iRhythm (IRTC) 10-Q 4 May 23 2023 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2023	Apr. 24, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	001-37918
Entity Registrant Name	iRhythm Technologies, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8149544
Entity Address, Address Line One	699 8th Street Suite 600
Entity Address, City or Town	San Francisco,
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94103
City Area Code	415
Local Phone Number	632-5700
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		30,470,755
Title of 12(b) Security	Common Stock, Par Value $0.001 Per Share
Trading Symbol	IRTC
Security Exchange Name	NASDAQ
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001388658
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 52,804	$ 78,832
Short-term investments	123,533	134,312
Accounts receivable, net	49,557	49,918
Inventory	16,388	15,155
Prepaid expenses and other current assets	11,608	10,555
Total current assets	253,890	288,772
Property and equipment, net	82,208	75,670
Operating lease right-of-use assets	59,301	60,666
Goodwill	862	862
Total	25,440	22,252
Total assets	421,701	448,222
Current liabilities:
Accounts payable	9,778	7,517
Accrued liabilities	54,607	65,497
Deferred revenue	3,486	3,051
Operating lease liabilities, current portion	14,032	13,031
Total current liabilities	81,903	89,096
Debt, noncurrent portion	34,939	34,935
Other noncurrent liabilities	1,013	1,307
Operating lease liabilities, noncurrent portion	82,012	83,072
Total liabilities	199,867	208,410
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.001 par value - 5,000 shares authorized; none issued and outstanding at March 31, 2023 and December 31, 2022	0	0
Common stock, $0.001 par value - 100,000 shares authorized; 30,463 shares at March 31, 2023 and 30,193 at December 31, 2022 issued and outstanding	30	28
Additional paid-in capital	783,182	762,380
Accumulated other comprehensive loss	(69)	(396)
Accumulated deficit	(561,309)	(522,200)
Total stockholders’ equity	221,834	239,812
Total liabilities and stockholders’ equity	$ 421,701	$ 448,222

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	30,463,000	30,193,000
Common stock, shares outstanding (in shares)	30,463,000	30,193,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Revenue, net	$ 111,436	$ 92,378
Cost of revenue	35,755	30,619
Gross profit	75,681	61,759
Operating expenses:
Research and development	14,842	10,542
Selling, general and administrative	100,343	73,158
Impairment and restructuring charges	0	26,608
Total operating expenses	115,185	110,308
Loss from operations	(39,504)	(48,549)
Interest expense	(950)	(2,029)
Other income, net	1,432	16
Loss before income taxes	(39,022)	(50,562)
Income tax provision	87	47
Net loss	$ (39,109)	$ (50,609)
Net loss per common share, basic (in USD per share)	$ (1.29)	$ (1.71)
Net loss per common share, diluted (in USD per share)	$ (1.29)	$ (1.71)
Weighted-average shares, basic (in shares)	30,297,000	29,596,000
Weighted-average shares, diluted (in shares)	30,297,000	29,596,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (39,109)	$ (50,609)
Other comprehensive income (loss):
Net change in unrealized gain (loss) on short-term investments	327	(292)
Comprehensive loss	$ (38,782)	$ (50,901)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities
Net loss	$ (39,109)	$ (50,609)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	3,576	3,143
Stock-based compensation	18,251	13,903
Amortization of premium and accretion of discounts on investments, net	(1,137)	432
Provision for doubtful accounts and contractual allowances	21,425	14,022
Amortization of operating lease right-of-use assets	1,365	6,547
Impairment charges	0	23,164
Other	176	0
Changes in operating assets and liabilities:
Accounts receivable	(21,064)	(22,878)
Inventory	(1,404)	(2,377)
Prepaid expenses and other current assets	(1,053)	(146)
Other assets	(3,189)	(3,058)
Accounts payable	2,262	(5,308)
Accrued liabilities	(11,228)	(9,429)
Deferred revenue	435	(116)
Operating lease liabilities	(59)	(6,175)
Net cash used in operating activities	(30,753)	(38,885)
Cash flows from investing activities
Purchases of property and equipment	(8,423)	(5,572)
Purchases of short-term investments	(33,757)	(45,974)
Sales of short-term investments	0	15,019
Maturities of short-term investments	46,000	28,000
Net cash provided by (used in) investing activities	3,820	(8,527)
Cash flows from financing activities
Payment of loans	0	(21,389)
Proceeds from term loan	0	35,000
Proceeds from issuance of common stock in connection with employee equity incentive plans	905	1,076
Payments of issuance costs for long-term debt	0	(51)
