - beginning of period ​ $ 34,033 ​ $ 31,166 Change in fair value of convertible promissory notes ​ 1,203 ​ (549) Conversion of convertible promissory notes ​ (41,209) ​ — Borrowing of convertible promissory notes ​ 16,290 ​ — Convertible promissory notes fair value - end of period ​ $ 10,317 ​ $ 30,617 ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2024 2023 Warrant Liabilities Fair value - beginning of period ​ $ — ​ $ — Private and public warrants assumed at Closing ​ 5,958 ​ — Change in fair value of warrant liabilities ​ 4,626 ​ — Warrant Liabilities Fair value - end of period ​ $ 10,584 ​ $ —	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Fair value as of beginning of period ​ $ 31,166 ​ $ 56,996 Change in fair value of convertible promissory notes ​ 1,428 ​ 450 Conversion of convertible promissory notes ​ (61) ​ (33,140) Repayment of convertible promissory notes ​ (500) ​ (1,140) Transfer of convertible promissory notes to bank borrowings ​ — ​ (1,000) Borrowing of convertible promissory notes ​ 2,000 ​ 9,000 Fair value as of end of period ​ $ 34,033 ​ $ 31,166
CONCORD ACQUISITION CORP III
FAIR VALUE MEASUREMENT
Schedule of assets measured on fair value on a recurring basis		​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, Assets: Level 2023 ​ 2022 Marketable securities and in Trust Account 1 ​ $ — ​ $ 356,190,233
Schedule of liabilities measured on fair value on a recurring basis		​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, Liabilities: Level 2023 2022 Warrant Liability – Public Warrants (a) ​ $ 1,725,000 ​ $ 1,173,000 Warrant Liability – Private Placement Warrants (b) 3 ​ $ 658,000 ​ $ 639,200 Sponsor Loans 3 ​ $ — ​ $ 1,000,000 (a) Level 1 at December 31, 2023 and Level 2 at December 31, 2022 (b) At December 31, 2023, 2,820,000 Private Placement Warrants subject to forfeiture have no value as there is an assumed 100% probability of forfeiture due to the proposed Business Combination.
Schedule of fair value option		​ ​ ​ ​ ​ ​ ​ ​ Liabilities: Fair Value Unpaid Principal Balance December 31, 2023 ​ $ — ​ $ 6,900,000 December 31, 2022 ​ $ 1,000,000 ​ $ 6,900,000 ​
Schedule of quantitative information regarding Level 3 fair value measurements inputs		​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ Input 2023 2022 ​ Common stock price ​ $ 10.56 ​ $ 10.19 ​ Risk-free interest rate ​ ​ 3.81 % ​ 3.95 % Expected term in years ​ 5.25 years ​ 5.36 years Expected volatility ​ 0.00 % ​ 0.00 % Exercise price ​ $ 11.50 ​ $ 11.50 ​ Warrant fair value ​ $ 0.10 ​ $ 0.07 ​
Schedule of change in the fair value of the warrant liabilities		​ ​ ​ ​ ​ ​ ​ ​ Fair value of financial instruments classified as Level 3 ​ ​ ​ ​ ​ ​ ​ ​ Public and Private ​ ​ ​ ​ ​ Placement ​ ​ ​   ​ Warrants Sponsor Loans ​ ​ ​ ​ ​ ​ ​ January 1, 2022 ​ $ 18,655,000 ​ $ 5,490,000 Public Warrants reclassified to level 1 ​ (6,727,500) ​ Change in valuation inputs or other assumptions ​ (11,288,300) ​ (4,490,000) December 31, 2022 ​ $ 639,200 ​ 1,000,000 ​ ​ ​ ​ ​ ​ ​ January 1, 2023 ​ $ 639,200 ​ $ 1,000,000 Change in fair value of warrants subject to forfeiture ​ (191,760) ​ — Change in valuation inputs or other assumptions ​ 210,560 ​ 2,343,000 Extinguishment of debt ​ — ​ (3,343,000) December 31, 2023 ​ $ 658,000 ​ $ — ​

INCOME TAX (Tables)

