Upstart (UPST) 10-Q14 May 212021 Q1 Quarterly reportFinancial data

Company Profile

Cover Page

Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2021	May 07, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-39797
Entity Registrant Name	Upstart Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-4332431
Entity Address, Address Line One	2950 S. Delaware Street
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	San Mateo
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94403
City Area Code	650
Local Phone Number	204-1000
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	UPST
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Shell Company	false
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		76,904,178
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001647639
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Assets
Cash		$ 257,017	$ 250,819
Restricted cash		79,049	60,514
Property, equipment, and software, net		10,098	10,032
Operating lease right of use assets		17,265	18,310
Other assets (includes $6,831 and $8,734 at fair value as of December 31, 2020 and March 31, 2021, respectively)		51,937	40,046
Total assets	[1]	488,588	477,255
Liabilities:
Accounts payable		8,127	13,775
Payable to investors		56,490	45,501
Borrowings		41,891	62,626
Accrued expenses and other liabilities (includes $9,530 and $12,628 at fair value as of December 31, 2020 and March 31, 2021, respectively)		42,869	35,669
Operating lease liabilities		18,621	19,432
Total liabilities	[1]	167,998	177,003
Stockholders’ equity:
Common stock, $0.0001 par value; 700,000,000 shares authorized; 73,314,026 and 73,908,252, shares issued and outstanding as of December 31, 2020 and March 31, 2021, respectively		7	7
Additional paid-in capital		379,703	369,467
Accumulated deficit		(59,120)	(69,222)
Total stockholders’ equity		320,590	300,252
Total liabilities and stockholders’ equity		488,588	477,255
Variable Interest Entity, Primary Beneficiary
Assets
Restricted cash		19,440	12,371
Other assets (includes $6,831 and $8,734 at fair value as of December 31, 2020 and March 31, 2021, respectively)		47	29
Total assets		86,723	104,992
Liabilities:
Accounts payable		71	83
Borrowings		21,428	42,181
Accrued expenses and other liabilities (includes $9,530 and $12,628 at fair value as of December 31, 2020 and March 31, 2021, respectively)		0	32
Total liabilities		21,499	42,296
Stockholders’ equity:
Total stockholders’ equity		65,224	62,696
Loans (at fair value)
Assets
Loans, notes receivables, and residual certificates		57,189	78,460
Loans (at fair value) \| Variable Interest Entity, Primary Beneficiary
Assets
Loans, notes receivables, and residual certificates		52,558	75,373
Notes receivable and residual certificates (at fair value)
Assets
Loans, notes receivables, and residual certificates		16,033	19,074
Notes receivable and residual certificates (at fair value) \| Variable Interest Entity, Primary Beneficiary
Assets
Loans, notes receivables, and residual certificates		$ 14,678	$ 17,219

[1]	The following table presents information on assets and liabilities related to variable interest entities (“VIEs”) that are consolidated by Upstart Holdings, Inc. at December 31, 2020 and March 31, 2021. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. The holders of the beneficial interests do not have recourse to the general credit of Upstart Holdings, Inc. The assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs and exclude intercompany balances that eliminate in consolidation. December 31, March 31, 2020 2021 Assets Restricted cash $ 12,371 $ 19,440 Loans (at fair value) 75,373 52,558 Notes receivable and residual certificates (at fair value) 17,219 14,678 Other assets 29 47 Total assets $ 104,992 $ 86,723 Liabilities Accounts payable $ 83 $ 71 Borrowings 42,181 21,428 Other liabilities 32 — Total liabilities $ 42,296 $ 21,499

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Other assets at fair value	$ 8,734	$ 6,831
Accrued expenses and other liabilities at fair value	$ 12,628	$ 9,530
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	700,000,000	700,000,000
Common stock, issued (in shares)	73,908,252	73,314,026
Common Stock, outstanding (in shares)	73,908,252	73,314,026

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue:
Revenue from fees, net	$ 116,170	$ 68,013
Interest income and fair value adjustments, net (includes $608 from related parties expense and $4,335 of related parties fair value adjustments for the three months ended March 31, 2020)	5,175	(4,019)
Total revenue	121,345	63,994
Operating expenses:
Sales and marketing	49,376	35,952
Customer operations	17,388	8,811
Engineering and product development	18,988	7,018
General, administrative, and other	20,019	11,660
Total operating expenses	105,771	63,441
Income from operations	15,574	553
Other income (expense)	(5,233)	150
Income (expense) on warrants and other non-operating expenses, net	(18)	289
Net income before income taxes	10,323	992
Provision for income taxes	221	0
Net income before attribution to noncontrolling interests	10,102	992
Net loss attributable to noncontrolling interests	0	(488)
Net income attributable to Upstart Holdings, Inc. common stockholders	$ 10,102	$ 1,480
Net income per share attributable to Upstart Holdings, Inc. common stockholders, basic (in dollars per share)	$ 0.14	$ 0
Net income per share attributable to Upstart Holdings, Inc. common stockholders, diluted (in dollars per share)	$ 0.11	$ 0
Weighted-average number of shares outstanding used in computing net income per share attributable to Upstart Holdings, Inc. common stockholders, basic (in shares)	73,629,122	14,625,267
Weighted-average number of shares outstanding used in computing net income per share attributable to Upstart Holdings, Inc. common stockholders, diluted (in shares)	91,449,571	14,625,267

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations and Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Related party interest expense		$ 608
Fair value adjustments from related parties	$ 4,335

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Total	Total Upstart Holdings, Inc. Stockholders’ Deficit	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Noncontrolling Interest
Beginning balance at Dec. 31, 2019	$ 162,546
Beginning balance (in shares) at Dec. 31, 2019	47,349,577,000
Ending balance (in shares) at Mar. 31, 2020	47,349,577,000
Ending balance at Mar. 31, 2020	$ 162,546
Beginning balance at Dec. 31, 2019	(61,688)	$ (62,714)	$ 2	$ 12,489	$ (75,205)	$ 1,026
Beginning balance (in shares) at Dec. 31, 2019			14,561,398,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)			92,634,000
Issuance of common stock upon exercise of stock options	185	185		185
Stock-based compensation expense	2,055	2,055		2,055
Return of capital to interests in consolidated VIEs	(381)					(381)
Net income (loss)	992	1,480			1,480	(488)
Ending balance at Mar. 31, 2020	(58,837)	(58,994)	$ 2	14,729	(73,725)	157
Ending balance (in shares) at Mar. 31, 2020			14,654,032,000
Beginning balance at Dec. 31, 2020	$ 0
Beginning balance (in shares) at Dec. 31, 2020	0
Ending balance (in shares) at Mar. 31, 2021	0
Ending balance at Mar. 31, 2021	$ 0
Beginning balance at Dec. 31, 2020	$ 300,252	300,252	$ 7	369,467	(69,222)	0
Beginning balance (in shares) at Dec. 31, 2020	73,314,026		73,314,026,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	521,511,000		521,511,000
Issuance of common stock upon exercise of stock options	$ 1,492	1,492		1,492
Issuance of common stock upon settlement of restricted stock units (in shares)			308,000
Exercise of common stock warrant (in shares)	72,407		72,407,000
Stock-based compensation expense	$ 8,744	8,744		8,744
Net income (loss)	10,102	10,102			10,102
Ending balance at Mar. 31, 2021	$ 320,590	$ 320,590	$ 7	$ 379,703	$ (59,120)	$ 0
Ending balance (in shares) at Mar. 31, 2021	73,908,252		73,908,252,000

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
Condensed Consolidated Statements of Cash Flows - USD ($)	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net income (loss)	$ 10,102,000	$ 992,000
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Change in fair value of financial instruments (includes $(4,335) to related parties for the three months ended March 31, 2020)	901,000	11,995,000
Stock-based compensation	8,622,000	1,965,000
Gain (loss) on loan servicing arrangements and sale of noncontrolling interests, net	67,000	(1,459,000)
Depreciation and amortization	816,000	515,000
Noncash interest expense	18,000	18,000
Net changes in operating assets and liabilities:
Purchase of loans for immediate resale to investors	(1,294,634,000)	(848,540,000)
Proceeds from immediate resale of loans to investors	1,294,634,000	848,540,000
Purchase of loans held-for-sale	(18,240,000)	(97,924,000)
Principal payments received for loans held-for-sale	2,637,000	2,328,000
Net proceeds from sale of loans held-for-sale	38,140,000	6,813,000
Other assets	(9,988,000)	(202,000)
Operating lease liability and right-of-use asset	234,000	37,000
Accounts payable	(5,807,000)	(3,003,000)
Payable to investors	10,989,000	570,000
Accrued expenses and other liabilities	4,601,000	(9,167,000)
Net cash (used in) provided by operating activities	43,092,000	(86,522,000)
Cash flows from investing activities
Principal payments received for loans held by consolidated securitizations	0	15,273,000
Net proceeds from sale of loans held-for-investment	8,329,000	88,136,000
Principal payments received for loans held-for-investment	3,002,000	5,429,000
Principal payments received for notes receivable and repayments of residual certificates	3,119,000	4,028,000
Purchase of loans held-for-investment	(12,947,000)	(2,755,000)
Purchase of notes receivable and residual certificates	0	(4,000)
Purchase of property and equipment	(267,000)	(508,000)
Capitalized software costs	(334,000)	(858,000)
Net cash provided by investing activities	902,000	108,741,000
Cash flows from financing activities
Payments made on securitization notes and certificates (includes $633 paid to related parties for the three months ended March 31, 2020)	0	(16,740,000)
Repayments of borrowings	(26,584,000)	(78,011,000)
Distributions made to noncontrolling interests	0	(381,000)
Proceeds from borrowings	5,831,000	64,839,000
Proceeds from exercise of stock options	1,492,000	185,000
Net cash used in financing activities	(19,261,000)	(30,108,000)
Net increase (decrease) in cash and restricted cash	24,733,000	(7,889,000)
Cash and restricted cash
Beginning of period	311,333,000	80,067,000
End of period	336,066,000	72,178,000
Supplemental disclosures of cash flow information
Cash paid for interest	1,030,000	3,256,000
Supplemental disclosures of non-cash investing and financing activities
Capitalized stock-based compensation expense	$ 122,000	$ 90,000

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows (Parenthetical)	3 Months Ended
	Mar. 31, 2021USD ($)
Change in fair value of financial instruments	$ (901,000)
Payments made on securitization notes and certificates	0
Affiliate
Change in fair value of financial instruments	(4,335,000)
Payments made on securitization notes and certificates	$ 633,000

Description of Business and Sig

Description of Business and Significant Accounting Policies	3 Months Ended
Description of Business and Significant Accounting Policies	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Significant Accounting Policies	Description of Business and Significant Accounting Policies Description of Business Upstart Holdings, Inc. and its subsidiaries (together “Upstart,” or the “Company”) apply modern data science and technology to the process of originating consumer credit. The Company helps bank partners originate credit by providing them with a proprietary, cloud-based, artificial intelligence lending platform. As the Company’s technology continues to improve and additional banks adopt the Upstart platform, consumers benefit from improved access to affordable and frictionless credit. Upstart Network, Inc. was incorporated in Delaware in 2012. Pursuant to a restructuring, Upstart Holdings, Inc. was incorporated in December 2013 and became the holding company of Upstart Network, Inc. The Company currently operates in the United States and is headquartered in San Mateo, California and Columbus, Ohio. The Company’s fiscal year ends on December 31. Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements included in our Annual Report on Form 10-K and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to state fairly the Company’s financial position, results of operations, comprehensive income and cash flows for the periods presented, but are not necessarily indicative of the results of operations to be anticipated of any future annual or interim periods. Certain information and disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to rules and regulations of the Securities and Exchange Commission. Accordingly, the information included in this Quarterly Report on Form 10-Q should be read in conjunction with the consolidated financial statements and accompanying notes included in our Annual Report on Form 10-K for the year ended December 31, 2020. Use of Estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires that management 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 condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions made in the accompanying condensed consolidated financial statements, which management believes are critical in understanding and evaluating the Company’s reported financial results include: (i) fair value determinations; (ii) stock-based compensation; (iii) consolidation of VIEs; and (iv) provision for income taxes, net of valuation allowance for deferred tax assets. The Company bases its estimates on various factors it believes to be reasonable under the circumstances. Actual results could differ from those estimates and such differences could affect the results of operations reported in future periods. Stock-Based Compensation The Company issues stock options and restricted stock units (“RSUs”) to employees and nonemployees, including directors and third-party service providers, and employee stock purchase rights granted under the Company’s employee stock purchase plan (“ESPP”). Stock options and employee stock purchase rights granted under the ESPP are initially measured at fair value at the date of grant using the Black-Scholes option-pricing model. RSUs are measured at the fair market value of our common stock at the grant date. Stock-based compensation expenses are recognized based on their respective grant-date fair values. Forfeitures are estimated at the time of grant and revised, as necessary, in subsequent periods if actual forfeitures differ from initial estimates. Stock-based compensation expense is recorded net of estimated forfeitures, such that the expense is recorded only for those stock options that are expected to vest. Other Income (Expense) In the three months ended March 31, 2020, other income (expense) primarily consists of dividend income earned by the Company on its unrestricted cash balance which is recognized in the period earned. In April 2020, the Company received a forgivable loan under the Paycheck Protection Program (“PPP”), totaling $5.3 million with a stated annual interest rate of 1%. All loan payments are deferred for six months if not forgiven under the provisions of the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”). The loan and accrued interest are forgivable for borrowers who use the loan proceeds for eligible expenses during a twenty-four week period following the borrower’s receipt of the loan and maintain payroll and employee headcount. The Company has used the full proceeds of the loan for eligible expenses within the required period. The Company determined that forgiveness of the loan under the CARES Act was reasonably assured and recorded the full amount of proceeds as other income in the condensed consolidated statement of operations comprehensive income in 2020. In March 2021, the Company voluntarily repaid proceeds received under the Paycheck Protection Program plus accrued interest totaling $5.3 million. The Company recognized the loan principal repayment as an other expense. Recently Adopted Accounting Pronouncements The Company adopted the following accounting standards during the three months ended March 31, 2021: In August 2018, the FASB issued ASU 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract , which requires a customer in a hosting arrangement that is a service contract to follow the internal-use software guidance in Topic 350-40 to determine which implementation costs to capitalize as assets or expense as incurred. The standard is effective January 1, 2021 for emerging growth companies that have adopted the private company relief. The amendments in this ASU can be applied either retrospectively or prospectively to all implementation costs after the date of adoption. The guidance became effective on January 1, 2021 and the Company adopted the standard on a prospective basis. The adoption of the standard did not have a material impact on the Company’s financial statements or related disclosures. In August 2020, the FASB issued ASU No. 2020-06, Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , which simplifies accounting for convertible instruments by removing major separation models required under current U.S. GAAP. The standard removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and also simplifies the diluted earnings per share calculation in certain areas The amendments in this update are effective for public business entities for fiscal years beginning after December 15, 2021, and interim periods within those fiscal years. The amendment is to be adopted through either a fully retrospective or modified retrospective method of transition. Early adoption is permitted. The Company early adopted ASU 2020-06 on January 1, 2021 with no material impact on the Company’s financial statements or related disclosures. Recently Issued Accounting Pronouncements In June 2016, the FASB amended guidance related to impairment of financial instruments as part of ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which will be effective January 1, 2023 for emerging growth companies that have adopted the private company relief. The guidance replaces the incurred loss impairment methodology with an expected credit loss model for which a company recognizes an allowance based on the estimate of expected credit loss. The Company accounts for its loans at fair value through net income, which is outside the scope of Topic 326. For available for sale debt securities, the guidance will require recognition of expected credit losses by recognizing an allowance for credit losses when the fair value of the security is below amortized cost and the recognition of this allowance is limited to the difference between the security’s amortized cost basis and fair value. The Company is evaluating the impact this ASU will have on its condensed consolidated balance sheets, condensed consolidated statements of operations and comprehensive income, condensed consolidated statements of cash flows and related disclosures. The Company plans to adopt Topic 326 effective as of January 1, 2023. In March 2020 the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting followed by and ASU 2021-01, Reference Rate Reform, Scop e issued in January 2021. ASU 2020-04 and ASU 2021-01 provide temporary optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions that reference the London Interbank Offered Rate or another reference rate expected to be discontinued because of reference rate reform, if certain criteria are met. The guidance in ASU 2020-04 and ASU 2021-01 was effective upon issuance and, once adopted, may be applied prospectively to contract modifications and hedging relationships through December 31, 2022. The Company is currently evaluating the impact of the adoption of ASU 2020-04 and ASU 2021-01 on its condensed consolidated financial statements and related disclosures.