INCOME TAX (Tables)	12 Months Ended
	Dec. 31, 2023
INCOME TAX
Schedule of net deferred tax assets	​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Deferred tax assets ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 79,078 ​ $ 78,583 Capitalized costs ​ 5,409 ​ 3,095 Accruals and reserves ​ 4,610 ​ 4,830 Inventory reserves ​ 267 ​ 402 Stock compensation ​ 382 ​ 368 Loss on unrealized currency translation ​ 166 ​ 160 Research and development credits ​ 2,490 ​ 2,490 Financial guarantee liabilities ​ 5,410 ​ 5,320 Lease liability ​ 197 ​ 4 Provision for credit losses ​ 368 ​ 119 Gross deferred tax assets ​ 98,377 ​ 95,371 Valuation allowance ​ (97,628) ​ (94,446) Net deferred tax assets ​ 749 ​ 925 Deferred tax liabilities ​ ​ ​ ​ ​ ​ Revaluation of convertible promissory notes ​ (448) ​ (742) Contract assets ​ (3) ​ (8) ROU assets ​ (298) ​ (175) Gross deferred tax liabilities ​ (749) ​ (925) Net deferred income tax ​ $ — ​ $ —
Schedule of income tax provision	The provision for income taxes for the years ended December 31, 2023 and 2022 consisted of the following: ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Current ​ ​ Federal ​ $ 215 ​ $ 128 State ​ 1 ​ 1 Foreign ​ 325 ​ (8) Total current ​ 541 ​ 121 ​ ​ ​ ​ ​ ​ ​ Deferred ​ ​ Federal ​ — ​ — State ​ — ​ — Foreign ​ — ​ — Total deferred ​ — ​ — Total provision for income taxes ​ $ 541 ​ $ 121
Schedule of federal income tax rate to effective tax rate	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2023 2022 Expected benefit at statutory federal rate ​ $ (4,941) ​ $ (6,717) State tax — net of federal benefit ​ 72 ​ 100 Research and development credits ​ — ​ (564) Foreign income/losses taxed at different rates ​ 14 ​ 15 Unrecognized tax benefits ​ 276 ​ 126 Stock-based compensation ​ 8 ​ 3 Interest expense ​ 333 ​ 233 Remeasurements of net defined benefit liabilities ​ 5 ​ — Exchange rate difference ​ 287 ​ 551 Change in tax rate ​ (242) ​ (92) True-up deferred taxes ​ 1,382 ​ 3,254 True-up payable ​ 75 ​ — Accumulated deficit ​ 67 ​ 10 Change in valuation allowance ​ 3,182 ​ 3,246 Other ​ 23 ​ (44) Total provision for income taxes ​ $ 541 ​ $ 121
CONCORD ACQUISITION CORP III
INCOME TAX
Schedule of net deferred tax assets	​ ​ ​ ​ ​ ​ ​ ​ Deferred tax asset: 2023 2022 Organizational costs/startup expenses ​ $ 1,223,864 ​ $ 243,656 Federal net operating loss carryforward ​ — ​ — Total deferred tax asset ​ 1,223,864 ​ 243,656 Valuation allowance ​ (1,223,864) ​ (243,656) Deferred tax asset, net of allowance ​ $ — ​ $ —
Schedule of income tax provision	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ​ For the year ​ December 31, 2023 December 31, 2022 Federal: ​ ​ ​ ​ Current ​ $ 1,385,741 ​ $ 995,207 Deferred ​ ​ 980,208 ​ 172,282 ​ ​ ​ ​ ​ ​ ​ State: ​ ​ ​ ​ ​ Current ​ ​ — ​ — Deferred ​ ​ — ​ — Valuation allowance ​ ​ (980,208) ​ (172,282) Income tax provision ​ $ 1,385,741 ​ $ 995,207
Schedule of federal income tax rate to effective tax rate	​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ​ For the year ​ ​ December 31, 2023 December 31, 2022 ​ Statutory federal income tax rate ​ 21.0 % 21.0 % Transaction costs ​ 0.0 % 0.0 % Change in fair value of warrant liability and Sponsor Loans ​ (100.3) % (17.7) % Transaction costs allocated to warrants ​ 12.8 % 0.0 % Change in valuation allowance ​ (160.7) % 0.7 % Income tax provision ​ (227.2) % 4.0 % ​

ORGANIZATION, BUSINESS OPERAT_2

ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY (Details)								1 Months Ended	12 Months Ended
	Mar. 26, 2024 shares	Jan. 19, 2024 item	Nov. 16, 2023 $ / shares shares	Nov. 07, 2023 USD ($) $ / shares shares	Nov. 02, 2023 USD ($) D $ / shares shares	May 04, 2023 USD ($) $ / shares shares	Nov. 08, 2021 USD ($) $ / shares shares	Apr. 30, 2023 $ / shares shares	Dec. 31, 2023 USD ($) D $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Mar. 31, 2024 USD ($) $ / shares shares	May 03, 2022 USD ($)	Dec. 31, 2021 shares
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Promissory note - related party									$ 108,000	$ 76,000	$ 72,000
Conversion price | $ / shares									$ 3.50
Common stock, par value (in dollars per share) | $ / shares									$ 0.0001	$ 0.0001	$ 0.0001
Common stock subject to possible redemption shares outstanding | shares													73,259,663
Shares agreed to sell | shares									5,902,000		33,167,000
Cash									$ 258,000	$ 1,398,000	$ 16,122,000
CONCORD ACQUISITION CORP III
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Condition for future business combination number of businesses minimum									1
Purchase price, per unit | $ / shares							$ 10		$ 10.20
Proceeds received from initial public offering, gross							$ 345,000,000
Aggregate amount									$ 6,900,000
Promissory note - related party									$ 35,000
Conversion price | $ / shares									$ 1
Condition for future business combination use of proceeds percentage									80
Condition for future business combination threshold percentage ownership									50
Obligation to redeem public shares if entity does not complete a business combination (as a percent)									100%
Redemption of shares calculated based on business days prior to consummation of business combination (in days)									2 days
Aggregate of shares | shares								999,665
Stockholders of number of shares who exercised their right to redeem shares | shares	3,766,000								30,558,639
Redemption price per share | $ / shares				$ 10.70		$ 10.42
Aggregate redemption amount				$ 1,100,000		$ 317,000,000
Trust Account				$ 42,200,000
Common stock subject to possible redemption shares outstanding | shares				3,941,361
Deferred underwriters commission									$ 6,991,425
Gross proceeds									$ 5,083,575	12,075,000
Maximum threshold period for registration statement to become effective after business combination					60 days
Percentage of gross proceeds on total equity proceeds					60
Redemption period upon closure									10 days
Maximum allowed dissolution expenses									$ 100,000
Cash									16,371	521,149
Payment for dissolution expenses									100,000
Marketable securities and cash held in Trust Account						$ 42,000,000			42,406,594	356,190,233
Net proceeds from ipo, private placement and sponsor loans									351,900,000
Cash withdrawn from trust account to pay taxes									$ 2,137,351	822,658
Holders of number of shares who exercised their right to redeem shares | shares	3,766,000								30,558,639
Reimbursement of expenses									$ 413,529	0
Offset reported expenses									709,970	0
Expense reimbursement receivable									296,441	$ 0
CONCORD ACQUISITION CORP III | Subsequent Events
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Minimum stockholders on a continuous basis | item		300
CONCORD ACQUISITION CORP III | Volume weighted average price [Member]
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Aggregate of shares | shares					20,000,000
CONCORD ACQUISITION CORP III | VWAP greater or equals to 12.50
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Unvested shares upon completion of business combination | shares					6,666,667
Stock price trigger to transfer, assign or sell any shares or warrants of the company, after the completion of the initial business combination (in dollars per share) | $ / shares					$ 12.50
Threshold trading days for transfer, assign or sale of shares or warrants, after the completion of the initial business combination | D					20
Threshold consecutive trading days for transfer, assign or sale of shares or warrants, after the completion of the initial business combination | D					30
CONCORD ACQUISITION CORP III | VWAP greater or equals to 15.00
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Unvested shares upon completion of business combination | shares					6,666,666
Stock price trigger to transfer, assign or sell any shares or warrants of the company, after the completion of the initial business combination (in dollars per share) | $ / shares					$ 15
CONCORD ACQUISITION CORP III | VWAP greater or equals to 17.50
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Unvested shares upon completion of business combination | shares					6,666,667
Stock price trigger to transfer, assign or sell any shares or warrants of the company, after the completion of the initial business combination (in dollars per share) | $ / shares					$ 17.50
CONCORD ACQUISITION CORP III | Promissory Note with Related Party
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Aggregate amount												$ 350,000
Promissory note - related party									$ 35,000
CONCORD ACQUISITION CORP III | Class B common stock
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Common stock, par value (in dollars per share) | $ / shares			$ 0.0001					$ 0.0001	$ 0.0001	$ 0.0001
Stock price trigger to transfer, assign or sell any shares or warrants of the company, after the completion of the initial business combination (in dollars per share) | $ / shares									$ 12
Threshold trading days for transfer, assign or sale of shares or warrants, after the completion of the initial business combination | D									20
Threshold consecutive trading days for transfer, assign or sale of shares or warrants, after the completion of the initial business combination | D									30
Conversion of Class B common stock to Class A common stock (in shares) | shares			8,624,999
CONCORD ACQUISITION CORP III | Class A common stock
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Sale of private placement warrants (in shares) | shares									33,550,000
Common stock, par value (in dollars per share) | $ / shares			$ 0.0001						$ 0.0001	$ 0.0001
Stockholders of number of shares who exercised their right to redeem shares | shares				98,573		30,460,066
Issue price per share | $ / shares					$ 9.20
Adjustment of exercise price of warrants based on market value and newly issued price (as a percent)					115
Conversion of Class B common stock to Class A common stock (in shares) | shares			8,624,999
Holders of number of shares who exercised their right to redeem shares | shares				98,573		30,460,066
CONCORD ACQUISITION CORP III | Class A common stock subject to possible redemption
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Common stock subject to possible redemption shares outstanding | shares									3,941,361	34,500,000
CONCORD ACQUISITION CORP III | Warrants | Class A common stock
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Purchase price, per unit | $ / shares									$ 11.50
CONCORD ACQUISITION CORP III | Public Warrants
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Stock price trigger for redemption of public warrants (in dollars per share) | $ / shares					$ 18
Adjustment one of redemption price of stock based on market value and newly issued price (as a percent)					180%
CONCORD ACQUISITION CORP III | Sponsor Loan Warrants
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Number of shares to be issued at closing | shares					1,399,107
CONCORD ACQUISITION CORP III | Initial Public Offering
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Number of units issued | shares							34,500,000
Purchase price, per unit | $ / shares									$ 10.76
Gross proceeds									$ 5,083,575
CONCORD ACQUISITION CORP III | Private Placement | Class A common stock
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Shares agreed to sell | shares					4,484,854
CONCORD ACQUISITION CORP III | Private Placement | Class A common stock | PIPE Subscription Agreement
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Purchase price per share | $ / shares					$ 6.67
Aggregate purchase price					$ 29,900,000
Aggregate number of shares agreed to allocate by Sponsor | shares					781,961
CONCORD ACQUISITION CORP III | Private Placement | Private Placement Warrants
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Price of warrant | $ / shares							$ 1
Proceeds from issuance of private placement warrants							$ 9,400,000
CONCORD ACQUISITION CORP III | Over-allotment option
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Number of units issued | shares							4,500,000
CONCORD ACQUISITION CORP III | Sponsor Earnout Shares [Member]
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Proceeds from issuance of private placement warrants					$ 169,200
Aggregate transaction consideration share price | $ / shares					$ 10
Company value amount					$ 350,000,000
Number of shares to be unvested and subject to forfeiture as of the closing to certain earn-out shares | shares					1,920,375
Number of shares to be private placement warrants issued at closing | shares					2,820,000				2,820,000
CONCORD ACQUISITION CORP III | Sponsor | Sponsor Loan Warrants
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Aggregate amount							$ 6,900,000
Conversion price | $ / shares							$ 1
CONCORD ACQUISITION CORP III | Sponsor | Initial Public Offering
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Aggregate amount									$ 6,900,000
CONCORD ACQUISITION CORP III | Sponsor | Private Placement | Private Placement Warrants
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Sale of private placement warrants (in shares) | shares							8,260,606
CONCORD ACQUISITION CORP III | CA2 Co-Investment LLC | Private Placement | Private Placement Warrants
ORGANIZATION, BUSINESS OPERATIONS AND LIQUIDITY
Sale of private placement warrants (in shares) | shares							1,139,394