Revenue

Revenue	3 Months Ended
Revenue	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Revenue from fees, net The Company disaggregates revenue from fees by type of service for the periods presented as follows: Three Months Ended March 31, 2020 2021 Revenue from fees, net: Platform and referral fees, net $ 60,230 $ 106,953 Servicing fees, net 7,783 9,217 Total revenue from fees, net $ 68,013 $ 116,170 Platform and referral fees, net The Company enters into contracts with bank partners to provide access to a cloud-based artificial intelligence lending platform developed by the Company (the “Upstart platform”) to enable banks to originate unsecured personal and auto refinance loans. The Upstart platform includes a cloud-based application (through Upstart.com or a bank-branded program) for submitting loan applications, verifying information provided within submitted applications, risk underwriting (through a series of proprietary technology solutions), delivery of electronic loan offers, and if the offer is accepted by the borrower, an electronic loan documentation signed by the borrower. Bank partners can specify certain parameters of loans they are willing to originate. Under these contracts, bank partners can choose to use Upstart’s referral services, which allow them to access new borrowers through Upstart’s marketing channels. The Company’s contracts with bank partners are non-cancelable and generally have 12-month terms that automatically renew. After origination, Upstart-powered loans are either retained by bank partners, purchased by the Company for immediate resale to institutional investors under loan sale agreements, or purchased and held by the Company. For loans purchased by the Company, Upstart pays bank partners a one-time loan premium fee upon completion of the minimum holding periods. Upstart also pays bank partners monthly loan trailing fees based on the amount and timing of principal and interest payments made by borrowers of the underlying loans. The monthly loan trailing fees are paid based on the amount and timing of principal and interest payments made by borrowers of the underlying loans. Both the loan premium fees and loan trailing fees are consideration payable to customers and are recorded as a reduction to platform and referral fees, net, which is part of revenue from fees, net, in the condensed consolidated statements of operations and comprehensive income for the periods presented. The Company recognized $2.4 million and $3.6 million of loan premium fees and loan trailing fees as contra-revenue within platform and referral fees, net for the three months ended March 31, 2020 and 2021, respectively. The Company started paying loan trailing fees on January 1, 2019. As of December 31, 2020 and March 31, 2021, the Company recorded $1.3 million and $1.8 million of loan trailing fee liability, respectively, which is recorded at fair value and included within accrued expenses other liabilities on the Company’s condensed consolidated balance sheets. Refer to “ Note 4. Fair Value Measurement ” for additional information on changes in fair value associated with trailing fee liabilities. The Company’s arrangements for platform and referral services typically consist of an obligation to provide one or both of these services to customers, which are our bank partners, on a when and if needed basis (a stand-ready obligation), and revenue is recognized as such services are performed. Additionally, the services have the same pattern and period of transfer, and when provided individually or together, are accounted for as a single combined performance obligation representing a series of distinct services. Platform and referral services are typically provided under a fixed or declining (tier-based) price per unit based on volume or as a percentage of the total value of loans originated each period; however, pricing for these services may also be based on minimum usage fees. The tier-based pricing, when offered, resets on a monthly basis and does not accumulate. Given that the nature of the Company’s promise is to stand ready and provide continuous access to and process transactions through the platform, tier-based pricing based on usage represents variable consideration. Since the variable fees relate directly to the day in which such services are provided, they generally meet the criteria for allocating variable consideration entirely to one or more, but not all, performance obligations in a contract. Accordingly, when the requisite criteria are met, variable fees are allocated to and recognized on the day the services are provided. Fees for platform and referrals services are typically billed and paid on a monthly basis. As such, the Company’s contracts with customers do not include a significant financing component. The Company did not recognize revenue from performance obligations related to prior periods for the three months ended March 31, 2020 and 2021. The Company had no material contract assets, contract liabilities, or deferred contract costs recorded as of December 31, 2020 and March 31, 2021. The Company had $8.1 million and $11.7 million of accounts receivable that are included in other assets on the condensed consolidated balance sheets related to contracts with customers as of December 31, 2020 and March 31, 2021, respectively. The Company’s allowance for bad debt was immaterial as of December 31, 2020 and March 31, 2021, and the Company’s bad debt expense was immaterial for the periods presented. The Company capitalizes incremental costs of obtaining a contract with a customer, which are certain sales commissions paid to acquire bank partners. Capitalized costs are amortized over the expected period of benefit, which we have determined, based on an analysis, to be 3 years. The Company applies the practical expedient to expense costs to obtain contracts with customers if the amortization period is one year or less. As of March 31, 2021, the Company had an immaterial amount of contract costs capitalized within other assets on the condensed consolidated balance sheets. For the three months ended March 31, 2021, the Company amortized an immaterial amount of capitalized contracts costs to sales and marketing in the condensed consolidated statements of operations and comprehensive income. For the three months ended March 31, 2020, the Company had one customer which accounted for 79% of the Company’s total revenue and two customers which accounted for 60% and 25% for the three months ended March 31, 2021. Two customers accounted for 34% and 15% of accounts receivable as of December 31, 2020 and 39% and 21% as of March 31, 2021. Servicing fees, net The Company also enters into contracts with bank partners and institutional investors to provide loan servicing for the life of Upstart-powered loans. These services commence upon origination of these loans by bank partners and include collection, processing and reconciliations of payments received, investor reporting and borrower customer support as well as distribution of funds to the holders of the loans. The Company charges the loan holder a monthly servicing fee calculated based on a predetermined percentage of the outstanding principal balance. Servicing fees also include certain ancillary fees charged on a per transaction basis for processing late payments and payments declined due to insufficient funds. Servicing fees are recognized in the period the services are provided. Loan servicing fees are not within the scope of Topic 606 and are accounted for under Topic 860, Transfers and servicing of financial assets. Servicing fees, net also include gains and losses on assets and liabilities recognized under loan servicing arrangements for loans retained by bank partners or loans sold to institutional investors. Such gains or losses are recognized based on whether the benefits of servicing are expected to more than adequately compensate the Company for carrying out its servicing obligations. Servicing fees also include changes in fair value of loan servicing assets and liabilities in the periods presented. Refer to “ Note 4. Fair Value Measurement ” for additional information on changes in fair value associated with servicing assets and liabilities. The Company recognized gains and losses related to loan servicing rights upon loan sales for the periods presented as follows: Three Months Ended March 31, 2020 2021 Net gain (loss) related to loan servicing rights $ 1,459 $ (67) The Company generally outsources borrower payment collections for loans that are more than 30 days past due or charged off to third-party collection agencies. The Company charges bank partners and institutional investors for collection agency fees related to their outstanding loan portfolio. The Company has discretion in hiring the collection agencies and determining the scope of their work. As the principal in the arrangement, the Company recognizes gross revenue from collection agency fees in the period that the services are provided. Upstart also receives certain ancillary fees inclusive of late payment fees and ACH fail fees. Revenue from collection agency fees and borrower fees are included in servicing fees, net as part of revenue from fees, net in the Company’s condensed consolidated statements of operations and comprehensive income. The total fees charged by collection agencies are also recognized in the period incurred and reported as part of customer operations expenses. The Company recognized collection agency fees and borrower fees, which are included in servicing fees, net for the periods presented as follows: Three Months Ended March 31, 2020 2021 Collection agency fees $ 800 $ 863 Borrower fees $ 517 $ 886 Interest Income and Fair Value Adjustments, Net Interest income and fair value adjustments, net is comprised of interest income, interest expense and net changes in the fair value of financial instruments, held in the Company’s normal course of business at fair value, including loans, notes receivable and residual certificates, payable to securitization note holders and residual certificate holders. The table below presents components of the interest income and fair value adjustments, net presented in the Company’s condensed consolidated statements of operations and comprehensive income: Three Months Ended March 31, 2020 2021 Interest income and fair value adjustments, net (1) : Interest income $ 9,183 $ 3,405 Interest expense (3,255) (1,030) Fair value and other adjustments, net (9,947) 2,800 Total interest income and fair value adjustments, net $ (4,019) $ 5,175 (1) Includes interest income, interest expense and fair value adjustments, net related to consolidated securitization trusts for the three months ended March 31, 2020 is as follows: Three Months Ended March 31, 2020 Interest income and fair value adjustments, net related to consolidated securitization trusts: Interest income $ 3,379 Interest expense (569) Fair value and other adjustments, net (3,000) Total interest income and fair value adjustments, net $ (190) Interest income Interest income is recognized based on the terms of the underlying agreements with borrowers for loans held on the Company’s condensed consolidated balance sheets and is earned over the life of a lioan. Interest income also includes accrued interest earned on outstanding loans but not collected. Loans that have reached a delinquency of over 120 days are classified as non-accrual status and any accrued interest recorded in relation to these loans is reversed in the respective period. As of December 31, 2020 and March 31, 2021, the Company has recorded $0.9 million and $0.7 million of accrued interest income in loans on the condensed consolidated balance sheets, respectively. Interest expense Interest expense is primarily related to interest recorded on the Company’s borrowings and the notes issued as part of the consolidated securitizations. Interest expense includes accrued interest incurred but not paid. Accrued interest expenses were immaterial as of December 31, 2020 and March 31, 2021. Fair value and other adjustments, net Fair value and other adjustments, net include changes in fair value of financial instruments, other than loan servicing assets and liabilities, common stock warrant liabilities, and convertible preferred stock warrant liabilities. These adjustments are recorded in the Company’s earnings and include both realized and unrealized changes to the value of related assets and liabilities. Refer to “ Note 4. Fair Value Measurement ” for additional information.

Securitizations and Variable In

Securitizations and Variable Interest Entities	3 Months Ended
Securitizations and Variable Interest Entities	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Securitizations and Variable Interest Entities	Securitizations and Variable Interest Entities Consolidated VIEs The Company consolidates VIEs in which the Company has a variable interest and is determined to be the primary beneficiary. This determination is based on whether the Company has a variable interest (or combination of variable interests) that provides the Company with (a) the power to direct the activities that most significantly impact the VIE’s economic performance and (b) the obligation to absorb losses or right to receive benefits that could be potentially significant to the VIE. The Company continually reassesses whether it is the primary beneficiary of a VIE throughout the entire period the Company is involved with the VIE. The Company also determines whether decision-maker or service-provider fees are variable interests. Decision-maker or service-provider fees are not considered variable interests when the arrangement does not expose the Company to risks of loss that a potential VIE was designed to pass on to its variable interest holders, the fees are commensurate, the arrangement is at market, and the Company does not have any other interests (including direct interests and certain indirect interests held through related parties) that absorb more than an insignificant amount of a VIE’s potential variability. This determination can have a significant impact on the Company’s consolidation analysis, as it could affect whether a legal entity is a VIE and whether the Company is the primary beneficiary of a VIE. When the Company’s decision-maker or service-provider fee is not a variable interest, the Company is viewed as acting as a fiduciary for the potential VIE. Warehouse Entities The Company established Upstart Loan Trust to enter into warehouse credit facilities for the purpose of purchasing Upstart-powered loans. See “ Note 7. Borrowings” for additional information. The entity is a Delaware statutory trust that is structured to be bankruptcy-remote, with third-party banks operating as trustees. Consolidated Securitizations and MOAs The Company entered into a private offering securitization transactions in April 2018 (“2018-1”). As the sponsor of the securitization transaction, the Company created legal entities for the roles of depositors, issuers, grantor trusts, and MOAs. Under the risk retention requirements in Title 17 U.S. Code of Federal Regulations Part 246, Credit Risk Retention, promulgated by Securities and Exchange Commission (“RR”), the Company is required to retain at least 5% of the economic risk in securitization transactions in which the Company is the retaining sponsor. The Company elected to satisfy the RR requirements by holding Eligible Horizontal Retained Interests (“EHRIs”) in the form of subordinated certificates within the established MOA. Concurrently with the closing of the 2018-1 securitization transaction, while maintaining its status as the primary beneficiary of the related MOA, the Company sold 80% of its interests in the MOA to an institutional investor in exchange for cash of approximately $8.0 million based on the fair value of the residual certificates held in the MOA as determined on the pricing date. As a result of the sale, the Company maintained a 20% interest in the MOA and its status as the managing member, while the investor became a non-voting limited member. As of December 31, 2020, no noncontrolling interests were recognized due to deconsolidation of the 2018-1 securitization during 2020. Upon closing of the securitization transaction, the Company determined that the servicing fees represented a variable interest in the securitization entities due to the EHRIs held by the Company’s MOA to satisfy the RR requirements. The EHRIs held by the MOA were deemed to potentially absorb more than an insignificant amount of the VIEs’ expected losses or expected returns at the inception of the securitization transaction. The Company also determined that it was the primary beneficiary of the entities and consolidated the MOA and trusts associated with the 2018-1 securitization transaction. Subsequent to the expiration of the RR requirements for 2018-1 in June 2020, the residual certificates held by the MOA was distributed based on the proportional equity held by Upstart and the investor. This distribution required the Company to reassess whether its servicing fee is a variable interest. Although the Company maintains a reduced level of variable interests in the 2018-1 securitization transaction through the EHRIs, the Company’s other interests subsequent to these distributions are no longer expected to absorb more than an insignificant amount of the VIE’s expected losses or expected returns. Therefore, the Company concluded that the fees for servicing the securitization transaction are no longer considered variable interests, and as such the powers the Company possesses through the servicing arrangement is no longer considered in the primary beneficiary determination. As a result, the Company concluded it was no longer the primary beneficiary of the 2018-1 securitization transaction. The Company deconsolidated the legal entities associated with the 2018-1 securitization as of June 30, 2020. The Company recorded an immaterial net gain on the deconsolidation of the entities. The Company maintained its role as servicer of these securitization transactions. The Company sponsored three additional securitization transactions in August 2018 (“2018-2”), February 2019 (“2019-1”) and August 2019 (“2019-2”), respectively. As the retaining sponsor of these transactions, the Company was subject to the RR requirements and satisfied them through Eligible Vertical Interests (“EVIs”) in the form of a combination of securitization notes and residual certificates through the established MOAs. The Company concluded that it has a variable interest and is the primary beneficiary of the MOAs associated with these securitization transactions. As a result, the Company consolidated these MOAs as of December 31, 2020 and 2019. The Company determined that it is not the primary beneficiary of the trusts which hold the loans associated with these securitization transactions, primarily because the Company’s servicing fees are not considered variable interests, and that the transfer of loans as collateral into these securitization transactions met the definition of a sale under Topic 860, Transferring and Servicing. As such, the Company derecognized these loans from the condensed consolidated balance sheets upon the closing of these securitization transactions. Refer to the Unconsolidated Securitizations section below for more information. Other Consolidated VIEs Upstart Loan Trust 2, a Delaware statutory trust, holds personal loans facilitated through the Upstart platform that do not meet the criteria for inclusion in the warehouse credit facilities, or that were the result of the Company’s repurchases of loans for breaches of representations and warranties made to institutional investors, as described above. The following tables present a summary of financial assets and liabilities from the Company’s involvement with consolidated VIEs: Assets Liabilities Net Assets December 31, 2020 Warehouse Entities $ 71,530 $ 35,109 $ 36,421 Majority-owned Affiliates 17,219 7,187 10,032 Other Consolidated VIEs 16,243 — 16,243 Total Consolidated VIEs $ 104,992 $ 42,296 $ 62,696 Assets Liabilities Net Assets March 31, 2021 Warehouse Entities $ 47,329 $ 16,394 $ 30,935 Majority-owned Affiliates 14,678 5,105 9,573 Other Consolidated VIEs 24,716 — 24,716 Total Consolidated VIEs $ 86,723 $ 21,499 $ 65,224 The Company’s continued involvement in all of its securitizations in which it is the sponsor includes loan servicing rights and obligations for which it receives servicing fees over the life of the underlying loans. The Company monitors its status as the primary beneficiary and in case of reconsideration events, updates the analysis accordingly. Unconsolidated VIEs The Company’s transactions with unconsolidated VIEs include securitizations of unsecured personal whole loans and sales of whole loans to VIEs. The Company has various forms of involvement with VIEs, including servicing of loans and holding senior or residual interests in the VIEs. The Company’s transactions with unconsolidated VIEs include securitizations of unsecured personal whole loans and sales of whole loans to VIEs. The Company has various forms of involvement with VIEs, including servicing of loans and holding senior or residual interests in the VIEs. Unconsolidated Securitizations As of March 31, 2021, the Company’s unconsolidated VIEs include entities established as the issuers and grantor trusts for the 2017-1, 2017-2, 2018-1, 2018-2, 2019-1, and 2019-2 securitization transactions (the “Unconsolidated Securitizations”). The Company’s continued involvement in the unconsolidated VIEs is in the form of its role as the sponsor and the servicer of these transactions. For each of the unconsolidated securitizations, the Company determined that it is not the primary beneficiary. In cases where the VIEs are not consolidated and the transfer of the loans from the Company to the securitization trust meets sale accounting criteria, the Company recognizes a gain or loss on sales of loans. The net proceeds of the sale represent the fair value of any assets obtained or liabilities incurred as part of the transaction. The assets are transferred into a trust such that the assets are legally isolated from the creditors of the Company and are not available to satisfy obligations of the Company. These assets can only be used to settle obligations of the underlying securitization trusts. Upstart Network Trust Upstart Network Trust (“UNT”), also a Delaware statutory trust, was established in 2014 to facilitate Upstart’s fractional loan program. The Company is the servicer of UNT’s loan assets and previously concluded that the servicing fee represents a variable interest and that the Company is the primary beneficiary of UNT. The program was formally discontinued in 2019 and as a result of a reduction in the Company’s investment in UNT, the Company concluded that it was no longer the primary beneficiary and therefore deconsolidated UNT during 2019. The fair value of the Company’s investment in UNT is included in notes receivable and residual certificates in the condensed consolidated balance sheets as of December 31, 2020 and March 31, 2021. The Company’s continued involvement in UNT includes loan servicing rights and obligations for which it receives servicing fees over the life of the underlying loans The following tables summarize the aggregate carrying value of assets and liabilities of unconsolidated VIEs in which the Company holds a variable interest but is not the primary beneficiary: Assets Liabilities Net Assets Maximum Exposure to Losses December 31, 2020 Securitizations $ 484,604 $ 390,252 $ 94,352 $ 24,434 Upstart Network Trust 39,754 39,754 — 1,707 Total Unconsolidated VIEs $ 524,358 $ 430,006 $ 94,352 $ 26,141 Assets Liabilities Net Assets Maximum Exposure to Losses March 31, 2021 Securitizations $ 407,667 $ 315,994 $ 91,673 $ 21,893 Upstart Network Trust 31,427 31,427 — 1,355 Total Unconsolidated VIEs $ 439,094 $ 347,421 $ 91,673 $ 23,248 The carrying value of assets that relate to variable interests in unconsolidated VIEs consists of $18.9 million and $16.0 million which are included in notes receivable and residual certificates on the condensed consolidated balance sheets as of December 31, 2020 and March 31, 2021, respectively. The Company also had $7.2 million of cash deposits made to reserve accounts for related securitizations, included in other assets on the condensed consolidated balance sheets as of December 31, 2020 and March 31, 2021. The Company’s maximum exposure to loss from its involvement with unconsolidated VIEs represents the estimated loss that would be incurred under severe, hypothetical circumstances, for which the Company believes the possibility is remote, such as where the value of securitization notes and senior and residual certificates the Company holds as part of the RR requirement declines to zero. Retained Interest in Unconsolidated VIEs The investors and the securitization trusts have no direct recourse to the Company’s assets, and holders of the securities issued by the securitization trusts can look only to the assets of the securitization trusts that issued their securities for payment. The beneficial interests held by the Company and the Company’s MOAs are subject principally to the credit and prepayment risk stemming from the underlying unsecured personal whole loans. Off-Balance Sheet Loans Off-balance sheet loans relate to securitization transactions for which the Company has some form of continuing involvement, including as servicer. For a loan related to securitization transactions where servicing is the only form of continuing involvement, the Company would only experience a loss if it were required to repurchase such a loan due to a breach in representations and warranties associated with its loan sale or servicing contracts. Additionally, in the unlikely event principal payments on the loans backing a securitization are insufficient to pay senior note holders, any amounts the Company contributed to the securitization reserve accounts may be depleted. In December 2019, February 2020, October 2020, and February 2021, the Company co-sponsored securitization transactions (“2019-3”, “2020-1”, “2020-3”, “2021-1”, respectively) with an investment bank. The