SUMMARY OF SIGNIFICANT ACCOUN_9

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($)						1 Months Ended		3 Months Ended		12 Months Ended
	Mar. 26, 2024	Nov. 16, 2023	Nov. 07, 2023	May 04, 2023	Aug. 16, 2022	Nov. 30, 2023	Apr. 30, 2023	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Unrecognized tax benefits								$ 3,100,000		$ 3,083,000	$ 3,203,000	$ 3,106,000
Unrecognized tax benefits accrued for interest and penalties										$ 522,000	$ 449,000
Anti-dilutive securities attributable to warrants (in shares)								32,267,000	3,689,000	24,706,930	18,405,485
CONCORD ACQUISITION CORP III
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Expense reimbursement receivable										$ 296,441	$ 0
Accretion of the discounts										0	$ 320,030
Federal depository insurance coverage										$ 250,000
Holders of number of shares who exercised their right to redeem shares	3,766,000									30,558,639
Redemption price per share			$ 10.70	$ 10.42
Aggregate redemption amount			$ 1,100,000	$ 317,000,000
Number of warrants issued										26,650,000
Aggregate amount										$ 6,900,000
Stock-based compensation expense										$ 0
Statutory tax rate										21%	21%
Unrecognized tax benefits										$ 0	$ 0
Unrecognized tax benefits accrued for interest and penalties											0
Inflation Reduction Act of 2022, federal excise tax rate					1%
Excise tax payable attributable to redemption of common stock										3,184,272	0
Aggregate of shares							999,665
Cash equivalents										0	0
Reimbursement of expenses										413,529	0
Offset reported expenses										709,970	$ 0
CONCORD ACQUISITION CORP III | Initial Public Offering | Sponsor
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Aggregate amount										$ 6,900,000
CONCORD ACQUISITION CORP III | Private Placement Warrants
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Number of warrants issued										9,400,000
CONCORD ACQUISITION CORP III | Public Warrants
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Number of warrants issued										17,250,000
CONCORD ACQUISITION CORP III | Class A common stock
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Holders of number of shares who exercised their right to redeem shares			98,573	30,460,066
Conversion of Class B common stock to Class A common stock (in shares)		8,624,999
CONCORD ACQUISITION CORP III | Class B common stock
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Conversion of Class B common stock to Class A common stock (in shares)		8,624,999
CONCORD ACQUISITION CORP III | Class B common stock | Sponsor | Non Redemption Agreements
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Holders of number of shares who exercised their right to redeem shares							999,665
Aggregate of shares							999,665
Aggregate number of shares agreed to allocate by Sponsor						781,961
Estimated aggregate fair value of the shares						$ 6,096,756	$ 884,554
Estimated aggregate fair value of the shares (in dollars per share)						$ 7.80	$ 0.88

SUMMARY OF SIGNIFICANT ACCOU_10

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Common Stock Subject to Possible Redemption (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Class A common stock subject to possible redemption			$ 382,288,000
Increase in redemption value of shares subject to possible redemption	$ 0	$ (2,237,000)
CONCORD ACQUISITION CORP III
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Class A common stock subject to possible redemption (Shares)	3,941,361	34,500,000	34,500,000
Class A common stock subject to possible redemption	$ 42,411,740	$ 355,643,935	$ 351,900,000
Increase in redemption value of shares subject to possible redemption	$ (5,209,575)	(3,743,935)
Decrease due to share redemption (Shares)	(30,558,639)
Decrease due to share redemption	$ (318,441,770)
CONCORD ACQUISITION CORP III | Class A common stock subject to possible redemption
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Class A common stock subject to possible redemption	$ 42,411,740	$ 355,643,935