Fair Value Measurement

Fair Value Measurement	3 Months Ended
Fair Value Measurement	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement The following table presents assets and liabilities measured at fair value and categorized as Level 3 in the fair value hierarchy: December 31, March 31, 2020 2021 Assets Loans $ 78,460 $ 57,189 Notes receivable and residual certificates 19,074 16,033 Loan servicing assets 6,831 8,734 Total assets $ 104,365 $ 81,956 Liabilities Loan servicing liabilities $ 8,254 $ 10,853 Trailing fee liabilities 1,276 1,775 Total liabilities $ 9,530 $ 12,628 Financial instruments are categorized in the fair value hierarchy based on the significance of unobservable factors in the overall fair value measurement. Since the Company’s loans, notes receivable and residual certificates, other assets, loan servicing assets and liabilities, and trailing fee liabilities do not trade in an active market with readily observable prices, the Company uses significant unobservable inputs to measure the fair value of these assets and liabilities. There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy during the periods presented. Loans Loans included in the Company’s condensed consolidated balance sheets are classified as either held-for-sale or held-for-investment. The Company reclassified loans held by the warehouse entities from held-for-investment to held-for-sale as of January 1, 2020, due to the Company’s intent to sell the loans prior to maturity and increasing evidence of their marketability. Other loans held on the Company’s condensed consolidated balance sheets retained their classification as held-for-investment. These loans include loans which do not satisfy the warehouse requirements and loans held in the consolidated securitizations. The following table presents the fair value of classes of loans held by the Company: December 31, March 31, 2020 2021 Loans held-for-sale $ 60,232 $ 28,794 Loans held-for-investment 18,228 28,395 Total $ 78,460 $ 57,189 Valuation Methodology Loans held-for-sale and held-for-investment are measured at estimated fair value using a discounted cash flow model. The fair valuation methodology considers projected prepayments and historical defaults, losses and recoveries to project future losses and net cash flows on loans. Net cash flows are discounted using an estimate of market rates of return. The fair value of these loans also includes accrued interest, which was immaterial as of December 31, 2020 and March 31, 2021. For the three months ended March 31, 2020 and 2021, the Company elected the measurement alternative under Topic 810, Consolidation, and maximizes the use of observable inputs to estimate the fair value of the financial assets and liabilities of consolidated securitization entities. Under the measurement alternative, the Company measures the financial assets, which consist of held-for-investment and held-for-sale loans in the condensed consolidated balance sheets, and financial liabilities, which consist of securitization notes and residual certificates issued to institutional investors, included in payable to securitization note holders and residual certificate holders in the condensed consolidated balance sheets, using the more observable of the fair value of the financial assets and liabilities. The Company determined the fair value of the amounts payable to securitization note holders and residual certificate holders is more observable than that of the loans. The securitization notes and residual certificates are measured at fair value, and the loans are measured based on the sum of the fair value of the securitization notes and residual certificates, with changes in fair value included in the condensed consolidated statements of operations and comprehensive income. Significant Inputs and Assumptions The following table presents quantitative information about the significant unobservable inputs used for the Company’s Level 3 fair value measurements for loans held-for-investment and held-for-sale: December 31, 2020 March 31, 2021 Minimum Maximum Weighted-Average (2) Minimum Maximum Weighted-Average (2) Discount rate 6.80 % 16.99 % 7.44 % 3.52 % 16.60 % 6.74 % Credit risk rate (1) 0.36 % 52.31 % 19.82 % 0.21 % 52.31 % 23.09 % Prepayment rate (1) 11.64 % 78.36 % 31.03 % 12.69 % 78.53 % 33.68 % (1) Expressed as a percentage of the original principal balance of the loans (2) Unobservable inputs were weighted by relative fair value Discount rates –The discount rates are rates of return used to discount future expected cash flows to arrive at a present value, which represents the fair value. The discount rates used for the projected net cash flows are the Company’s estimates of the rates of return that market participants would require when investing in these financial instruments with cash flows dependent on credit quality of the related loan. A risk premium component is implicitly included in the discount rates to reflect the amount of compensation market participants require due to the uncertainty inherent in the instruments’ cash flows resulting from risks such as credit and liquidity. Credit risk rates –The credit risk rates are an estimate of the net cumulative principal payments that will not be repaid over the entire life of a financial instrument. The credit risk rates are expressed as a percentage of the original principal amount of the instrument. The estimated net cumulative loss represents the sum of the net losses estimated to occur each month of the life of the instrument, net of the average recovery expected to be received. Prepayment rates –Prepayment rates are an estimate of the cumulative principal prepayments that will occur over the entire life of a loan as a percentage of the original principal amount of the loan. The assumption regarding cumulative prepayments impact the projected balances and expected terms of the loans. The above inputs are similarly used in estimating fair value of related financial instruments. Refer to the Assets and Liabilities related to Securitization Transactions section below for more information. Significant Recurring Level 3 Fair Value Input Sensitivity The below table presents the sensitivity of the loans held-for-sale and held-for-investment to adverse changes in key assumptions used in the valuation model as of December 31, 2020 and March 31, 2021, respectively. The estimated fair value of these loans is not sensitive to adverse changes in expected prepayment rates as such changes would not result in a significant impact on the fair value in either periods. December 31, March 31, 2020 2021 Fair value of loans $ 78,460 $ 57,189 Discount rates 100 basis point increase (979) (714) 200 basis point increase (1,939) (1,415) Expected credit loss rates on underlying loans 10% adverse change (1,303) (1,087) 20% adverse change (2,611) (2,126) Rollforward of Level 3 Fair Values The following tables include a rollforward of the loans classified within Level 3 of the fair value hierarchy: Loans Held-for- Loans Held-for-Investment Loans Held-for- Total Fair value at December 31, 2019 $ — $ 141,555 $ 90,750 $ 232,305 Reclassification of loans from HFI to HFS 125,297 (125,297) — — Purchases of loans 97,924 2,755 — 100,679 Sale of loans (94,949) — — (94,949) Purchase of loans for immediate resale to investors 848,540 — — 848,540 Immediate resale to investors (848,540) — — (848,540) Repayments received (6,446) (1,311) (15,273) (23,030) Changes in fair value recorded in earnings (5,281) (1,019) (8,143) (14,443) Other changes (34) 75 (2) 39 Fair value at March 31, 2020 $ 116,511 $ 16,758 $ 67,332 $ 200,601 Loans Held-for- Loans Held-for-Investment Loans Held-for- Total Fair value at December 31, 2020 $ 60,232 $ 18,228 $ — $ 78,460 Reclassification of loans from HFI to HFS (26) 26 — — Purchases of loans 18,240 12,947 — 31,187 Sale of loans (46,469) — — (46,469) Purchase of loans for immediate resale to investors 1,294,634 — — 1,294,634 Immediate resale to investors (1,294,634) — — (1,294,634) Repayments received (3,310) (2,329) — (5,639) Changes in fair value recorded in earnings 357 (558) — (201) Other changes (230) 81 — (149) Fair value at March 31, 2021 $ 28,794 $ 28,395 $ — $ 57,189 Assets related to Securitization Transactions As of December 31, 2020 and March 31, 2021, the Company held notes receivable and residual certificates with an aggregate fair value of $19.1 million and $16.0 million, respectively. The balances consist of securitization notes and residual certificates corresponding to the 5% economic risk retention the Company is required to maintain as the retaining sponsor of the unconsolidated securitizations. Valuation Methodology The discounted cash flow methodology is used to estimate the fair value of notes receivable and residual certificates, using the same projected net cash flows as their related loans. This model uses inputs that are inherently judgmental and reflect the Company’s best estimates of the assumptions a market participant would use to calculate fair value. Significant Inputs and Assumptions The following table presents quantitative information about the significant unobservable inputs used for the Company’s Level 3 fair value measurements of assets related to securitization transactions: December 31, 2020 March 31, 2021 Minimum Maximum Weighted-Average (2) Minimum Maximum Weighted-Average (2) Notes receivable and residual certificates Discount rate 3.01 % 14.00 % 5.84 % 3.01 % 14.00 % 5.83 % Credit risk rate (1) 0.04 % 50.69 % 17.12 % 0.04 % 50.69 % 17.40 % Prepayment rate (1) 15.60 % 36.88 % 27.63 % 15.60 % 36.88 % 27.67 % (1) Expressed as a percentage of the original principal balance of the loans underlying the financial instruments (2) Unobservable inputs were weighted by relative fair value Significant Recurring Level 3 Fair Value Input Sensitivity The securities issued in the securitization transactions are senior or subordinated based on the waterfall criteria of loan payments to each security class, with the residual interest (the “residual certificates”) issued being the first to absorb credit losses in accordance with the waterfall criteria. Accordingly, the residual certificates are the most sensitive to adverse changes in credit risk rates. Depending on the specific securitization, a hypothetical increase in the credit risk rate of 10% to 20% would result in significant decreases in the fair value of the residual certificates. On average, a hypothetical increase in the credit risk rate of 20% would result in a 17% decrease in the fair value of the residual certificates. The remaining classes of securities, with the exception of those in 2018-2, are all overcollateralized such that changes in credit risk rates are not expected to have significant impacts on their fair values. The fair value of the securities is also sensitive to adverse changes in discount rates, which represent estimates of the rates of return that institutional investors would require when investing in financial instruments with similar risk and return characteristics. On average, a hypothetical 100 basis point increase in discount rates results in a decrease in fair value of the securities (including securitization notes and residual certificates) of 1.23% and 1.05% as of December 31, 2020 and March 31, 2021, respectively. On average, a hypothetical 200 basis point increase in discount rates results in a decrease in fair value of the securities (including securitization notes and residual certificates) of 2.36% and 2.08% as of December 31, 2020 and March 31, 2021, respectively. The fair value of securitization notes and residual certificates are not sensitive to adverse changes in expected prepayment rates as such changes would not result in a significant impact on the fair value as of December 31, 2020 and March 31, 2021. Rollforward of Level 3 Fair Values The following tables include a rollforward of the notes receivable and residual certificates related to securitization transactions classified by the Company within Level 3 of the fair value hierarchy: Notes Receivable and Residual Certificates Fair value at December 31, 2019 $ 34,116 Purchases and issuances of securitization notes and residual certificates 4 Repayments and settlements (4,028) Changes in fair value recorded in earnings (3,196) Fair value at March 31, 2020 $ 26,896 Notes Receivable and Residual Certificates Fair value at December 31, 2020 $ 19,074 Repayments and settlements (3,119) Changes in fair value recorded in earnings 78 Fair value at March 31, 2021 $ 16,033 Loan Servicing Assets and Liabilities Valuation Methodology Loan servicing assets and liabilities are measured at estimated fair value using a discounted cash flow model. The cash flows in the valuation model represent the difference between the contractual servicing fees charged to institutional investors and an estimated market servicing fee. Since contractual servicing fees are generally based on the monthly unpaid principal balance of the underlying loans, the expected cash flows in the model incorporate estimates of net losses and prepayments. Significant Inputs and Assumptions The following table presents quantitative information about the significant unobservable inputs used for the Company’s Level 3 fair value measurements for loan servicing assets and liabilities: December 31, 2020 March 31, 2021 Minimum Maximum Weighted-Average (2) Minimum Maximum Weighted-Average (2) Discount rate 15.00 % 35.00 % 22.69 % 15.00 % 35.00 % 22.88 % Credit risk rate (1) 0.03 % 52.78 % 17.19 % 0.03 % 52.78 % 17.73 % Market-servicing rate (3)(4) 0.75 % 0.75 % 0.75 % 0.75 % 0.75 % 0.75 % Prepayment rate (1) 9.07 % 89.01 % 31.62 % 8.61 % 88.79 % 32.43 % (1) Expressed as a percentage of the original principal balance of the loans underlying the servicing arrangement (2) Unobservable inputs were weighted by relative fair value (3) Excludes ancillary fees that would be passed on to a third-party servicer (4) Expressed as a percentage of the outstanding principal balance of the loan Discount rates –The discount rates are the Company’s estimate of the rates of return that market participants in servicing rights would require when investing in similar servicing rights. Discount rates for servicing rights on existing loans are adjusted to reflect the time value of money and a risk premium intended to reflect the amount of compensation market participants would require due to the uncertainty associated with these instruments’ cash flows. Credit risk rate s–The credit risk rates are the Company’s estimate of the net cumulative principal payments that will not be repaid over the entire life of a loan expressed as a percentage of the original principal amount of the loan. The assumption regarding net cumulative losses impact the projected balances and expected terms of the loans, which are used to project future servicing revenues. Market-servicing rates –Market-servicing rate is an estimated measure of adequate compensation for a market participant, if one was required. The rate is expressed as a fixed percentage of outstanding principal balance on a per annum basis. The estimate considers the profit that would be demanded in the marketplace to service the portfolio of outstanding loans subject to the Company’s servicing agreements. Prepayment rates –Prepayment rates are the Company’s estimate of the cumulative principal prepayments that will occur over the entire life of a loan as a percentage of the original principal amount of the loan. The assumption regarding cumulative prepayments impact the projected balances and expected terms of the loans, which are used to project future servicing revenues. Significant Recurring Level 3 Fair Value Input Sensitivity The table below presents the fair value sensitivity of loan servicing assets and liabilities to adverse changes in key assumptions. The fair value of loan servicing assets and liabilities is not sensitive to adverse changes in discount rates as such changes would not result in a significant impact on the fair value as of December 31, 2020 and March 31, 2021, respectively. December 31, March 31, 2020 2021 Fair value of loan servicing assets $ 6,831 $ 8,734 Expected market-servicing rates 10% market-servicing rates increase (19,013) (20,061) 20% market-servicing rates increase (38,027) (40,122) Expected prepayment rates 10% adverse change (2,061) (4,646) 20% adverse change (4,212) (2,273) December 31, March 31, 2020 2021 Fair value of loan servicing liabilities $ 8,254 $ 10,853 Expected market-servicing rates 10% market-servicing rates increase 22,974 24,928 20% market-servicing rates increase 45,948 49,857 Expected prepayment rates 10% adverse change 2,491 5,773 20% adverse change 5,089 2,825 Rollforward of Level 3 Fair Values The following table presents a rollforward of the loan servicing assets and liabilities classified by the Company within Level 3 of the fair value hierarchy: Loan Servicing Assets Loan Servicing Liabilities Fair value at December 31, 2019 $ 4,725 $ 5,140 Sale of loans 2,705 1,246 Changes in fair value recorded in earnings (808) (480) Fair value at March 31, 2020 $ 6,622 $ 5,906 Loan Servicing Assets Loan Servicing Liabilities Fair value at December 31, 2020 $ 6,831 $ 8,254 Sale of loans 3,452 3,519 Changes in fair value recorded in earnings (1,549) (920) Fair value at March 31, 2021 $ 8,734 $ 10,853 Trailing Fee Liabilities The Company pays certain bank partners monthly trailing fees based on the amount and timing of principal and interest payments made by borrowers of the underlying loans. Significant inputs used for estimating the fair value of trailing fee liabilities included discount rates of 3.52% to 16.60% and credit risk rates of 0.21% to 52.31%. The fair value sensitivity of trailing fee liabilities to adverse changes in key assumptions would not result in a material impact on the Company’s financial position. Rollforward of Level 3 Fair Values The following tables include a rollforward of trailing fee liabilities classified by the Company within Level 3 of the fair value hierarchy: Trailing Fee Liabilities Fair value at December 31, 2019 $ 504 Issuances 312 Repayments and settlements (54) Fair value at March 31, 2020 $ 762 Trailing Fee Liabilities Fair value at December 31, 2020 $ 1,276 Issuances 669 Repayments and settlements (170) Fair value at March 31, 2021 $ 1,775

Loans at Fair Value

Loans at Fair Value	3 Months Ended
Loans at Fair Value	Mar. 31, 2021
Receivables [Abstract]
Loans at Fair Value	Loans at Fair Value The following table presents the aggregate fair value and aggregate principal outstanding of all loans and loans that were 90 days or more past due included in the condensed consolidated balance sheets: Loans Loans > 90 Days Past Due December 31, 2020 March 31, 2021 December 31, 2020 March 31, 2021 Outstanding principal balance $ 97,497 $ 76,573 $ 2,018 $ 3,592 Net fair value and accrued interest adjustments (19,037) (19,384) (2,002) (3,577) Fair value $ 78,460 $ 57,189 $ 16 $ 15

Balance Sheet Components

Balance Sheet Components	3 Months Ended
Balance Sheet Components	Mar. 31, 2021
Other Assets [Abstract]
Balance Sheet Components	Balance Sheet Components Other Assets Other assets consisted of the following: December 31, March 31 2020 2021 Servicing fees and other receivables $ 11,656 $ 18,134 Deposits 7,947 8,165 Prepaid expenses 6,009 14,203 Loan servicing assets (at fair value) 6,831 8,734 Other assets 7,603 2,701 Total other assets $ 40,046 $ 51,937 Servicing fees and other receivables represent amounts recognized as revenue but not yet collected in relation to servicing and other agreements with institutional investors and bank partners. Property, Equipment, and Software, Net Property, equipment, and software, net consisted of the following: December 31, March 31 2020 2021 Internally developed software $ 7,906 $ 8,362 Computer equipment 1,285 1,711 Furniture and fixtures 1,770 1,770 Leasehold improvements 2,763 2,763 Total property, equipment, and software 13,724 14,606 Accumulated depreciation and amortization (3,692) (4,508) Total property, equipment, and software, net $ 10,032 $ 10,098 For the three months ended March 31, 2020 and 2021, depreciation and amortization expense on property, equipment, and software was immaterial. Capitalized internally developed software balances, net of accumulated amortization, were $6.0 million as of both December 31, 2020 and March 31, 2021 Accrued Expenses and Other Liabilities Accrued expenses and other liabilities consisted of the following: December 31, March 31 2020 2021 Accrued expenses $ 10,974 $ 19,791 Accrued payroll 13,834 6,282 Loan servicing liabilities (at fair value) 8,254 10,853 Trailing fee liability (at fair value) 1,276 1,775 Other liabilities 1,331 4,168 Total accrued expenses and other liabilities $ 35,669 $ 42,869

Borrowings

Borrowings	3 Months Ended
Borrowings	Mar. 31, 2021
Debt Disclosure [Abstract]
Borrowings	Borrowings The following table presents the aggregate principal outstanding of all loans mentioned in this note that are included in the condensed consolidated balance sheets: Borrowings December 31, 2020 March 31, 2021 Term loans $ 15,000 $ 15,000 Revolving credit facility 5,500 5,500 Warehouse credit facilities 34,994 16,323 Risk retention funding loans 7,187 5,105 Total payments due 62,681 41,928 Unamortized debt discount (55) (37) Total borrowings $ 62,626 $ 41,891 Term Loans In October 2018, the Company and UNI entered into a mezzanine loan and security agreement to obtain a second term loan of up to $15.0 million (the “Mezzanine Loan”). The Mezzanine Loan bears interest at the greater of prime rate plus 5.25% or 10.00% per annum, payable monthly. The principal balance is due upon maturity on October 1, 2021. The term loans are secured by all assets of the Company, excluding assets of consolidated securitizations and cash and restricted cash relating to other borrowing arrangements. Revolving Credit Facility In connection with the LSA with the same lender above, as amended in September 2018, the Company and UNI also obtained a revolving credit facility of up to $5.5 million (the “UNI Credit Facility”). The UNI Credit Facility had an original termination and maturity date of June 1, 2020. In 2020, the parties agreed to extend the maturity date of the UNI Credit Facility to June 1, 2021 when the outstanding principal and any accrued and unpaid interest are due and payable in full. The UNI Credit Facility bears floating interest at the greater of prime rate plus 1.00% or 4.25% annum, payable monthly, subject to a monthly minimum interest requirement prior to maturity. The UNI Credit Facility is secured by all assets of the Company, excluding assets of consolidated securitizations and cash and restricted cash relating to other borrowing arrangements. The UNI Credit Facility contains certain financial covenants. As of December 31, 2020 and March 31, 2021, the Company was in compliance with all applicable covenants under the revolving credit and security agreement. As of December 31, 2020 and March 31, 2021, outstanding borrowings under the UNI Credit Facility was $5.5 million. Warehouse Credit Facility In November 2015, the Company’s consolidated VIE, Upstart Loan Trust (“ULT”), entered into a revolving credit and security agreement with a third-party lender (the “ULT Warehouse Credit Facility”). The credit and security agreement for the ULT Warehouse Credit Facility was amended and restated in its entirety in May 2020. Under the revolving credit and security agreement, as amended from time to time, ULT may borrow up to $100.0 million (subject to a borrowing base capacity) until the earlier of May 15, 2021 or the occurrence of an accelerated amortization event. An accelerated amortization event includes failure to satisfy certain loan performance metrics or the occurrence of an event of default. The proceeds may only be used to purchase unsecured personal loans from Upstart’s platform and to pay fees and expenses related to the credit facility. The ULT Warehouse Credit Facility matures on the earlier of May 15, 2022 or acceleration of the facility following an event of default, upon which date 100% of the outstanding principal amount, together with any accrued and unpaid interest, becomes due and payable. The entire amount of the outstanding principal and interest may be prepaid at any time without penalty. The ULT Warehouse Credit Facility bears a floating interest rate of LIBOR plus a spread ranging from 3.35% to 4.00% per annum, due and payable monthly in arrears. The Company is subject to additional interest payments under a minimum utilization requirement of $35 million. The maximum advance rate under the ULT Warehouse Credit Facility on outstanding principal of loans held by ULT was 80% as of December 31, 2020 and March 31, 2021. The ULT Warehouse Credit Facility contains certain financial covenants. As of March 31, 2021 and 2020, ULT was in material compliance with all applicable covenants under the ULT Warehouse Credit Facility. The creditors of ULT have no recourse to the general credit of the Company, except for certain limited obligations of ULT to its creditors that are guaranteed by the Company. The Company does not guarantee the credit performance of the loans owned by ULT, and the loans and other assets owned by ULT are not available to settle the claims of creditors of the Company. The following table includes the aggregate balances held by ULT that were pledged as collateral for the ULT Warehouse Credit Facility and included in loans at fair value and restricted cash in the condensed consolidated balance sheets, respectively: ULT Warehouse Credit Facility December 31, 2020 March 31, 2021 Outstanding borrowings $ 34,994 $ 16,323 Aggregate outstanding principal of loans pledged as collateral 59,709 28,854 Aggregate fair value of loans purchased and held by ULT 60,231 28,795 Restricted cash pledged as collateral 11,270 18,487 Risk Retention Funding Loans In October 2018, Upstart RR Funding 2018-2, LLC (the “2018-2 RR entity”), a consolidated VIE of UNI, entered into a loan and security agreement (the “2018-2 RR Financing Agreement”) to finance the Company’s risk retention balance in the Upstart Securitization Trust 2018-2. Under this agreement, the balance borrowed by the 2018-2 RR entity has an interest rate of 4.00% per annum and is repaid using cash proceeds received by the 2018-2 RR entity as part of monthly cash distributions from the 2018-2 securitization on securitization notes and residual certificates. As of December 31, 2020 and March 31, 2021, the outstanding principal balance under the 2018-2 RR Financing Agreement was immaterial. In September 2019, Upstart RR Funding 2019-2, LLC (the “2019-2 RR entity”), a consolidated VIE of UNI, entered into a loan and security agreement (the “2019-2 RR Financing Agreement”) to finance the Company’s risk retention balance in the Upstart Securitization Trust 2019-2. Under this agreement, the balance borrowed by the 2019-2 RR entity has an annual interest rate of 4.33% and is repaid using cash proceeds received by the 2019-2 RR entity as part of monthly cash distributions from the 2019-2 securitization on securitization notes and residual certificates. As of December 31, 2020 and March 31, 2021, the outstanding principal balance under the 2019-2 RR Financing Agreement was $6.6 million and $5.1 million, respectively. The borrowings are solely the obligations of the 2018-2 RR entity and 2019-2 RR entity, respectively, and the Company is not obligated thereon. The securities and other assets owned by each RR entity are not available to settle the claims of creditors of the Company. Assets pledged as collateral for the risk retention funding loans include $12.6 million and $10.8 million of securities held for risk retention for the 2018-2 and 2019-2 securitization transactions, included in notes receivables and residual certificates on the condensed consolidated balance sheets as of December 31, 2020 and March 31, 2021, respectively. The following table summarizes the aggregate amount of maturities of all borrowings as of March 31, 2021: March 31, 2021 Remainder of 2021 $ 20,500 2022 16,357 2023 5,071 2024 — 2025 — Total $ 41,928

Common Stock and Common Stock W

Common Stock and Common Stock Warrants	3 Months Ended
Common Stock and Common Stock Warrants	Mar. 31, 2021
Equity [Abstract]
Common Stock and Common Stock Warrants	Common Stock and Common Stock Warrants Common Stock In December 2020, the Company's amended and restated certificate of incorporation became effective, which authorized the issuance of 700,000,000 shares of common stock with a par value of $0.0001 per share. The Company had reserved shares of common stock for issuance, on an as-converted basis, as follows: December 31, March 31, 2020 2021 Options issued and outstanding 19,600,223 19,590,771 RSUs outstanding — 827,192 Shares available for future issuance under 2020 plan 2,537,181 10,389,402 Shares available for issuance under ESPP — 2,113,140 Warrants to purchase common stock 75,000 — Total 22,212,404 32,920,505 Common Stock Warrants In October 2018, the Company issued stock warrants to purchase 75,000 shares of common stock, with an exercise price of $2.16 per share. The estimated grant date fair value of the common stock warrants was recognized as debt issuance costs in the period granted. The common stock warrant has a contractual term of ten years and expire in October 2028. On December 1, 2020, the common stock warrant agreement was amended to include a repurchase option in the event of an IPO. Upon the completion of an IPO, or a qualified acquisition of the Company, the common stock warrant holders have the option to require the Company to repurchase the warrant in its entirety for a purchase price of $1.5 million. The repurchase option terminates on the earlier of (i) 30 days after the closing of a qualified

Equity Incentive Plans

Equity Incentive Plans	3 Months Ended
Equity Incentive Plans	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Equity Incentive Plans	Equity Incentive Plans Equity Incentive Plans In 2012, the Company adopted the Equity Incentive Plan (“2012 Equity Incentive Plan”) authorizing the granting of incentive stock options (“ISOs”) and non-statutory stock options (“NSOs”) to eligible participants. Under the 2012 Equity Incentive Plan, the exercise price of an ISO and NSO shall not be less than 100% of the estimated fair value of the shares on the date of grant, as determined by the Board of Directors. The exercise price of an ISO granted to a 10% stockholder shall not be less than 110% of the estimated fair value of the shares on the date of grant, as determined by the Board of Directors. Options generally vest over four years and are exercisable for up to 10 years after the date of grant if the employee provides service to the Company for at least three years. In October 2020, our Board of Directors adopted, and in November 2020 our Board of Directors amended and our stockholders approved, our 2020 Equity Incentive Plan which was effective on December 14, 2020. The Company terminated the 2012 Equity Incentive Plan immediately prior to effectiveness of the 2020 Equity Incentive Plan with respect to the grant of future awards. However, our 2012 Equity Incentive Plan continues to govern the terms and conditions of the outstanding awards granted under our 2012 Equity Incentive Plan. The 2020 Equity Incentive Plan authorizes granting of ISOs, NSOs, stock appreciation rights, restricted stock, restricted stock units, or RSUs, and performance awards. As of March 31, 2021, the Company is authorized to issue up to 10,389,402 shares of common stock under the 2020 Equity Incentive Plan. In addition, the 2020 Equity Incentive Plan also includes any shares subject to awards granted under our 2012 Equity Incentive Plan that, on or after December 15, 2020, expire or otherwise terminate without having been exercised or issued in full, are tendered to or withheld by us for payment of an exercise price or for satisfying tax withholding obligations, or are forfeited to or repurchased by us due to failure to vest. The maximum number of shares that may be added to the 2020 Equity Incentive Plan pursuant to outstanding awards under the 2012 Equity Incentive Plan is 15,000,000 shares. The number of shares available for issuance under our 2020 Equity Incentive Plan also includes an annual increase on the first day of each fiscal year beginning with the 2021 in an amount equal to the least of 15,000,000 shares or 5% of the outstanding shares of our common stock on the last day of our immediately preceding fiscal year. Stock Options The following table summarized stock option activity for three months ended March 31, 2021: Number of Options Weighted-Average Exercise Price Per Share Weighted-Average Remaining Contractual Life (years) Aggregate Balances at December 31, 2020 19,600,223 $ 4.27 6.8 $ 715,084 Options granted 606,830 Options exercised (521,511) Options cancelled and forfeited (94,771) Balances at March 31, 2021 19,590,771 $ 7.42 6.6 $ 2,379,126 Options exercisable – March 31, 2021 11,309,977 $ 1.65 4.9 $ 1,438,789 Options vested and expected to vest – March 31, 2021 19,168,127 $ 6.95 6.5 $ 2,336,779 The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the fair value of the Company’s stock as of March 31, 2021. The aggregate intrinsic value of options exercised for the three months ended March 31, 2020 and 2021, was $0.8 million and $65.7 million, respectively. The weighted-average grant date fair value of options granted during the three months ended March 31, 2020 and 2021, was $5.23 and $61.67 per share, respectively. The total fair value of options vested for the three months ended March 31, 2020 and 2021, was $1.0 million and $3.6 million, respectively. As of March 31, 2021, total unrecognized stock-based compensation expense related to unvested stock options was $77.3 million, which is expected to be recognized over a remaining weighted-average period of 2.4 years. Restricted Stock Units During the three months ended March 31, 2021, the Company began granting RSUs to employees and nonemployees. RSUs vest upon satisfaction of a service-based condition, which is generally satisfied over four years. The following table summarized RSU activity for three months ended March 31, 2021: Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested at December 31, 2020 — RSUs granted 835,307 $ 101.56 RSUs vested (342) $ 81.56 RSUs cancelled and forfeited (7,773) $ 124.14 Unvested at March 31, 2021 827,192 As of March 31, 2021, total unrecognized stock-based compensation expense related to outstanding unvested RSUs was $82.1 million, which is expected to be recognized over a remaining weighted-average period of 3.5 years. 2020 Employee Stock Purchase Plan In October 2020, our Board of Directors adopted, and in November 2020 our Board of Directors amended and our stockholders approved, our ESPP which was effective on December 14, 2020. Our ESPP provides for consecutive six-month offering periods. The offering periods are scheduled to start on the first trading day on or after February 15 and August 15 of each year, except the first offering period commenced on December 16, 2020 and will end on the first trading day on or before August 15, 2021. The second offering period will commence on the last trading day on or after August 15, 2021. The ESPP permits participants to purchase shares in the amount of 85% of the lower of the fair market value of our shares of common stock on the first trading day of the offering period or on the exercise date. As of March 31, 2021, the maximum number of shares of common stock that can be issued under the employee stock purchase plan was 2,113,140 shares, in addition to any automatic annual evergreen increase. As of March 31, 2021, no shares of common stock have been purchased under the ESPP. As of March 31, 2021, total unrecognized stock-based compensation expense related to ESPP was $3.1 million, which is expected to be recognized over a remaining weighted-average period of 0.4 years. Fair Value of Awards Granted In determining the fair value of the stock-based awards, the Company uses the Black-Scholes option-pricing model and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment. Fair Value of Common Stock - Prior to the completion of the IPO, the fair value of the shares of common stock was determined by the Company’s Board of Directors as there was no public market for the Company’s common stock. After the completion of the IPO, the fair value of the Company’s common stock is determined by the closing price, on the date of grant, of its common stock, which is traded on the Nasdaq Global Select Market. Expected Term - The expected term represents the period that the Company’s stock options are expected to be outstanding. The Company determined the expected term for employee stock options based on historical terminations and exercise behavior, which factors in an extended post-termination exercise provision for vested awards for certain employees that provide more than three years of service to the Company. The Company uses the contractual term for all nonemployee awards. Volatility - Because the Company does not have an active trading market for its common stock for a sufficient period of time, the expected volatility is estimated based on the average volatility for comparable publicly-traded companies, over a period equal to the expected term of the stock option grants. Risk-free Interest Rate - The risk-free interest rate assumption is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of the option. Dividends - The Company has never paid dividends on its common stock and does not anticipate paying dividends on common stock. Therefore, the Company uses an expected dividend yield of zero. The following assumptions were used to estimate the fair value of options granted: Three Months Ended March 31, 2020 2021 Expected term (in years) 5.4 – 10.0 5.3 – 6.9 Expected volatility 53.23% – 55.35% 63.12% – 65.01% Risk-free interest rate 1.34% – 1.50% 0.62% – 1.14% Dividend yield — % — % The following assumptions were used to estimate the fair value of the Company’s ESPP for the initial offering period: Three Months Ended March 31, 2021 Expected term (in years) 0.6 Expected volatility 61.65% Risk-free interest rate 0.09% Dividend yield — % Stock-Based Compensation The Company recorded stock-based compensation in the following expense categories in its condensed consolidated statements of operations and comprehensive income for employees and nonemployees: Three Months Ended March 31, 2020 2021 Sales and marketing $ 284 $ 753 Customer operations 199 752 Engineering and product development 926 4,307 General, administrative, and other 556 2,810 Total $ 1,965 $ 8,622 Stock-based compensation expense by award type was as follows: Three Months Ended March 31, 2020 2021 Stock options $ 1,965 $ 5,120 RSUs — 1,445 ESPP — 2,057 Total $ 1,965 $ 8,622