SUMMARY OF SIGNIFICANT ACCOU_11

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Net income (loss) per common share (Details) - USD ($)	3 Months Ended				12 Months Ended
	Mar. 31, 2024		Mar. 31, 2023		Dec. 31, 2023	Dec. 31, 2022
Numerator:
Allocation of net (loss) income	$ 757,000		$ (1,393,000)		$ (22,469,000)	$ (28,649,000)
Net loss attributable to common stockholders - diluted	$ 757,000		$ (1,393,000)
Denominator:
Weighted average number of common shares used in computing net loss per common share - basic	25,468,000	[1]	23,862,000	[1]	128,459,102	92,958,570
Weighted average number of common shares used in computing net loss per common share - diluted	26,257,000	[1]	23,862,000	[1]	128,459,102	92,958,570
Net loss per common share - basic	$ 0.03	[1]	$ (0.06)	[1]	$ (0.17)	$ (0.31)
Net loss per common share - diluted	$ 0.03	[1]	$ (0.06)	[1]	$ (0.17)	$ (0.31)
CONCORD ACQUISITION CORP III | Class A common stock
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Number of warrants to purchase shares issued					33,550,000
Numerator:
Allocation of net (loss) income					$ (1,247,339)	$ 19,405,027
Denominator:
Weighted average number of common shares used in computing net loss per common share - basic					14,374,778	34,500,000
Net loss per common share - basic					$ (0.09)	$ 0.56
CONCORD ACQUISITION CORP III | Class B common stock
Numerator:
Allocation of net (loss) income					$ (748,415)	$ 4,851,257
Denominator:
Weighted average number of common shares used in computing net loss per common share - basic					8,625,000	8,625,000
Weighted average number of common shares used in computing net loss per common share - diluted					8,625,000	8,625,000
Net loss per common share - basic					$ (0.09)	$ 0.56
Net loss per common share - diluted					$ (0.09)	$ 0.56
[1] Amounts as of December 31, 2023 differ from those in prior year consolidated financial statements as they were retrospectively adjusted as a result of the accounting for the Business Combination (as defined in the Notes to the Unaudited Condensed Consolidated Financial Statements.)

RELATED PARTY TRANSACTIONS - Fo

RELATED PARTY TRANSACTIONS - Founder Shares (Details)				12 Months Ended
	Nov. 16, 2023 $ / shares shares	Nov. 04, 2021 shares	Mar. 01, 2021 USD ($) $ / shares shares	Dec. 31, 2023 $ / shares shares	Mar. 31, 2024 $ / shares shares	Mar. 26, 2024 shares	Apr. 30, 2023 $ / shares	Dec. 31, 2022 $ / shares shares	Mar. 25, 2021 director shares
RELATED PARTY TRANSACTIONS
Common stock, shares outstanding				24,166,000	45,833,000			24,166,000
Common stock, par value (in dollars per share) | $ / shares				$ 0.0001	$ 0.0001			$ 0.0001
CONCORD ACQUISITION CORP III
RELATED PARTY TRANSACTIONS
Common stock, shares outstanding						3,941,000
CONCORD ACQUISITION CORP III | Class A common stock
RELATED PARTY TRANSACTIONS
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001			$ 0.0001				$ 0.0001
Conversion of Class B common stock to Class A common stock (in shares)	8,624,999
CONCORD ACQUISITION CORP III | Class B common stock
RELATED PARTY TRANSACTIONS
Common stock, shares outstanding				1				8,625,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001			$ 0.0001			$ 0.0001	$ 0.0001
Conversion of Class B common stock to Class A common stock (in shares)	8,624,999
Restrictions on transfer period of time after business combination completion				1 year
Stock price trigger to transfer, assign or sell any shares or warrants of the company, after the completion of the initial business combination (in dollars per share) | $ / shares				$ 12
Threshold period after the business combination in which the 20 trading days within any 30 trading day period commences				150 days
CONCORD ACQUISITION CORP III | Founder Shares | Class A common stock
RELATED PARTY TRANSACTIONS
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001
Conversion of Class B common stock to Class A common stock (in shares)	8,624,999
CONCORD ACQUISITION CORP III | Founder Shares | Class B common stock
RELATED PARTY TRANSACTIONS
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001
Conversion of Class B common stock to Class A common stock (in shares)	8,624,999
CONCORD ACQUISITION CORP III | Founder Shares | Sponsor
RELATED PARTY TRANSACTIONS
Member of the board of directors | director									3
CONCORD ACQUISITION CORP III | Founder Shares | Sponsor | Class B common stock
RELATED PARTY TRANSACTIONS
Aggregate purchase price | $			$ 25,000
Common stock issued in PIPE Financing			7,187,500
Number of shares transferred (in shares)									75,000
Aggregate number of shares owned			28,750,000						25,000
Percentage of issued and outstanding shares after the Initial Public Offering collectively held by initial stockholders			20%
Share dividend		1,437,500
Common stock, shares outstanding		8,625,000
Number of units sold		34,500,000
Percentage of outstanding shares		20%
Restrictions on transfer period of time after business combination completion			1 year
Stock price trigger to transfer, assign or sell any shares or warrants of the company, after the completion of the initial business combination (in dollars per share) | $ / shares			$ 12
Threshold Trading Days Transfer Assign Or Sell Any Shares Or Warrants After Completion Of Initial Business Combination			20 days
Threshold Consecutive Trading Days Transfer Assign Or Sell Any Shares Or Warrants After Completion Of Initial Business Combination			30 days
Threshold period after the business combination in which the 20 trading days within any 30 trading day period commences			150 days

RELATED PARTY TRANSACTIONS - Ad

RELATED PARTY TRANSACTIONS - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	May 03, 2022
RELATED PARTY TRANSACTIONS
Promissory note - related party	$ 72,000		$ 108,000	$ 76,000
Conversion price			$ 3.50
Change in valuation of warrant liabilities	4,626,000
Interest to pay dissolution expenses	$ 2,082,000	$ 935,000	$ 6,246,000	3,364,000
CONCORD ACQUISITION CORP III
RELATED PARTY TRANSACTIONS
Aggregate amount			6,900,000
Promissory note - related party			$ 35,000
Extension of sponsor loans			$ 10.20
Conversion price			$ 1
Change in valuation of warrant liabilities			$ 2,913,800	(21,332,800)
Extinguishment of debt			3,343,000
CONCORD ACQUISITION CORP III | Working Capital Loans
RELATED PARTY TRANSACTIONS
Outstanding balance of related party note			0	0
CONCORD ACQUISITION CORP III | Sponsor
RELATED PARTY TRANSACTIONS
Change in valuation of warrant liabilities			2,343,000
Outstanding balance of related party note			100,920	10,024
CONCORD ACQUISITION CORP III | Promissory Note with Related Party
RELATED PARTY TRANSACTIONS
Aggregate amount					$ 350,000
Promissory note - related party			35,000
CONCORD ACQUISITION CORP III | Administrative Service Fee
RELATED PARTY TRANSACTIONS
Expenses per month			20,000
Aggregate administrative service fee			240,000	240,000
Administrative service fee			220,000
Net amount reimbursed by GCT			20,000
CONCORD ACQUISITION CORP III | Related Party Loans
RELATED PARTY TRANSACTIONS
Loan conversion agreement warrant			1,500,000
Outstanding balance of related party note			$ 100,000	$ 0
CONCORD ACQUISITION CORP III | Related Party Loans | Working Capital Loans
RELATED PARTY TRANSACTIONS
Price of warrants			$ 1

COMMITMENTS AND CONTINGENCIES_8

COMMITMENTS AND CONTINGENCIES (Details) - CONCORD ACQUISITION CORP III - USD ($)			12 Months Ended
	Mar. 26, 2024	Nov. 08, 2021	Dec. 31, 2023	Dec. 31, 2022
COMMITMENTS AND CONTINGENCIES
Amount of underwriters commission recognized			$ 372,678
Accumulated deficit			6,618,747
Underwriters commission was reduced			6,991,425
Contingent fees			3,610,000	$ 0
Accrued fees			$ 2,500,000
Stockholders of number of shares who exercised their right to redeem shares	3,766,000		30,558,639
Aggregate amount in Trust Account			$ 318,441,770
Excise tax payable			3,184,272
Capital Markets Advisor Fee
COMMITMENTS AND CONTINGENCIES
Contingent fees			2,500,000	$ 0
Legal Fees
COMMITMENTS AND CONTINGENCIES
Contingent fees			$ 1,110,000
IPO
COMMITMENTS AND CONTINGENCIES
Deferred underwriting discount (in percentage)		3.50%
Deferred underwriting discount		$ 12,075,000

STOCKHOLDERS' DEFICIT - Preferr

STOCKHOLDERS' DEFICIT - Preferred Stock (Details) - $ / shares	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
STOCKHOLDERS' DEFICIT
Preferred stock, shares authorized	40,000,000	82,352,000
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
CONCORD ACQUISITION CORP III
STOCKHOLDERS' DEFICIT
Preferred stock, shares authorized		1,000,000	1,000,000
Preferred stock, par value (in dollars per share)		$ 0.0001	$ 0.0001
Preferred stock, shares issued		0	0
Preferred stock, shares outstanding		0	0