Leases

Leases	3 Months Ended
Leases	Mar. 31, 2021
Leases [Abstract]
Leases	Leases The Company’s operating leases are primarily for its corporate headquarters in San Mateo, California and Columbus, Ohio. Both operating leases include early termination options, and one of the leases includes renewal options for two successive five-year periods. The exercise of these options was not recognized as part of the ROU assets and lease liabilities, as the Company did not conclude, at the commencement date of the leases, that the exercise of renewal options or termination options was reasonably certain. In connection with one of the leases, a letter of credit was issued on behalf of the Company for the benefit of the landlord in the amount of $2.0 million. The letter of credit is secured by a certificate of deposit which is included in restricted cash on the condensed consolidated balance sheets. As of March 31, 2021, future minimum non-cancelable lease payments are as follows: Operating Leases Remainder of 2021 $ 3,483 2022 5,221 2023 5,516 2024 2,567 2025 1,579 Thereafter 2,417 Total undiscounted lease payments 20,783 Less: Present value adjustment (2,162) Operating lease liabilities $ 18,621 As of March 31, 2021, the Company does not have any operating leases which are yet to commence. As of March 31, 2021 the Company did not have any material finance leases. The Company’s operating lease expense consists of rent and variable lease payments. Variable lease payments such as common area maintenance and parking fees, were included in operating expenses. Rent expense for the Company’s short-term leases was immaterial for the three months ended March 31, 2020 and 2021. Operating lease expense was as follows: Three Months Ended March 31, 2020 2021 Rent expense $ 1,269 $ 1,528 Variable lease payments $ 355 $ 299 Supplemental cash flow and noncash information related to the Company’s operating leases was as follows: Three Months Ended March 31, 2020 2021 Cash flows from operating activities Cash paid for amounts included in the measurement of lease liabilities $ 1,011 $ 1,057 Supplemental cash flow and noncash information related to the Company’s operating leases was as follows: March 31, 2021 Weighted average remaining lease term (in years) 4.37 Weighted average discount rate 5.09%

Commitment and Contingencies

Commitment and Contingencies	3 Months Ended
Commitment and Contingencies	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Loan Purchase Obligation Under the Company’s loan agreements with certain bank partners, the banks retain ownership of the loans facilitated through Upstart’s platform for three days or longer (the “holding period”) after origination, as required under the respective agreements. The Company has committed to purchase the loans at the unpaid principal balance, plus accrued interest, at the conclusion of the required holding period. As of December 31, 2020 and March 31, 2021, the total loan purchase commitment included outstanding principal balance of $39.3 million and $82.4 million, respectively. Repurchase and Indemnification Contingency Under the terms of the loan purchase and loan servicing agreements between the Company and institutional investors, as well as in agreements with investors in securitizations where the Company is not the sponsor, the Company may, in certain circumstances, become obligated to repurchase loans from such investors. Generally, these circumstances include the occurrence of verifiable identity theft, the failure of sold loans to meet the terms of certain loan-level representations and warranties that speak as of the time of origination or sale, the failure to comply with other contractual terms with the investors, or a violation of the applicable federal, state, or local lending laws. The maximum potential amount of future payments associated under this obligation is the outstanding balances of the loans sold to the investors, which at December 31, 2020 and March 31, 2021, is $5,180.7 million and $6,224.0 million, respectively. The Company recognizes a liability for the repurchase obligation based on historical experience when the loans are issued. The liability is subsequently remeasured when a related loss is probable and can be reasonably estimated. Actual payments made relating to the Company’s repurchase and indemnification obligations were immaterial historically. The Company has recorded contingent liabilities as of December 31, 2020 and March 31, 2021 of immaterial amounts to cover estimated future obligations related to these contractual terms. These amounts are included in accrued expenses and other liabilities on the Company’s condensed consolidated balance sheets. Legal From time to time the Company is subject to, and it is presently involved in, litigation and other legal proceedings. Accounting for contingencies requires the Company to use judgment related to both the likelihood of a loss and the estimate of the amount or range of loss. The Company records a loss contingency when it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. As of December 31, 2020 and March 31, 2021, no loss contingency has been recorded in connection with legal proceedings arising in the ordinary course of business. Contingencies Accounting for contingencies requires the Company to use judgment related to both the likelihood of a loss and the estimate of the amount or range of loss. The Company records a loss contingency when it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. The Company discloses material contingencies when it believes a loss is not probable but reasonably possible. Although the Company cannot reasonably determine the outcome of any litigation or tax matters, it does not believe there are currently any such actions that, if resolved unfavorably, would have a material impact on its condensed consolidated financial statements. Indemnifications In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to vendors, directors, officers and other parties with respect to certain matters. In addition, the Company has entered into indemnification agreements with directors and certain officers and employees that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. No demands have been made upon the Company to provide indemnification under such agreements, and thus, there are no claims that the Company is aware of that could have a material effect on the Company’s condensed consolidated financial statements.

Income Taxes

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income TaxesThe Company’s effective tax rates for the three months ended March 31, 2020 and 2021, were 0% and 1.96%. The change in the tax rate for the three months ended March 31, 2021 was due to an increase in state tax expense after utilizing taxable losses in the various jurisdictions. The effective tax rate differs from the U.S. statutory tax rate primarily due to the valuation allowance on the Company’s deferred tax assets as it is more likely than not that some or all of these deferred tax assets will not be realized.

Related Party Transactions

Related Party Transactions	3 Months Ended
Related Party Transactions	Mar. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionsSince the Company’s inception, it has engaged in various transactions with its executive officers and directors, holders of more than 10% of its voting securities, and their affiliates.The related party investor and its affiliates also participated in securitization transactions co-sponsored and serviced by the Company in the three months ended March 31, 2020 by contributing loans and purchasing securitization notes or residual certificates.

Net Income Per Share Attributab

Net Income Per Share Attributable to Upstart Holdings, Inc. Common Stockholders	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Income Per Share Attributable to Upstart Holdings, Inc. Common Stockholders	Net Income Per Share Attributable to Upstart Holdings, Inc. Common Stockholders Basic net income per common share attributable to Upstart Holdings, Inc.’s common stockholders is based on the weighted-average common shares outstanding during the relevant period. Diluted net income per common share attributable to Upstart Holdings, Inc.’s common stockholders is based on the weighted-average common shares outstanding during the relevant period adjusted for the dilutive effect of share-based awards. Three Months Ended March 31, 2020 2021 Numerator: Net income attributable to Upstart Holdings, Inc. common stockholders $ 1,480 $ 10,102 Less: noncumulative dividends to preferred stockholders (1,480) — Net income attributable to common stockholders, basic and diluted $ — $ 10,102 Denominator: Weighted-average common shares outstanding used to calculate net income per share attributable to Upstart Holdings, Inc. common stockholders, basic 14,625,267 73,629,122 Weighted-average effect of dilutive securities — 17,820,449 Weighted-average common shares outstanding used to calculate net income per share attributable to Upstart Holdings, Inc. common stockholders, diluted 14,625,267 91,449,571 Net income per share attributable to Upstart Holdings, Inc. common stockholders, basic $ — $ 0.14 Net income per share attributable to Upstart Holdings, Inc. common stockholders, diluted $ — $ 0.11 The following securities were excluded from the computation of diluted net income per share attributable to Upstart Holdings, Inc. common stockholders for the periods presented, because including them would have been anti-dilutive for the three months ended March 31, 2020. Three Months Ended March 31, 2020 2021 Convertible preferred stock 47,349,577 — Options to purchase common stock 18,087,958 617,424 Unvested RSUs — 737,682 Warrants to purchase convertible preferred stock 600,208 — Warrants to purchase common stock 319,669 — Total 66,357,412 1,355,106

Subsequent Events

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has evaluated the impact of events that have occurred subsequent to March 31, 2021, through May 14, 2021, the date which the condensed consolidated financial statements were available to be issued. Based on the evaluation, the Company has determined no subsequent events were required to be recognized or disclosed except the matters described below. Prodigy Software, Inc. Acquisition On April 8, 2021, the Company completed its acquisition of Prodigy Software, Inc. (“Prodigy”). Prodigy provides an e-commerce platform for car dealerships which enables both online and in-store vehicle discovery, credit application, and checkout. The Company has acquired Prodigy with the intention of integrating its lending business with Prodigy’s auto-sales platform and expanding its auto lending footprint. The total consideration the Company paid for Prodigy was approximately $98.8 million and consisted of cash and shares of the Company’s common stock. On the closing date, the Company paid $18.0 million in cash and issued 650,767 shares of common stock. Due to the proximity of the acquisition date to the Company’s filing of its quarterly report on Form 10-Q for the quarter ended March 31, 2021, the initial accounting for the Prodigy business combination is underway, and therefore the Company has not yet disclosed certain information required by ASC 805, Business Combinations, including the provisional amounts recognized as of the acquisition date for each major class of assets acquired, liabilities assumed, and goodwill. Follow-on Offering

Description of Business and S_2

Description of Business and Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Consolidation	The accompanying unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements included in our Annual Report on Form 10-K and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to state fairly the Company’s financial position, results of operations, comprehensive income and cash flows for the periods presented, but are not necessarily indicative of the results of operations to be anticipated of any future annual or interim periods. Certain information and disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to rules and regulations of the Securities and Exchange Commission. Accordingly, the information included in this Quarterly Report on Form 10-Q should be read in conjunction with the consolidated financial statements and accompanying notes included in our Annual Report on Form 10-K for the year ended December 31, 2020.
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements included in our Annual Report on Form 10-K and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to state fairly the Company’s financial position, results of operations, comprehensive income and cash flows for the periods presented, but are not necessarily indicative of the results of operations to be anticipated of any future annual or interim periods. Certain information and disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to rules and regulations of the Securities and Exchange Commission. Accordingly, the information included in this Quarterly Report on Form 10-Q should be read in conjunction with the consolidated financial statements and accompanying notes included in our Annual Report on Form 10-K for the year ended December 31, 2020.
Use of Estimates	Use of Estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires that management 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 condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods.
Stock-Based Compensation	Stock-Based Compensation The Company issues stock options and restricted stock units (“RSUs”) to employees and nonemployees, including directors and third-party service providers, and employee stock purchase rights granted under the Company’s employee stock purchase plan (“ESPP”). Stock options and employee stock purchase rights granted under the ESPP are initially measured at fair value at the date of grant using the Black-Scholes option-pricing model. RSUs are measured at the fair market value of our common stock at the grant date. Stock-based
Recently Adopted And Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements The Company adopted the following accounting standards during the three months ended March 31, 2021: In August 2018, the FASB issued ASU 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract , which requires a customer in a hosting arrangement that is a service contract to follow the internal-use software guidance in Topic 350-40 to determine which implementation costs to capitalize as assets or expense as incurred. The standard is effective January 1, 2021 for emerging growth companies that have adopted the private company relief. The amendments in this ASU can be applied either retrospectively or prospectively to all implementation costs after the date of adoption. The guidance became effective on January 1, 2021 and the Company adopted the standard on a prospective basis. The adoption of the standard did not have a material impact on the Company’s financial statements or related disclosures. In August 2020, the FASB issued ASU No. 2020-06, Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , which simplifies accounting for convertible instruments by removing major separation models required under current U.S. GAAP. The standard removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and also simplifies the diluted earnings per share calculation in certain areas The amendments in this update are effective for public business entities for fiscal years beginning after December 15, 2021, and interim periods within those fiscal years. The amendment is to be adopted through either a fully retrospective or modified retrospective method of transition. Early adoption is permitted. The Company early adopted ASU 2020-06 on January 1, 2021 with no material impact on the Company’s financial statements or related disclosures. Recently Issued Accounting Pronouncements In June 2016, the FASB amended guidance related to impairment of financial instruments as part of ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which will be effective January 1, 2023 for emerging growth companies that have adopted the private company relief. The guidance replaces the incurred loss impairment methodology with an expected credit loss model for which a company recognizes an allowance based on the estimate of expected credit loss. The Company accounts for its loans at fair value through net income, which is outside the scope of Topic 326. For available for sale debt securities, the guidance will require recognition of expected credit losses by recognizing an allowance for credit losses when the fair value of the security is below amortized cost and the recognition of this allowance is limited to the difference between the security’s amortized cost basis and fair value. The Company is evaluating the impact this ASU will have on its condensed consolidated balance sheets, condensed consolidated statements of operations and comprehensive income, condensed consolidated statements of cash flows and related disclosures. The Company plans to adopt Topic 326 effective as of January 1, 2023. In March 2020 the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting followed by and ASU 2021-01, Reference Rate Reform, Scop e issued in January 2021. ASU 2020-04 and ASU 2021-01 provide temporary optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions that reference the London Interbank Offered Rate or another reference rate expected to be discontinued because of reference rate reform, if certain criteria are met. The guidance in ASU 2020-04 and ASU 2021-01 was effective upon issuance and, once adopted, may be applied prospectively to contract modifications and hedging relationships through December 31, 2022. The Company is currently evaluating the impact of the adoption of ASU 2020-04 and ASU 2021-01 on its condensed consolidated financial statements and related disclosures.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
Revenue (Tables)	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue By Type of Service	The Company disaggregates revenue from fees by type of service for the periods presented as follows: Three Months Ended March 31, 2020 2021 Revenue from fees, net: Platform and referral fees, net $ 60,230 $ 106,953 Servicing fees, net 7,783 9,217 Total revenue from fees, net $ 68,013 $ 116,170
Gain (Loss) on Loan Servicing Rights	The Company recognized gains and losses related to loan servicing rights upon loan sales for the periods presented as follows: Three Months Ended March 31, 2020 2021 Net gain (loss) related to loan servicing rights $ 1,459 $ (67)
Schedule of Collection Agency And Borrower Fees	The Company recognized collection agency fees and borrower fees, which are included in servicing fees, net for the periods presented as follows: Three Months Ended March 31, 2020 2021 Collection agency fees $ 800 $ 863 Borrower fees $ 517 $ 886
Components of The Interest Income and Fair Value Adjustments, Net	The table below presents components of the interest income and fair value adjustments, net presented in the Company’s condensed consolidated statements of operations and comprehensive income: Three Months Ended March 31, 2020 2021 Interest income and fair value adjustments, net (1) : Interest income $ 9,183 $ 3,405 Interest expense (3,255) (1,030) Fair value and other adjustments, net (9,947) 2,800 Total interest income and fair value adjustments, net $ (4,019) $ 5,175 (1) Includes interest income, interest expense and fair value adjustments, net related to consolidated securitization trusts for the three months ended March 31, 2020 is as follows: Three Months Ended March 31, 2020 Interest income and fair value adjustments, net related to consolidated securitization trusts: Interest income $ 3,379 Interest expense (569) Fair value and other adjustments, net (3,000) Total interest income and fair value adjustments, net $ (190)

Securitizations and Variable _2

Securitizations and Variable Interest Entities (Tables)	3 Months Ended
Securitizations and Variable Interest Entities (Tables)	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Financial Assets And Liabilities From Variable Interest Entities	The following tables present a summary of financial assets and liabilities from the Company’s involvement with consolidated VIEs: Assets Liabilities Net Assets December 31, 2020 Warehouse Entities $ 71,530 $ 35,109 $ 36,421 Majority-owned Affiliates 17,219 7,187 10,032 Other Consolidated VIEs 16,243 — 16,243 Total Consolidated VIEs $ 104,992 $ 42,296 $ 62,696 Assets Liabilities Net Assets March 31, 2021 Warehouse Entities $ 47,329 $ 16,394 $ 30,935 Majority-owned Affiliates 14,678 5,105 9,573 Other Consolidated VIEs 24,716 — 24,716 Total Consolidated VIEs $ 86,723 $ 21,499 $ 65,224 The following tables summarize the aggregate carrying value of assets and liabilities of unconsolidated VIEs in which the Company holds a variable interest but is not the primary beneficiary: Assets Liabilities Net Assets Maximum Exposure to Losses December 31, 2020 Securitizations $ 484,604 $ 390,252 $ 94,352 $ 24,434 Upstart Network Trust 39,754 39,754 — 1,707 Total Unconsolidated VIEs $ 524,358 $ 430,006 $ 94,352 $ 26,141 Assets Liabilities Net Assets Maximum Exposure to Losses March 31, 2021 Securitizations $ 407,667 $ 315,994 $ 91,673 $ 21,893 Upstart Network Trust 31,427 31,427 — 1,355 Total Unconsolidated VIEs $ 439,094 $ 347,421 $ 91,673 $ 23,248

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	3 Months Ended
Fair Value Measurement (Tables)	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Assets And Liabilities Measure At Fair Value	The following table presents assets and liabilities measured at fair value and categorized as Level 3 in the fair value hierarchy: December 31, March 31, 2020 2021 Assets Loans $ 78,460 $ 57,189 Notes receivable and residual certificates 19,074 16,033 Loan servicing assets 6,831 8,734 Total assets $ 104,365 $ 81,956 Liabilities Loan servicing liabilities $ 8,254 $ 10,853 Trailing fee liabilities 1,276 1,775 Total liabilities $ 9,530 $ 12,628
Fair Value Of Classes of Loans Held	The following table presents the fair value of classes of loans held by the Company: December 31, March 31, 2020 2021 Loans held-for-sale $ 60,232 $ 28,794 Loans held-for-investment 18,228 28,395 Total $ 78,460 $ 57,189
Significant Unobservable Inputs	The following table presents quantitative information about the significant unobservable inputs used for the Company’s Level 3 fair value measurements for loans held-for-investment and held-for-sale: December 31, 2020 March 31, 2021 Minimum Maximum Weighted-Average (2) Minimum Maximum Weighted-Average (2) Discount rate 6.80 % 16.99 % 7.44 % 3.52 % 16.60 % 6.74 % Credit risk rate (1) 0.36 % 52.31 % 19.82 % 0.21 % 52.31 % 23.09 % Prepayment rate (1) 11.64 % 78.36 % 31.03 % 12.69 % 78.53 % 33.68 % (1) Expressed as a percentage of the original principal balance of the loans (2) Unobservable inputs were weighted by relative fair value The following table presents quantitative information about the significant unobservable inputs used for the Company’s Level 3 fair value measurements of assets related to securitization transactions: December 31, 2020 March 31, 2021 Minimum Maximum Weighted-Average (2) Minimum Maximum Weighted-Average (2) Notes receivable and residual certificates Discount rate 3.01 % 14.00 % 5.84 % 3.01 % 14.00 % 5.83 % Credit risk rate (1) 0.04 % 50.69 % 17.12 % 0.04 % 50.69 % 17.40 % Prepayment rate (1) 15.60 % 36.88 % 27.63 % 15.60 % 36.88 % 27.67 % (1) Expressed as a percentage of the original principal balance of the loans underlying the financial instruments (2) Unobservable inputs were weighted by relative fair value
Sensitivity Analysis of Fair Value	The below table presents the sensitivity of the loans held-for-sale and held-for-investment to adverse changes in key assumptions used in the valuation model as of December 31, 2020 and March 31, 2021, respectively. The estimated fair value of these loans is not sensitive to adverse changes in expected prepayment rates as such changes would not result in a significant impact on the fair value in either periods. December 31, March 31, 2020 2021 Fair value of loans $ 78,460 $ 57,189 Discount rates 100 basis point increase (979) (714) 200 basis point increase (1,939) (1,415) Expected credit loss rates on underlying loans 10% adverse change (1,303) (1,087) 20% adverse change (2,611) (2,126)
Rollforward Of Level 3 Assets	The following tables include a rollforward of the loans classified within Level 3 of the fair value hierarchy: Loans Held-for- Loans Held-for-Investment Loans Held-for- Total Fair value at December 31, 2019 $ — $ 141,555 $ 90,750 $ 232,305 Reclassification of loans from HFI to HFS 125,297 (125,297) — — Purchases of loans 97,924 2,755 — 100,679 Sale of loans (94,949) — — (94,949) Purchase of loans for immediate resale to investors 848,540 — — 848,540 Immediate resale to investors (848,540) — — (848,540) Repayments received (6,446) (1,311) (15,273) (23,030) Changes in fair value recorded in earnings (5,281) (1,019) (8,143) (14,443) Other changes (34) 75 (2) 39 Fair value at March 31, 2020 $ 116,511 $ 16,758 $ 67,332 $ 200,601 Loans Held-for- Loans Held-for-Investment Loans Held-for- Total Fair value at December 31, 2020 $ 60,232 $ 18,228 $ — $ 78,460 Reclassification of loans from HFI to HFS (26) 26 — — Purchases of loans 18,240 12,947 — 31,187 Sale of loans (46,469) — — (46,469) Purchase of loans for immediate resale to investors 1,294,634 — — 1,294,634 Immediate resale to investors (1,294,634) — — (1,294,634) Repayments received (3,310) (2,329) — (5,639) Changes in fair value recorded in earnings 357 (558) — (201) Other changes (230) 81 — (149) Fair value at March 31, 2021 $ 28,794 $ 28,395 $ — $ 57,189 The following tables include a rollforward of the notes receivable and residual certificates related to securitization transactions classified by the Company within Level 3 of the fair value hierarchy: Notes Receivable and Residual Certificates Fair value at December 31, 2019 $ 34,116 Purchases and issuances of securitization notes and residual certificates 4 Repayments and settlements (4,028) Changes in fair value recorded in earnings (3,196) Fair value at March 31, 2020 $ 26,896 Notes Receivable and Residual Certificates Fair value at December 31, 2020 $ 19,074 Repayments and settlements (3,119) Changes in fair value recorded in earnings 78 Fair value at March 31, 2021 $ 16,033
Level 3 Fair Value Assumptions for Loan Servicing Assets and Liabilities	The following table presents quantitative information about the significant unobservable inputs used for the Company’s Level 3 fair value measurements for loan servicing assets and liabilities: December 31, 2020 March 31, 2021 Minimum Maximum Weighted-Average (2) Minimum Maximum Weighted-Average (2) Discount rate 15.00 % 35.00 % 22.69 % 15.00 % 35.00 % 22.88 % Credit risk rate (1) 0.03 % 52.78 % 17.19 % 0.03 % 52.78 % 17.73 % Market-servicing rate (3)(4) 0.75 % 0.75 % 0.75 % 0.75 % 0.75 % 0.75 % Prepayment rate (1) 9.07 % 89.01 % 31.62 % 8.61 % 88.79 % 32.43 % (1) Expressed as a percentage of the original principal balance of the loans underlying the servicing arrangement (2) Unobservable inputs were weighted by relative fair value (3) Excludes ancillary fees that would be passed on to a third-party servicer (4) Expressed as a percentage of the outstanding principal balance of the loan
Fair Value Sensitivity of Loan Servicing Assets And Liabilities to Adverse Changes in Key Assumptions	The table below presents the fair value sensitivity of loan servicing assets and liabilities to adverse changes in key assumptions. The fair value of loan servicing assets and liabilities is not sensitive to adverse changes in discount rates as such changes would not result in a significant impact on the fair value as of December 31, 2020 and March 31, 2021, respectively. December 31, March 31, 2020 2021 Fair value of loan servicing assets $ 6,831 $ 8,734 Expected market-servicing rates 10% market-servicing rates increase (19,013) (20,061) 20% market-servicing rates increase (38,027) (40,122) Expected prepayment rates 10% adverse change (2,061) (4,646) 20% adverse change (4,212) (2,273) December 31, March 31, 2020 2021 Fair value of loan servicing liabilities $ 8,254 $ 10,853 Expected market-servicing rates 10% market-servicing rates increase 22,974 24,928 20% market-servicing rates increase 45,948 49,857 Expected prepayment rates 10% adverse change 2,491 5,773 20% adverse change 5,089 2,825
Servicing Liabilities at Fair Value Rollforward	The following table presents a rollforward of the loan servicing assets and liabilities classified by the Company within Level 3 of the fair value hierarchy: Loan Servicing Assets Loan Servicing Liabilities Fair value at December 31, 2019 $ 4,725 $ 5,140 Sale of loans 2,705 1,246 Changes in fair value recorded in earnings (808) (480) Fair value at March 31, 2020 $ 6,622 $ 5,906 Loan Servicing Assets Loan Servicing Liabilities Fair value at December 31, 2020 $ 6,831 $ 8,254 Sale of loans 3,452 3,519 Changes in fair value recorded in earnings (1,549) (920) Fair value at March 31, 2021 $ 8,734 $ 10,853
Servicing Assets at Fair Value Rollforward	The following table presents a rollforward of the loan servicing assets and liabilities classified by the Company within Level 3 of the fair value hierarchy: Loan Servicing Assets Loan Servicing Liabilities Fair value at December 31, 2019 $ 4,725 $ 5,140 Sale of loans 2,705 1,246 Changes in fair value recorded in earnings (808) (480) Fair value at March 31, 2020 $ 6,622 $ 5,906 Loan Servicing Assets Loan Servicing Liabilities Fair value at December 31, 2020 $ 6,831 $ 8,254 Sale of loans 3,452 3,519 Changes in fair value recorded in earnings (1,549) (920) Fair value at March 31, 2021 $ 8,734 $ 10,853
Rollforward of Level 3 Liabilities	The following tables include a rollforward of trailing fee liabilities classified by the Company within Level 3 of the fair value hierarchy: Trailing Fee Liabilities Fair value at December 31, 2019 $ 504 Issuances 312 Repayments and settlements (54) Fair value at March 31, 2020 $ 762 Trailing Fee Liabilities Fair value at December 31, 2020 $ 1,276 Issuances 669 Repayments and settlements (170) Fair value at March 31, 2021 $ 1,775

Loans at Fair Value (Tables)

Loans at Fair Value (Tables)	3 Months Ended
Loans at Fair Value (Tables)	Mar. 31, 2021
Receivables [Abstract]
Aggregate Fair Value and Principal Outstanding of All Loans and Loans 90 days or More Past Due	The following table presents the aggregate fair value and aggregate principal outstanding of all loans and loans that were 90 days or more past due included in the condensed consolidated balance sheets: Loans Loans > 90 Days Past Due December 31, 2020 March 31, 2021 December 31, 2020 March 31, 2021 Outstanding principal balance $ 97,497 $ 76,573 $ 2,018 $ 3,592 Net fair value and accrued interest adjustments (19,037) (19,384) (2,002) (3,577) Fair value $ 78,460 $ 57,189 $ 16 $ 15

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
Balance Sheet Components (Tables)	Mar. 31, 2021
Other Assets [Abstract]
Schedule of Other Assets	Other assets consisted of the following: December 31, March 31 2020 2021 Servicing fees and other receivables $ 11,656 $ 18,134 Deposits 7,947 8,165 Prepaid expenses 6,009 14,203 Loan servicing assets (at fair value) 6,831 8,734 Other assets 7,603 2,701 Total other assets $ 40,046 $ 51,937
Schedule of Property, Equipment, and Software	Property, equipment, and software, net consisted of the following: December 31, March 31 2020 2021 Internally developed software $ 7,906 $ 8,362 Computer equipment 1,285 1,711 Furniture and fixtures 1,770 1,770 Leasehold improvements 2,763 2,763 Total property, equipment, and software 13,724 14,606 Accumulated depreciation and amortization (3,692) (4,508) Total property, equipment, and software, net $ 10,032 $ 10,098
Accrued Expenses and Other Liabilities	Accrued expenses and other liabilities consisted of the following: December 31, March 31 2020 2021 Accrued expenses $ 10,974 $ 19,791 Accrued payroll 13,834 6,282 Loan servicing liabilities (at fair value) 8,254 10,853 Trailing fee liability (at fair value) 1,276 1,775 Other liabilities 1,331 4,168 Total accrued expenses and other liabilities $ 35,669 $ 42,869

Borrowings (Tables)

Borrowings (Tables)	3 Months Ended
Borrowings (Tables)	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Aggregate Principal Outstanding Of All Loans	The following table presents the aggregate principal outstanding of all loans mentioned in this note that are included in the condensed consolidated balance sheets: Borrowings December 31, 2020 March 31, 2021 Term loans $ 15,000 $ 15,000 Revolving credit facility 5,500 5,500 Warehouse credit facilities 34,994 16,323 Risk retention funding loans 7,187 5,105 Total payments due 62,681 41,928 Unamortized debt discount (55) (37) Total borrowings $ 62,626 $ 41,891
Schedule of Assets Pledge as Collateral	The following table includes the aggregate balances held by ULT that were pledged as collateral for the ULT Warehouse Credit Facility and included in loans at fair value and restricted cash in the condensed consolidated balance sheets, respectively: ULT Warehouse Credit Facility December 31, 2020 March 31, 2021 Outstanding borrowings $ 34,994 $ 16,323 Aggregate outstanding principal of loans pledged as collateral 59,709 28,854 Aggregate fair value of loans purchased and held by ULT 60,231 28,795 Restricted cash pledged as collateral 11,270 18,487
Schedule of Maturities of All Borrowings	The following table summarizes the aggregate amount of maturities of all borrowings as of March 31, 2021: March 31, 2021 Remainder of 2021 $ 20,500 2022 16,357 2023 5,071 2024 — 2025 — Total $ 41,928

Common Stock and Common Stock_2

Common Stock and Common Stock Warrants (Tables)	3 Months Ended
Common Stock and Common Stock Warrants (Tables)	Mar. 31, 2021
Equity [Abstract]
Schedule of shares and warrants reserved for issuance	The Company had reserved shares of common stock for issuance, on an as-converted basis, as follows: December 31, March 31, 2020 2021 Options issued and outstanding 19,600,223 19,590,771 RSUs outstanding — 827,192 Shares available for future issuance under 2020 plan 2,537,181 10,389,402 Shares available for issuance under ESPP — 2,113,140 Warrants to purchase common stock 75,000 — Total 22,212,404 32,920,505

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	3 Months Ended
Equity Incentive Plans (Tables)	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Summarized Stock Option Activity	The following table summarized stock option activity for three months ended March 31, 2021: Number of Options Weighted-Average Exercise Price Per Share Weighted-Average Remaining Contractual Life (years) Aggregate Balances at December 31, 2020 19,600,223 $ 4.27 6.8 $ 715,084 Options granted 606,830 Options exercised (521,511) Options cancelled and forfeited (94,771) Balances at March 31, 2021 19,590,771 $ 7.42 6.6 $ 2,379,126 Options exercisable – March 31, 2021 11,309,977 $ 1.65 4.9 $ 1,438,789 Options vested and expected to vest – March 31, 2021 19,168,127 $ 6.95 6.5 $ 2,336,779
Summaries Restricted Stock Unit Activity	The following table summarized RSU activity for three months ended March 31, 2021: Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested at December 31, 2020 — RSUs granted 835,307 $ 101.56 RSUs vested (342) $ 81.56 RSUs cancelled and forfeited (7,773) $ 124.14 Unvested at March 31, 2021 827,192
Stock Options Fair Value Assumptions	The following assumptions were used to estimate the fair value of options granted: Three Months Ended March 31, 2020 2021 Expected term (in years) 5.4 – 10.0 5.3 – 6.9 Expected volatility 53.23% – 55.35% 63.12% – 65.01% Risk-free interest rate 1.34% – 1.50% 0.62% – 1.14% Dividend yield — % — %
Employee Stock Purchase Plan Fair Value Assumptions	The following assumptions were used to estimate the fair value of the Company’s ESPP for the initial offering period: Three Months Ended March 31, 2021 Expected term (in years) 0.6 Expected volatility 61.65% Risk-free interest rate 0.09% Dividend yield — %
Stock-Based Compensation Expense	The Company recorded stock-based compensation in the following expense categories in its condensed consolidated statements of operations and comprehensive income for employees and nonemployees: Three Months Ended March 31, 2020 2021 Sales and marketing $ 284 $ 753 Customer operations 199 752 Engineering and product development 926 4,307 General, administrative, and other 556 2,810 Total $ 1,965 $ 8,622 Stock-based compensation expense by award type was as follows: Three Months Ended March 31, 2020 2021 Stock options $ 1,965 $ 5,120 RSUs — 1,445 ESPP — 2,057 Total $ 1,965 $ 8,622

Leases (Tables)