STOCKHOLDERS' DEFICIT - Common

STOCKHOLDERS' DEFICIT - Common Stock (Details)	12 Months Ended
	Dec. 31, 2023 Vote D $ / shares shares	Mar. 31, 2024 $ / shares shares	Mar. 26, 2024 shares	Nov. 16, 2023 $ / shares	Nov. 07, 2023 shares	Apr. 30, 2023 $ / shares	Dec. 31, 2022 $ / shares shares	Dec. 31, 2021 shares
STOCKHOLDERS' DEFICIT
Common stock, shares authorized	200,000,000	400,000,000					200,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001					$ 0.0001
Common stock, shares issued	24,166,000	45,833,000	45,833,000				127,760,265
Common stock, shares outstanding	24,166,000	45,833,000					24,166,000
Class A common stock subject to possible redemption, outstanding (in shares)								73,259,663
CONCORD ACQUISITION CORP III
STOCKHOLDERS' DEFICIT
Common stock, shares outstanding			3,941,000
Class A common stock subject to possible redemption, outstanding (in shares)					3,941,361
CONCORD ACQUISITION CORP III | Class A common stock
STOCKHOLDERS' DEFICIT
Common stock, shares authorized	200,000,000						200,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001			$ 0.0001			$ 0.0001
Common stock, votes per share | Vote	1
CONCORD ACQUISITION CORP III | Class A common stock subject to possible redemption
STOCKHOLDERS' DEFICIT
Class A common stock subject to possible redemption, outstanding (in shares)	3,941,361						34,500,000
CONCORD ACQUISITION CORP III | Class A common stock not subject to possible redemption
STOCKHOLDERS' DEFICIT
Common stock, shares issued	8,624,999						0
Common stock, shares outstanding	8,624,999						0
CONCORD ACQUISITION CORP III | Class B common stock
STOCKHOLDERS' DEFICIT
Common stock, shares authorized	20,000,000						20,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001			$ 0.0001		$ 0.0001	$ 0.0001
Common stock, votes per share | Vote	1
Common stock, shares issued	1						8,625,000
Common stock, shares outstanding	1						8,625,000
Restrictions on transfer period of time after business combination completion	1 year
Threshold trading days for transfer, assign or sale of shares or warrants, after the completion of the initial business combination | D	20
Threshold consecutive trading days for transfer, assign or sale of shares or warrants, after the completion of the initial business combination | D	30
Threshold period after the business combination in which the 20 trading days within any 30 trading day period commences	150 days
Stock conversion ratio	1
Ratio to be applied to the stock in the conversion	20%
common stock equals or exceeds | $ / shares	$ 12
Conversion of stock, shares converted	8,624,299

STOCKHOLDERS' DEFICIT - Warrant

STOCKHOLDERS' DEFICIT - Warrants (Details) - CONCORD ACQUISITION CORP III		12 Months Ended
	Nov. 02, 2023 USD ($) shares	Dec. 31, 2023 D $ / shares shares	Nov. 08, 2021 $ / shares
STOCKHOLDERS' DEFICIT
Purchase price, per unit		$ 10.20	$ 10
Sponsor Earnout Shares
STOCKHOLDERS' DEFICIT
Number of shares to be private placement warrants issued at closing | shares	2,820,000	2,820,000
Gain on Warrants | $	$ 169,200
Class A common stock
STOCKHOLDERS' DEFICIT
Number of shares issuable per warrant | shares		1
Warrants
STOCKHOLDERS' DEFICIT
Threshold trading days for redemption of public warrants		20 days
Period of time within which registration statement is expected to become effective		60 days
Warrants | Class A common stock
STOCKHOLDERS' DEFICIT
Purchase price, per unit		$ 11.50
Warrants | Redemption of warrants when the price per share of Class A common stock equals or exceeds $18.00
STOCKHOLDERS' DEFICIT
Threshold trading days for redemption of public warrants		20 days
Stock price trigger for redemption of public warrants		$ 18
Redemption price per public warrant (in dollars per share)		$ 0.01
Minimum threshold written notice period for redemption of public warrants		30 days
Redemption period		30 days
Threshold number of business days before sending notice of redemption to warrant holders | D		30
Warrants | Redemption of warrants when the price per share of Class A common stock equals or exceeds $10.00
STOCKHOLDERS' DEFICIT
Stock price trigger for redemption of public warrants		$ 10
Redemption price per public warrant (in dollars per share)		$ 0.10
Redemption period		30 days
Warrant redemption condition minimum share price		$ 10
Number of trading days on which fair market value of shares is reported | D		30
Warrant exercise price adjustment multiple		0.361

FAIR VALUE MEASUREMENT (Details

FAIR VALUE MEASUREMENT (Details) - CONCORD ACQUISITION CORP III - USD ($)		12 Months Ended
	Nov. 02, 2023	Dec. 31, 2023	Dec. 31, 2022
Liabilities.:
Warrant Liability		$ 2,383,000	$ 1,812,200
Sponsor Earnout Shares
Liabilities.:
Number of shares to be private placement warrants issued at closing	2,820,000	2,820,000
Private Placement Warrants
Liabilities.:
percentage of warrants subject to forfeiture		100%
Level 1 | Recurring | Marketable Securities Held In Trust Account
Liabilities.:
Marketable securities held in Trust Account			356,190,233
Level 1 | Recurring | Public Warrants
Liabilities.:
Warrant Liability		$ 1,725,000
Level 2 | Recurring | Public Warrants
Liabilities.:
Warrant Liability			1,173,000
Level 3 | Recurring | Private Placement Warrants
Liabilities.:
Warrant Liability		$ 658,000	639,200
Level 3 | Recurring | Sponsor Loans
Liabilities.:
Warrant Liability			$ 1,000,000

FAIR VALUE MEASUREMENT - Sponso

FAIR VALUE MEASUREMENT - Sponsor Loan Measurement (Details) - CONCORD ACQUISITION CORP III - Sponsor Loans - Level 3 - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
FAIR VALUE MEASUREMENT
Fair Value		$ 1,000,000	$ 5,490,000
Unpaid Principal Balance	$ 6,900,000	$ 6,900,000

FAIR VALUE MEASUREMENT - Level

FAIR VALUE MEASUREMENT - Level 3 Fair Value Measurements Inputs (Details) - CONCORD ACQUISITION CORP III - Level 3 - Private Placement Warrants	Dec. 31, 2023 $ / shares Y	Dec. 31, 2022 $ / shares Y
Common stock price
FAIR VALUE MEASUREMENT
Fair value measurement input	10.56	10.19
Risk-free interest rate
FAIR VALUE MEASUREMENT
Fair value measurement input	0.0381	0.0395
Expected term in years
FAIR VALUE MEASUREMENT
Fair value measurement input | Y	5.25	5.36
Expected volatility
FAIR VALUE MEASUREMENT
Fair value measurement input	0	0
Exercise price
FAIR VALUE MEASUREMENT
Fair value measurement input	11.50	11.50
Warrant fair value
FAIR VALUE MEASUREMENT
Fair value measurement input	0.10	0.07

FAIR VALUE MEASUREMENT - Change

FAIR VALUE MEASUREMENT - Change in the Fair Value of the Warrant Liabilities (Details) - USD ($)	3 Months Ended		12 Months Ended		24 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023
Changes in the fair value of the warrant
Change in fair value of warrants subject to forfeiture	$ 4,626,000
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)			Interest Expense
CONCORD ACQUISITION CORP III
Changes in the fair value of the warrant
Public Warrants reclassified to level 1			$ (2,383,000)	$ (1,812,200)	$ (2,383,000)
Change in fair value of warrants subject to forfeiture			2,913,800	$ (21,332,800)
Extinguishment of debt			$ (3,343,000)
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]			Change in fair value of warrants subject to forfeiture	Change in fair value of warrants subject to forfeiture
CONCORD ACQUISITION CORP III | Public And Private Placement Warrants | Level 3
Changes in the fair value of the warrant
Fair value as of beginning of period	$ 658,000	$ 639,200	$ 639,200	$ 18,655,000	18,655,000
Public Warrants reclassified to level 1				(6,727,500)
Change in fair value of warrants subject to forfeiture			(191,760)	(11,288,300)
Change in fair value of convertible promissory notes			210,560
Fair value as of end of period			658,000	639,200	658,000
CONCORD ACQUISITION CORP III | Sponsor Loans | Level 3
Changes in the fair value of the warrant
Fair value as of beginning of period		$ 1,000,000	1,000,000	5,490,000	$ 5,490,000
Change in fair value of warrants subject to forfeiture				(4,490,000)
Change in fair value of convertible promissory notes			2,343,000
Extinguishment of debt			$ (3,343,000)
Fair value as of end of period				$ 1,000,000

INCOME TAX - Deferred tax asset

INCOME TAX - Deferred tax assets (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Components of Deferred Tax Assets [Abstract]
Gross deferred tax assets	$ 98,377,000	$ 95,371,000
Valuation allowance	(97,628,000)	(94,446,000)
Deferred tax asset, net of allowance	(749,000)	(925,000)
CONCORD ACQUISITION CORP III
Components of Deferred Tax Assets [Abstract]
Organizational costs/startup expenses	1,223,864	243,656
Federal net operating loss carryforward	0	0
Gross deferred tax assets	1,223,864	243,656
Valuation allowance	(1,223,864)	(243,656)
Deferred tax asset, net of allowance	$ 0	$ 0

INCOME TAX - Income tax benefit

INCOME TAX - Income tax benefit (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Federal:
Current			$ 215,000	$ 128,000
State:
Current			1,000	1,000
Valuation allowance			(3,200,000)	(3,200,000)
Total provision for income taxes	$ 59,000	$ 50,000	541,000	121,000
CONCORD ACQUISITION CORP III
Federal:
Current			1,385,741	995,207
Deferred			980,208	172,282
State:
Current			0	0
Deferred			0	0
Valuation allowance			(980,208)	(172,282)
Total provision for income taxes			$ 1,385,741	$ 995,207

INCOME TAX - Reconciliation of

INCOME TAX - Reconciliation of the federal income tax rate (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
INCOME TAX
Income tax provision	7.20%	3.70%
CONCORD ACQUISITION CORP III
INCOME TAX
Statutory federal income tax rate			21%	21%
Transaction costs			0%	0%
Change in fair value of warrant liability and Sponsor Loans			(100.30%)	(17.70%)
Transaction costs allocated to warrants			12.80%	0%
Change in valuation allowance			(160.70%)	0.70%
Income tax provision			(227.20%)	4%

INCOME TAX - Additional informa

INCOME TAX - Additional information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
INCOME TAX
U.S. federal net operating loss carryovers	$ 123,000,000
Change in valuation allowance	3,200,000	$ 3,200,000
CONCORD ACQUISITION CORP III
INCOME TAX
U.S. federal net operating loss carryovers	0	0
Change in valuation allowance	$ 980,208	$ 172,282