Leases (Tables)	3 Months Ended
Leases (Tables)	Mar. 31, 2021
Leases [Abstract]
Future Minimum Non-Cancelable Lease Payments	As of March 31, 2021, future minimum non-cancelable lease payments are as follows: Operating Leases Remainder of 2021 $ 3,483 2022 5,221 2023 5,516 2024 2,567 2025 1,579 Thereafter 2,417 Total undiscounted lease payments 20,783 Less: Present value adjustment (2,162) Operating lease liabilities $ 18,621
Operating Lease Expense And Supplemental Cash and Non-Cash Information	Operating lease expense was as follows: Three Months Ended March 31, 2020 2021 Rent expense $ 1,269 $ 1,528 Variable lease payments $ 355 $ 299 Supplemental cash flow and noncash information related to the Company’s operating leases was as follows: Three Months Ended March 31, 2020 2021 Cash flows from operating activities Cash paid for amounts included in the measurement of lease liabilities $ 1,011 $ 1,057 Supplemental cash flow and noncash information related to the Company’s operating leases was as follows: March 31, 2021 Weighted average remaining lease term (in years) 4.37 Weighted average discount rate 5.09%

Net Income Per Share Attribut_2

Net Income Per Share Attributable to Upstart Holdings, Inc. Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Net Income Per Share Attributable to Common Stockholders	Basic net income per common share attributable to Upstart Holdings, Inc.’s common stockholders is based on the weighted-average common shares outstanding during the relevant period. Diluted net income per common share attributable to Upstart Holdings, Inc.’s common stockholders is based on the weighted-average common shares outstanding during the relevant period adjusted for the dilutive effect of share-based awards. Three Months Ended March 31, 2020 2021 Numerator: Net income attributable to Upstart Holdings, Inc. common stockholders $ 1,480 $ 10,102 Less: noncumulative dividends to preferred stockholders (1,480) — Net income attributable to common stockholders, basic and diluted $ — $ 10,102 Denominator: Weighted-average common shares outstanding used to calculate net income per share attributable to Upstart Holdings, Inc. common stockholders, basic 14,625,267 73,629,122 Weighted-average effect of dilutive securities — 17,820,449 Weighted-average common shares outstanding used to calculate net income per share attributable to Upstart Holdings, Inc. common stockholders, diluted 14,625,267 91,449,571 Net income per share attributable to Upstart Holdings, Inc. common stockholders, basic $ — $ 0.14 Net income per share attributable to Upstart Holdings, Inc. common stockholders, diluted $ — $ 0.11
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following securities were excluded from the computation of diluted net income per share attributable to Upstart Holdings, Inc. common stockholders for the periods presented, because including them would have been anti-dilutive for the three months ended March 31, 2020. Three Months Ended March 31, 2020 2021 Convertible preferred stock 47,349,577 — Options to purchase common stock 18,087,958 617,424 Unvested RSUs — 737,682 Warrants to purchase convertible preferred stock 600,208 — Warrants to purchase common stock 319,669 — Total 66,357,412 1,355,106

Description of Business and S_3

Description of Business and Significant Accounting Policies (Details) - USD ($)	1 Months Ended		3 Months Ended
	Mar. 31, 2021	Apr. 30, 2020	Mar. 31, 2021	Mar. 31, 2020
Short-term Debt [Line Items]
Period of payment deferral		6 months
Repayments of debt			$ 26,584,000	$ 78,011,000
Paycheck Protection Program Loan, CARES Act
Short-term Debt [Line Items]
Debt, face amount		$ 5,300,000
Stated interest rate		1.00%
Repayments of debt	$ 5,300,000

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from fees, net	$ 116,170	$ 68,013
Platform and referral fees, net
Disaggregation of Revenue [Line Items]
Revenue from fees, net	106,953	60,230
Servicing fees, net
Disaggregation of Revenue [Line Items]
Revenue from fees, net	$ 9,217	$ 7,783

Revenue - Narrative (Details)

Revenue - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
Revenue - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Trailing fee liability (at fair value)	$ 1,775		$ 1,276
Servicing fees and other receivables	18,134		11,656
Accrued interest income	$ 700		$ 900
Customers \| Total Revenue
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)		79.00%
Customer One \| Customers \| Total Revenue
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	60.00%
Customer One \| Customers \| Accounts Receivable
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	39.00%		34.00%
Customer Two \| Customers \| Total Revenue
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	25.00%
Customer Two \| Customers \| Accounts Receivable
Disaggregation of Revenue [Line Items]
Concentration risk (in percent)	21.00%		15.00%
Platform and referral fees, net
Disaggregation of Revenue [Line Items]
Loan premium and loan trailing fees recognized	$ 3,600	$ 2,400
Trailing fee liability (at fair value)	1,800		$ 1,300
Servicing fees and other receivables	$ 11,700		$ 8,100
Capitalized cost amortization term	3 years

Revenue - Loan Servicing Rights

Revenue - Loan Servicing Rights (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Net gain (loss) related to loan servicing rights	$ (67)	$ 1,459

Revenue - Fees Collected (Detai

Revenue - Fees Collected (Details) - USD ($) $ in Thousands	3 Months Ended
Revenue - Fees Collected (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from fees, net	$ 116,170	$ 68,013
Collection agency fees
Disaggregation of Revenue [Line Items]
Revenue from fees, net	863	800
Borrower fees
Disaggregation of Revenue [Line Items]
Revenue from fees, net	$ 886	$ 517

Revenue - Interest Income and F

Revenue - Interest Income and Fair Value Adjustments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Interest income	$ 3,405	$ 9,183
Interest expense	(1,030)	(3,255)
Fair value and other adjustments, net	2,800	(9,947)
Total interest income and fair value adjustments, net	$ 5,175	(4,019)
Variable Interest Entity, Primary Beneficiary
Disaggregation of Revenue [Line Items]
Interest income		3,379
Interest expense		(569)
Fair value and other adjustments, net		(3,000)
Total interest income and fair value adjustments, net		$ (190)

Securitizations and Variable _3

Securitizations and Variable Interest Entities - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Restricted cash		$ 79,049	$ 60,514
Notes receivable and residual certificates (at fair value)
Variable Interest Entity [Line Items]
Loans, notes receivables, and residual certificates		16,033	19,074
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Restricted cash		19,440	12,371
Variable Interest Entity, Primary Beneficiary \| Notes receivable and residual certificates (at fair value)
Variable Interest Entity [Line Items]
Loans, notes receivables, and residual certificates		14,678	17,219
Variable Interest Entity, Primary Beneficiary \| Majority-owned Affiliates
Variable Interest Entity [Line Items]
Ownership percentage	20.00%
Variable Interest Entity, Primary Beneficiary \| Disposal Group, Disposed of by Sale, Not Discontinued Operations
Variable Interest Entity [Line Items]
Ownership interest sold	80.00%
Consideration received	$ 8,000
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Restricted cash		7,200	7,200
Variable Interest Entity, Not Primary Beneficiary \| Notes receivable and residual certificates (at fair value)
Variable Interest Entity [Line Items]
Loans, notes receivables, and residual certificates		$ 16,000	$ 18,900

Securitizations and Variable _4

Securitizations and Variable Interest Entities - Assets and Liabilities (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Assets	[1]	$ 488,588	$ 477,255
Liabilities	[1]	167,998	177,003
Net Assets		320,590	300,252
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets		86,723	104,992
Liabilities		21,499	42,296
Net Assets		65,224	62,696
Variable Interest Entity, Primary Beneficiary \| Warehouse Entities
Variable Interest Entity [Line Items]
Assets		47,329	71,530
Liabilities		16,394	35,109
Net Assets		30,935	36,421
Variable Interest Entity, Primary Beneficiary \| Majority-owned Affiliates
Variable Interest Entity [Line Items]
Assets		14,678	17,219
Liabilities		5,105	7,187
Net Assets		9,573	10,032
Variable Interest Entity, Primary Beneficiary \| Other Consolidated VIEs
Variable Interest Entity [Line Items]
Assets		24,716	16,243
Liabilities		0	0
Net Assets		24,716	16,243
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets		439,094	524,358
Liabilities		347,421	430,006
Net Assets		91,673	94,352
Maximum Exposure to Losses		23,248	26,141
Variable Interest Entity, Not Primary Beneficiary \| Securitizations
Variable Interest Entity [Line Items]
Assets		407,667	484,604
Liabilities		315,994	390,252
Net Assets		91,673	94,352
Maximum Exposure to Losses		21,893	24,434
Variable Interest Entity, Not Primary Beneficiary \| Upstart Network Trust
Variable Interest Entity [Line Items]
Assets		31,427	39,754
Liabilities		31,427	39,754
Net Assets		0	0
Maximum Exposure to Losses		$ 1,355	$ 1,707

[1]	The following table presents information on assets and liabilities related to variable interest entities (“VIEs”) that are consolidated by Upstart Holdings, Inc. at December 31, 2020 and March 31, 2021. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. The holders of the beneficial interests do not have recourse to the general credit of Upstart Holdings, Inc. The assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs and exclude intercompany balances that eliminate in consolidation. December 31, March 31, 2020 2021 Assets Restricted cash $ 12,371 $ 19,440 Loans (at fair value) 75,373 52,558 Notes receivable and residual certificates (at fair value) 17,219 14,678 Other assets 29 47 Total assets $ 104,992 $ 86,723 Liabilities Accounts payable $ 83 $ 71 Borrowings 42,181 21,428 Other liabilities 32 — Total liabilities $ 42,296 $ 21,499

Fair Value Measurement - Assets

Fair Value Measurement - Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets
Loan servicing assets	$ 8,734	$ 6,831
Liabilities
Loan servicing liabilities	10,853	8,254
Fair Value, Inputs, Level 3
Assets
Loans	57,189	78,460
Notes receivable and residual certificates	16,033	19,074
Loan servicing assets	8,734	6,831
Total assets	81,956	104,365
Liabilities
Loan servicing liabilities	10,853	8,254
Trailing fee liabilities	1,775	1,276
Total liabilities	$ 12,628	$ 9,530

Fair Value Measurement - Loans

Fair Value Measurement - Loans Held (Details) - Fair Value, Inputs, Level 3 - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale	$ 28,794	$ 60,232
Loans held-for-investment	28,395	18,228
Total	$ 57,189	$ 78,460

Fair Value Measurement - Measur

Fair Value Measurement - Measurement Inputs (Details) - Valuation Technique, Discounted Cash Flow - Fair Value, Inputs, Level 3	Mar. 31, 2021	Dec. 31, 2020
Minimum \| Discount rate \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.0352	0.0680
Minimum \| Discount rate \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.0301	0.0301
Minimum \| Credit risk rate \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.0021	0.0036
Minimum \| Credit risk rate \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.0004	0.0004
Minimum \| Prepayment rate \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.1269	0.1164
Minimum \| Prepayment rate \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.1560	0.1560
Maximum \| Discount rate \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.1660	0.1699
Maximum \| Discount rate \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.1400	0.1400
Maximum \| Credit risk rate \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.5231	0.5231
Maximum \| Credit risk rate \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.5069	0.5069
Maximum \| Prepayment rate \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.7853	0.7836
Maximum \| Prepayment rate \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.3688	0.3688
Weighted Average \| Discount rate \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.0674	0.0744
Weighted Average \| Discount rate \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.0583	0.0584
Weighted Average \| Credit risk rate \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.2309	0.1982
Weighted Average \| Credit risk rate \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.1740	0.1712
Weighted Average \| Prepayment rate \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.3368	0.3103
Weighted Average \| Prepayment rate \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.2767	0.2763

Fair Value Measurement - Sensit

Fair Value Measurement - Sensitivity of Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Loans (at fair value)
Discount rates
100 basis point increase	$ (714)	$ (979)
200 basis point increase	(1,415)	(1,939)
Expected credit loss rates on underlying loans
10% adverse change	(1,087)	(1,303)
20% adverse change	(2,126)	(2,611)
Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Aggregate fair value of loans purchased and held by ULT	57,189	78,460
Fair Value, Inputs, Level 3 \| Loans (at fair value)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Aggregate fair value of loans purchased and held by ULT	$ 57,189	$ 78,460

Fair Value Measurement - Loan_2

Fair Value Measurement - Loans Rollforward (Details) - Fair Value, Inputs, Level 3 - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Loans (at fair value)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 78,460	$ 232,305
Reclassification of loans from HFI to HFS	0	0
Purchases of loans	31,187	100,679
Sale of loans	(46,469)	(94,949)
Purchase of loans for immediate resale to investors	1,294,634	848,540
Immediate resale to investors	(1,294,634)	(848,540)
Repayments received	(5,639)	(23,030)
Changes in fair value recorded in earnings	(201)	(14,443)
Other changes	(149)	39
Fair value, ending balance	57,189	200,601
Loan Held For Sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	60,232	0
Reclassification of loans from HFI to HFS	(26)	125,297
Purchases of loans	18,240	97,924
Sale of loans	(46,469)	(94,949)
Purchase of loans for immediate resale to investors	1,294,634	848,540
Immediate resale to investors	(1,294,634)	(848,540)
Repayments received	(3,310)	(6,446)
Changes in fair value recorded in earnings	357	(5,281)
Other changes	(230)	(34)
Fair value, ending balance	28,794	116,511
Loans Held For Investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	18,228	141,555
Reclassification of loans from HFI to HFS	26	(125,297)
Purchases of loans	12,947	2,755
Sale of loans	0	0
Purchase of loans for immediate resale to investors	0	0
Immediate resale to investors	0	0
Repayments received	(2,329)	(1,311)
Changes in fair value recorded in earnings	(558)	(1,019)
Other changes	81	75
Fair value, ending balance	28,395	16,758
Securitized Loans Held For Investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	0	90,750
Reclassification of loans from HFI to HFS	0	0
Purchases of loans	0	0
Sale of loans	0	0
Purchase of loans for immediate resale to investors	0	0
Immediate resale to investors	0	0
Repayments received	0	(15,273)
Changes in fair value recorded in earnings	0	(8,143)
Other changes	0	(2)
Fair value, ending balance	$ 0	$ 67,332

Fair Value Measurement - Narrat

Fair Value Measurement - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Average effect of fair value of hypothetical 20% adverse change in expected credit loss rates (in percent)	17.00%
Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes receivable and residual certificates	$ 16,033	$ 19,074
Fair Value, Inputs, Level 3 \| Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Average effect on fair value of a 100 basis point increase in discount rates (in percent)	1.05%	1.23%
Average effect on fair value of a 200 basis point increase in discount rates (in percent)	2.08%	2.36%
Fair Value, Inputs, Level 3 \| Minimum \| Discount rate \| Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trailing fees liability, measurement input	0.0352
Fair Value, Inputs, Level 3 \| Minimum \| Credit risk rate \| Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trailing fees liability, measurement input	0.0021
Fair Value, Inputs, Level 3 \| Maximum \| Discount rate \| Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trailing fees liability, measurement input	0.1660
Fair Value, Inputs, Level 3 \| Maximum \| Credit risk rate \| Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trailing fees liability, measurement input	0.5231

Fair Value Measurement - Note R

Fair Value Measurement - Note Receivable Rollforward (Details) - Notes Receivable - Fair Value, Inputs, Level 3 - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 19,074	$ 34,116
Purchases and issuances of securitization notes and residual certificates		4
Repayments and settlements	(3,119)	(4,028)
Changes in fair value recorded in earnings	78	(3,196)
Fair value, ending balance	$ 16,033	$ 26,896

Fair Value Measurement - Fair V

Fair Value Measurement - Fair Value Assumptions (Details) - Fair Value, Inputs, Level 3 - Valuation Technique, Discounted Cash Flow	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Minimum
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Discount rate	15.00%	15.00%
Credit Risk Rate	0.03%	0.03%
Market-servicing rate	0.75%	0.75%
Prepayment rate	8.61%	9.07%
Maximum
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Discount rate	35.00%	35.00%
Credit Risk Rate	52.78%	52.78%
Market-servicing rate	0.75%	0.75%
Prepayment rate	88.79%	89.01%
Weighted Average
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Discount rate	22.88%	22.69%
Credit Risk Rate	17.73%	17.19%
Market-servicing rate	0.75%	0.75%
Prepayment rate	32.43%	31.62%

Fair Value Measurement - Loan S

Fair Value Measurement - Loan Servicing Sensitivity (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Loan servicing assets	$ 8,734	$ 6,831
Loan servicing liabilities	10,853	8,254
Fair Value, Inputs, Level 3
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Loan servicing assets	8,734	6,831
Loan servicing liabilities	10,853	8,254
Fair Value, Inputs, Level 3 \| Loan Servicing Liabilities
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Loan servicing liabilities	10,853	8,254	$ 5,906	$ 5,140
10% market-servicing rates increase	24,928	22,974
20% market-servicing rates increase	49,857	45,948
10% adverse change	5,773	2,491
20% adverse change	2,825	5,089
Fair Value, Inputs, Level 3 \| Loan Servicing Assets
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Loan servicing assets	8,734	6,831	$ 6,622	$ 4,725
10% market-servicing rates increase	(20,061)	(19,013)
20% market-servicing rates increase	(40,122)	(38,027)
10% adverse change	(4,646)	(2,061)
20% adverse change	$ (2,273)	$ (4,212)

Fair Value Measurement - Loan_3

Fair Value Measurement - Loan Servicing Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Servicing Asset at Fair Value, Amount [Roll Forward]
Fair value, beginning balance	$ 6,831
Fair value, ending balance	8,734
Servicing Liability at Fair Value, Amount [Roll Forward]
Fair value, beginning balance	8,254
Fair value, ending balance	10,853
Fair Value, Inputs, Level 3
Servicing Asset at Fair Value, Amount [Roll Forward]
Fair value, beginning balance	6,831
Fair value, ending balance	8,734
Servicing Liability at Fair Value, Amount [Roll Forward]
Fair value, beginning balance	8,254
Fair value, ending balance	10,853
Fair Value, Inputs, Level 3 \| Loan Servicing Liabilities
Servicing Liability at Fair Value, Amount [Roll Forward]
Fair value, beginning balance	8,254	$ 5,140
Sale of loans	3,519	1,246
Changes in fair value recorded in earnings	(920)	(480)
Fair value, ending balance	10,853	5,906
Loan Servicing Assets \| Fair Value, Inputs, Level 3
Servicing Asset at Fair Value, Amount [Roll Forward]
Fair value, beginning balance	6,831	4,725
Sale of loans	3,452	2,705
Changes in fair value recorded in earnings	(1,549)	(808)
Fair value, ending balance	$ 8,734	$ 6,622

Fair Value Measurement - Traili

Fair Value Measurement - Trailing Fee Rollforward (Details) - Fair Value, Inputs, Level 3 - Trailing Fee Liabilities - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, beginning balance	$ 1,276	$ 504
Issuances	669	312
Repayments and settlements	(170)	(54)
Fair value, ending balance	$ 1,775	$ 762

Loans at Fair Value (Details)

Loans at Fair Value (Details) - Loans (at fair value) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Outstanding principal balance	$ 76,573	$ 97,497
Net fair value and accrued interest adjustments	(19,384)	(19,037)
Fair value	57,189	78,460
Loans > 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Outstanding principal balance	3,592	2,018
Net fair value and accrued interest adjustments	(3,577)	(2,002)
Fair value	$ 15	$ 16

Balance Sheet Components - Othe

Balance Sheet Components - Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Other Assets [Abstract]
Servicing fees and other receivables	$ 18,134	$ 11,656
Deposits	8,165	7,947
Prepaid expenses	14,203	6,009
Loan servicing assets (at fair value)	8,734	6,831
Other assets	2,701	7,603
Total other assets	$ 51,937	$ 40,046

Balance Sheet Components - Prop

Balance Sheet Components - Property Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property, equipment, and software	$ 14,606	$ 13,724
Accumulated depreciation and amortization	(4,508)	(3,692)
Property, Plant and Equipment, Net	10,098	10,032
Capitalized internally developed software balances, net of accumulated amortization	6,000	6,000
Internally developed software
Property, Plant and Equipment [Line Items]
Total property, equipment, and software	8,362	7,906
Computer equipment
Property, Plant and Equipment [Line Items]
Total property, equipment, and software	1,711	1,285
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property, equipment, and software	1,770	1,770
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property, equipment, and software	$ 2,763	$ 2,763

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Accrued expenses	$ 19,791	$ 10,974
Accrued payroll	6,282	13,834
Loan servicing liabilities (at fair value)	10,853	8,254
Trailing fee liability (at fair value)	1,775	1,276
Other liabilities	4,168	1,331
Total accrued expenses and other liabilities	$ 42,869	$ 35,669

Borrowings - Summary (Details)

Borrowings - Summary (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Borrowings [Line Items]
Total payments due	$ 41,928	$ 62,681
Unamortized debt discount	(37)	(55)
Total borrowings	41,891	62,626
Term loans
Schedule of Borrowings [Line Items]
Total payments due	15,000	15,000
UNI credit facility \| Revolving credit facility
Schedule of Borrowings [Line Items]
Total payments due	5,500	5,500
Warehouse credit facilities \| Revolving credit facility
Schedule of Borrowings [Line Items]
Total payments due	16,323	34,994
Risk retention funding loans
Schedule of Borrowings [Line Items]
Total payments due	$ 5,105	$ 7,187

Borrowings - Narrative (Details

Borrowings - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended
Borrowings - Narrative (Details) - USD ($) $ in Thousands	Oct. 31, 2018	Sep. 30, 2018	Nov. 30, 2015	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2019
Schedule of Borrowings [Line Items]
Outstanding borrowings				$ 41,928	$ 62,681
Mezzanine Loan
Schedule of Borrowings [Line Items]
Debt, face amount	$ 15,000
Mezzanine Loan \| Maximum
Schedule of Borrowings [Line Items]
Stated interest rate	10.00%
UNI credit facility \| Revolving credit facility
Schedule of Borrowings [Line Items]
Maximum borrowing capacity		$ 5,500
Outstanding borrowings				5,500	5,500
UNI credit facility \| Maximum \| Revolving credit facility
Schedule of Borrowings [Line Items]
Stated interest rate		4.25%
Warehouse credit facilities \| Revolving credit facility
Schedule of Borrowings [Line Items]
Maximum borrowing capacity			$ 100,000
Outstanding borrowings				$ 16,323	$ 34,994
Redemption price (in percent)			100.00%
Minimum utilization requirement			$ 35,000
Maximum advance rate (in percent)				80.00%	80.00%
Risk retention funding loans
Schedule of Borrowings [Line Items]
Outstanding borrowings				$ 5,105	$ 7,187
Assets pledged as collateral				10,800	12,600
2018-2 RR Financing Agreement
Schedule of Borrowings [Line Items]
Stated interest rate	4.00%
2019-2 RR Financing Agreement
Schedule of Borrowings [Line Items]
Stated interest rate						4.33%
Outstanding borrowings				$ 5,100	$ 6,600
Prime Rate \| Mezzanine Loan \| Minimum
Schedule of Borrowings [Line Items]
Basis spread on variable rate (in percent)	5.25%
Prime Rate \| UNI credit facility \| Minimum \| Revolving credit facility
Schedule of Borrowings [Line Items]
Basis spread on variable rate (in percent)		1.00%
London Interbank Offered Rate (LIBOR) \| Warehouse credit facilities \| Minimum \| Revolving credit facility
Schedule of Borrowings [Line Items]
Basis spread on variable rate (in percent)			335.00%
London Interbank Offered Rate (LIBOR) \| Warehouse credit facilities \| Maximum \| Revolving credit facility
Schedule of Borrowings [Line Items]
Basis spread on variable rate (in percent)			400.00%

Borrowings - Assets Pledged as

Borrowings - Assets Pledged as Collateral (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Borrowings [Line Items]
Outstanding borrowings	$ 41,928	$ 62,681
Restricted cash	79,049	60,514
Variable Interest Entity, Primary Beneficiary
Schedule of Borrowings [Line Items]
Restricted cash	19,440	12,371
Warehouse credit facilities \| Revolving credit facility
Schedule of Borrowings [Line Items]
Outstanding borrowings	16,323	34,994
Warehouse credit facilities \| Revolving credit facility \| Variable Interest Entity, Primary Beneficiary
Schedule of Borrowings [Line Items]
Outstanding borrowings	16,323	34,994
Aggregate outstanding principal of loans pledged as collateral	28,854	59,709
Aggregate fair value of loans purchased and held by ULT	28,795	60,231
Restricted cash	$ 18,487	$ 11,270

Borrowings - Maturity (Details)

Borrowings - Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
Remainder of 2021	$ 20,500
2022	16,357
2023	5,071
2024	0
2025	0
Total	$ 41,928	$ 62,681

Common Stock and Common Stock_3

Common Stock and Common Stock Warrants - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 01, 2020	Oct. 31, 2018	Mar. 31, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Common stock, authorized (in shares)			700,000,000	700,000,000
Common stock, par value (in dollars per share)			$ 0.0001	$ 0.0001
Stock warrants issued to purchase common stock (in shares)		75,000
Stock warrants issued, exercise price (in dollars per share)		$ 2.16
Stock warrants issued, contractual term		10 years
Stock warrants issued, required repurchase amount in event of IPO	$ 1.5
Stock warrants reclassified from liability to equity (in shares)				75,000
Stock warrants issued, termination period after closing qualified sale	30 days
Stock warrants issued, termination period after company IPO price is confirmed (in dollars per share)	10 days

Common Stock and Common Stock_4

Common Stock and Common Stock Warrants - Reserved Shares of Common Stock for Issuance (Details) - shares	Mar. 31, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Warrants to purchase common stock	0	75,000,000
Total	32,920,505,000	22,212,404,000
2020 Equity Incentive Plan \| Common stock
Class of Stock [Line Items]
Shares reserved of common stock for issuance	10,389,402,000	2,537,181,000
Options to purchase common stock
Class of Stock [Line Items]
Shares reserved of common stock for issuance	19,590,771,000	19,600,223,000
Unvested RSUs
Class of Stock [Line Items]
Shares reserved of common stock for issuance	827,192,000	0
ESPP
Class of Stock [Line Items]
Shares reserved of common stock for issuance	2,113,140,000	0

Equity Incentive Plans - Narrat

Equity Incentive Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Oct. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of options exercised		$ 65.7	$ 0.8
Fair value of options vested during period		3.6	$ 1
Unrecognized stock-based compensation expense related to unvested stock options		$ 77.3
Weighted Average
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)		$ 61.67	$ 5.23
Common stock \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase, percent of outstanding shares (percent)		5.00%
Common stock \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase (in shares)		15,000,000
2012 Equity Incentive Plan \| Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)		15,000,000
2020 Equity Incentive Plan \| Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)		10,389,402,000
ISOs and NSOs \| 2012 Equity Incentive Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price as a percent of estimated fair value (percent)				100.00%
Award vesting period				4 years
Required service period				3 years
ISOs and NSOs \| 2012 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				10 years
ISOs \| 2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stockholder ownership (percent)				10.00%
ISOs \| 2012 Equity Incentive Plan \| Minimum \| Greater Than 10% Stockholders
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price as a percent of estimated fair value (percent)				110.00%
Stock options \| Weighted Average
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of recognition		2 years 4 months 24 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Period of recognition		3 years 6 months
Unrecognized stock-based compensation expense		$ 82.1
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)		2,113,140
Period of recognition		4 months 24 days
Unrecognized stock-based compensation expense		$ 3.1
Purchase period	6 months
ESPP purchase price of common stock, percent of market price	85.00%

Equity Incentive Plans - Stock

Equity Incentive Plans - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balances at December 31, 2020	19,600,223,000
Options granted	606,830,000
Options exercised	(521,511,000)
Options cancelled and forfeited	(94,771,000)
Balances at March 31, 2021	19,590,771,000	19,600,223,000
Stock Options Weighted Average Exercise Price Per Share
Options outstanding, Weighted average exercise price per share - December 31, 2020 (in dollars per share)	$ 4,270
Options outstanding, Weighted average exercise price per share - March 31, 2021 (in dollars per share)	$ 7,420	$ 4,270
Stock Option Activity, Additional Disclosures
Options outstanding, Weighted average remaining contractual term	6 years 7 months 6 days	6 years 9 months 18 days
Options outstanding, Aggregate intrinsic value (in dollars)	$ 2,379,126	$ 715,084
Options exercisable, Number of options	11,309,977,000
Options exercisable, Weighted average exercise price per share (in dollars per share)	$ 1,650
Options exercisable, Weighted average remaining contractual term	4 years 10 months 24 days
Options exercisable, Aggregate intrinsic value (in dollars)	$ 1,438,789
Options vested and expected to vest	19,168,127,000
Options vested and expected to vest, Weighted Average Exercise Price Per Share (in dollars per share)	$ 6,950
Options vested and expected to vest, Weighted average remaining contractual term	6 years 6 months
Options vested and expected to vest, Aggregate intrinsic value (in dollars)	$ 2,336,779

Equity Incentive Plans - RSU Ac

Equity Incentive Plans - RSU Activity (Details) - RSUs	3 Months Ended
Equity Incentive Plans - RSU Activity (Details) - RSUs	Mar. 31, 2021$ / sharesshares
Stock Appreciation Rights Activity
Unvested at December 31, 2020	0
RSUs granted	835,307,000
RSUs vested	(342,000)
RSUs cancelled and forfeited	(7,773,000)
Unvested at March 31, 2021	827,192,000
Weighted Average Grant Date Fair Value
Granted, Weighted average grant date fair value per share (in dollars per share) \| $ / shares	$ 101.56
Vested, Weighted average grant date fair value per share (in dollars per share) \| $ / shares	81.56
Forfeited, Weighted average grant date fair value per share (in dollars per share) \| $ / shares	$ 124.14

Equity Incentive Plans - Weight

Equity Incentive Plans - Weighted-Average Assumptions (Details)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	63.12%	53.23%
Expected volatility, maximum	65.01%	55.35%
Risk free rate, minimum	0.62%	1.34%
Risk free rate, maximum	1.14%	1.50%
Dividend yield	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 18 days	5 years 4 months 24 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 10 months 24 days	10 years
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	7 months 6 days
Expected volatility	61.65%
Risk-free interest rate	0.09%
Dividend yield	0.00%

Equity Incentive Plans - Expens

Equity Incentive Plans - Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 8,622	$ 1,965
Stock options
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	5,120	1,965
RSUs
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	1,445	0
ESPP
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	2,057	0
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	753	284
Customer operations
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	752	199
Engineering and product development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	4,307	926
General, administrative, and other
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 2,810	$ 556

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Millions	3 Months Ended
Leases - Narrative (Details) $ in Millions	Mar. 31, 2021USD ($)optionToExtend
Leases [Abstract]
Number of options to renew \| optionToExtend	2
Renewal term	5 years
Letter of credit outstanding \| $	$ 2

Leases - Lease Liability Maturi

Leases - Lease Liability Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Remainder of 2021	$ 3,483
2022	5,221
2023	5,516
2024	2,567
2025	1,579
Thereafter	2,417
Total undiscounted lease payments	20,783
Less: Present value adjustment	(2,162)
Operating lease liabilities	$ 18,621	$ 19,432

Leases - Lease Expense (Details

Leases - Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
Leases - Lease Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Rent expense	$ 1,528	$ 1,269
Variable lease payments	299	355
Cash paid for amounts included in the measurement of lease liabilities	$ 1,057	$ 1,011
Weighted average remaining lease term (in years)	4 years 4 months 13 days
Weighted average discount rate	5.09%

Commitment and Contingencies (D

Commitment and Contingencies (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Loan purchase obligation	$ 82.4	$ 39.3
Obligation to Repurchase Loans \| Maximum
Loss Contingencies [Line Items]
Estimate of potential loss	$ 6,224	$ 5,180.7

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended
Income Taxes (Details)	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Net effective tax rate	1.96%	0.00%

Net Income Per Share Attribut_3

Net Income Per Share Attributable to Upstart Holdings, Inc. Common Stockholders - Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income attributable to Upstart Holdings, Inc. common stockholders	$ 10,102	$ 1,480
Less: noncumulative dividends to preferred stockholders	0	(1,480)
Net income attributable to common stockholders, basic and diluted	$ 10,102	$ 0
Denominator:
Weighted-average number of shares outstanding used in computing net income per share attributable to Upstart Holdings, Inc. common stockholders, basic (in shares)	73,629,122	14,625,267
Weighted-average effect of dilutive securities (in shares)	17,820,449	0
Weighted-average number of shares outstanding used in computing net income per share attributable to Upstart Holdings, Inc. common stockholders, diluted (in shares)	91,449,571	14,625,267
Net income per share attributable to Upstart Holdings, Inc. common stockholders, basic (in dollars per share)	$ 0.14	$ 0
Net income per share attributable to Upstart Holdings, Inc. common stockholders, diluted (in dollars per share)	$ 0.11	$ 0

Earnings Per Share - Antidiluti

Earnings Per Share - Antidilutive Securities (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities were excluded from the computation of diluted net income per share attributable to Upstart Holdings, Inc. common stockholders because including them would have been anti-dilutive	1,355,106,000	66,357,412
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities were excluded from the computation of diluted net income per share attributable to Upstart Holdings, Inc. common stockholders because including them would have been anti-dilutive	0	47,349,577
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities were excluded from the computation of diluted net income per share attributable to Upstart Holdings, Inc. common stockholders because including them would have been anti-dilutive	617,424,000	18,087,958
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities were excluded from the computation of diluted net income per share attributable to Upstart Holdings, Inc. common stockholders because including them would have been anti-dilutive	737,682,000	0
Warrants to purchase convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities were excluded from the computation of diluted net income per share attributable to Upstart Holdings, Inc. common stockholders because including them would have been anti-dilutive	0	600,208
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities were excluded from the computation of diluted net income per share attributable to Upstart Holdings, Inc. common stockholders because including them would have been anti-dilutive	0	319,669

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - USD ($) $ / shares in Units, $ in Millions	Apr. 13, 2021	Apr. 08, 2021
Subsequent Event [Line Items]
Consideration transferred		$ 98.8
Cash payments		$ 18
Offering price per share (in dollars per share)	$ 120
Net proceeds from sale of stock	$ 263.9
Underwriting discount	11
Offering expense	$ 1
Prodigy Software, Inc.
Subsequent Event [Line Items]
Equity interest issued (in shares)		650,767
Public Stock Offering
Subsequent Event [Line Items]
Shares sold in offering	2,000,000
Over-Allotment Option
Subsequent Event [Line Items]
Shares sold in offering	300,000