Net cash provided by financing activities	905	14,636
Net decrease in cash and cash equivalents	(26,028)	(32,776)
Cash and cash equivalents, beginning of period	78,832	127,562
Cash and cash equivalents, end of period	52,804	94,786
Supplemental disclosures of cash flow information:
Interest paid	678	1,967
Cash taxes paid	8	0
Cash received from tenant improvement allowances	1,603	0
Non-cash investing and financing activities:
Property and equipment costs included in accounts payable and accrued liabilities	203	225
Right-of-use assets obtained in exchange for operating lease liabilities	0	7,666
Capitalized stock-based compensation	$ 1,648	$ 1,250

Condensed Consolidated Statem_4

Condensed Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2021		29,494,000
Beginning balance at Dec. 31, 2021	$ 279,515	$ 27	$ 685,594	$ (406,045)	$ (61)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with employee equity incentive plans, net (in shares)		275,000
Issuance of common stock in connection with employee equity incentive plans, net	1,076		1,076
Stock-based compensation	15,152		15,152
Net loss	(50,609)			(50,609)
Net change in unrealized gain (loss) on short-term investments	(292)				(292)
Ending balance (in shares) at Mar. 31, 2022		29,769,000
Ending balance at Mar. 31, 2022	$ 244,842	$ 27	701,822	(456,654)	(353)
Beginning balance (in shares) at Dec. 31, 2022	30,193,000	30,193,000
Beginning balance at Dec. 31, 2022	$ 239,812	$ 28	762,380	(522,200)	(396)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with employee equity incentive plans, net (in shares)	16,696	270,000
Issuance of common stock in connection with employee equity incentive plans, net	$ 905	$ 2	903
Stock-based compensation	19,899		19,899
Net loss	(39,109)			(39,109)
Net change in unrealized gain (loss) on short-term investments	$ 327				327
Ending balance (in shares) at Mar. 31, 2023	30,463,000	30,463,000
Ending balance at Mar. 31, 2023	$ 221,834	$ 30	$ 783,182	$ (561,309)	$ (69)

ORGANIZATION AND DESCRIPTION OF

ORGANIZATION AND DESCRIPTION OF BUSINESS	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
ORGANIZATION AND DESCRIPTION OF BUSINESS	ORGANIZATION AND DESCRIPTION OF BUSINESS iRhythm Technologies, Inc. (the “Company”) was incorporated in the state of Delaware in September 2006. The Company is a leading digital healthcare company that creates trusted solutions that detect, predict, and prevent disease. The Company's principal business is the design, development, and commercialization of device-based technology to provide remote cardiac monitoring services that it believes allow clinicians to diagnose certain arrhythmias quicker and with greater efficiency than other services that rely on traditional technology. Since first receiving clearance from the U.S. Food and Drug Administration (“FDA”) for the Company's technology in 2009, the Company has supported physician and patient use of its technology and provided remote cardiac monitoring services from its Medicare-enrolled independent diagnostic testing facilities (“IDTFs”) and its qualified technicians. The Company has provided the Zio remote cardiac monitoring services, including extended Holter, traditional Holter, and mobile cardiac telemetry (“MCT”) monitoring services (“Zio Services”), using the Zio Systems. The Company is headquartered in San Francisco, California, which also serves as a clinical center. The Company has additional clinical centers in Deerfield, Illinois and Houston, Texas and a manufacturing facility in Cypress, California. The Company formed wholly-owned subsidiaries in the United Kingdom in March 2016, in Singapore in June 2021, in Japan in June 2022 and in the Philippines in February 2023.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP have been condensed or omitted, and accordingly the balance sheet as of March 31, 2023, and related disclosures, have been derived from the audited consolidated financial statements at that date but do not include all of the information required by GAAP for complete consolidated financial statements. These unaudited condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for the fair statement of the Company’s unaudited condensed consolidated financial information. The results of operations for the three months ended March 31, 2023, are not necessarily indicative of the results to be expected for the year ending December 31, 2023, or for any other interim period or for any other future year. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto for the year ended December 31, 2022, included in the Company’s Annual Report on Form 10-K, filed with the SEC on February 23, 2023. Risks and Uncertainties Macroeconomic Factors and Supply Chain Constraints The Company’s operations and performance may vary based on worldwide economic and political conditions, which have been adversely impacted by continued global economic uncertainty, political instability, and military hostilities in multiple geographies, including the COVID-19 pandemic, the ongoing military conflict between Russia and Ukraine, domestic and global inflationary trends, rising interest rates, instability in the global banking system, global supply shortages, and a tightening labor market. For example, the Company has experienced staff shortages at its contact centers as a result of the COVID-19 pandemic and federal, state and local responses thereto. A severe or prolonged economic downturn or period of global political instability could drive hospitals and other healthcare professionals to tighten budgets and curtail spending, which could in turn negatively impact rates at which physicians prescribe the Company’s Zio Services. In addition, higher unemployment rates or reductions in employer-provided benefits plans could result in fewer commercially insured patients, resulting in a reduction in the Company’s margins and impairing the ability of uninsured patients to make timely payments. A weak or declining economy could also strain the Company’s suppliers, possibly resulting in supply delays and disruptions. There is also a risk that one or more of the Company’s current service providers, suppliers, or other partners may not survive such difficult economic times, which could directly affect the Company’s ability to attain its goals on schedule and on budget. If the current equity and credit markets deteriorate, it may make any necessary debt or equity financing more difficult, more costly, and more dilutive. The Company cannot predict the timing, strength, or duration of an economic downturn, instability, or recovery, whether worldwide, in the United States, or within its industry. The Company’s remote work arrangements resulting from the COVID-19 pandemic and subsequent decision to pursue a sublease for its San Francisco headquarters resulted in an impairment of its right of use asset and related leasehold improvements and furniture during the three months ended March 31, 2022, and the Company may incur additional impairment charges related to real property lease agreements. The Company is continuously reviewing its liquidity and anticipated capital requirements. The Company believes it will have adequate liquidity over the next 12 months to operate its business and to meet its cash requirements. As of March 31, 2023, the Company is in compliance with its debt covenants. Reimbursement The Company receives revenue for the Zio Services primarily from third-party payors, which include commercial payors and government agencies, such as the Centers for Medicare & Medicaid Services (“CMS”). Third-party payors require the Company to identify the service for which it is seeking reimbursement by using a Current Procedural Terminology (“CPT”) code set maintained by the American Medical Associations. These CPT codes are subject to periodic change and update, which will impact the reimbursement rates for the Company’s Zio Services. CMS updates the reimbursement rates for diagnostic tests performed by IDTFs annually via the Medicare Physician Fee Schedule, and effective January 1, 2023, CMS established national payment rates for the CPT codes the Company uses to report the long-term Holter monitoring services it performs with its Zio XT System: CPT codes 93247 (for wear-time of greater than 7 days and up to 15 days) and 93243 (for wear-time of greater than 48 hours and up to 7 days). Based on the relative value units CMS assigned to CPT codes 93247 and 93243, the national reimbursement rates for these services in 2023 are $243.65 and $231.79, respectively, and range from $247.59 to $334.46 and $235.54 to $318.17 for the Company’s Medicare-enrolled IDTF locations in Deerfield, Illinois, Houston, Texas, and San Francisco, California, when considering the geographic practice cost index for these locations. Because remote cardiac monitoring technology, including the Zio System, are rapidly evolving, there is a continuing risk that relative value units assigned, and reimbursement rates set, by CMS may not adequately reflect the value and expense of this technology and related monitoring services, and the Company cannot provide certainty that CMS will not reduce these rates in the future, which would adversely affect the Company’s financial results. Use of Estimates The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the periods presented. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, contractual allowances, allowance for doubtful accounts, the useful lives of property and equipment, the recoverability of long-lived assets including the estimated usage of the printed circuit board assemblies (“PCBAs”), the incremental borrowing rate for operating leases, accounting for income taxes, impairment of right-of-use ("ROU") assets, and various inputs used in estimating stock-based compensation. Actual results may differ from those estimates. Accounts Receivable, Allowance for Doubtful Accounts and Contractual Allowances Accounts receivable includes amounts due to the Company from healthcare institutions, third-party payors, and government payors and their related patients, as a result of the Company's normal business activities. Accounts receivable is reported on the unaudited condensed consolidated balance sheets net of an estimated allowance for doubtful accounts and contractual allowances. The Company establishes an allowance for doubtful accounts for estimated uncollectible receivables based on its assessment of the collectability of customer accounts and recognizes the provision as a component of selling, general and administrative expenses. The Company records a provision for contractual allowances based on the estimated differences between contracted amounts and expected collection rates. Such provisions are based on the Company's historical experience and are reported as a reduction of revenue. The Company regularly reviews the allowances by considering factors such as historical experience, credit quality, the age of the accounts receivable balances, and current economic conditions that may affect a customer’s ability to pay. The following table presents the changes in the allowance for doubtful accounts (in thousands): Three Months Ended Year Ended Three Months Ended Balance, beginning of period $ 18,475 $ 14,012 $ 14,012 Add: provision for doubtful accounts 5,326 17,191 4,413 Less: write-offs, net of recoveries and other adjustments (4,726) (12,728) (60) Balance, end of period $ 19,075 $ 18,475 $ 18,365 The following table presents the changes in the contractual allowance (in thousands): Three Months Ended Year Ended Three Months Ended Balance, beginning of period $ 41,389 $ 31,274 $ 31,274 Add: provision for contractual adjustments 16,099 41,158 9,609 Less: contractual adjustments (9,457) (31,043) (26) Balance, end of period $ 48,031 $ 41,389 $ 40,857 Concentrations of Risk Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and cash equivalents, investments and accounts receivable. Cash balances are deposited in financial institutions which, at times, may be in excess of federally insured limits. Cash equivalents are invested in highly rated money market funds. The Company invests in a variety of financial instruments, such as, but not limited to, U.S. government securities, corporate notes, commercial paper and, by policy, limits the amount of credit exposure with any one financial institution or commercial issuer. The Company has not experienced any material losses on its deposits of cash and cash equivalents or investments. Concentrations of credit risk with respect to accounts receivable are limited due to the large number of customers comprising the Company’s customer base and their dispersion across many geographies. The Company does not require collateral. The Company records an allowance for doubtful accounts based on the assessment of the collectability of customer accounts, considering factors such as historical experience, credit quality, the age of the accounts receivable balances, and current economic conditions that may affect a customer’s ability to pay. The Centers for Medicare and Medicaid Services (" CMS"), accounted for approximately 24% and 22% of the Company's revenue for the three months ended March 31, 2023 and 2022, respectively. CMS accounted for 21% and 22% of accounts receivable at March 31, 2023 and December 31, 2022, respectively. Inflationary Risk The Company continuously monitors the effects of inflationary factors, such as increases in cost of goods sold and selling and operating expenses, which may adversely affect its results of operations. Specifically, the Company may experience inflationary pressure affecting freight costs, the cost of the components for the Company’s Zio Services, overhead costs relating to maintenance of the Company’s facilities, and in the wages paid to its employees due to challenging labor market conditions. Competitive and regulatory conditions may restrict the Company’s ability to fully recover these costs through price increases. As a result, it may be difficult to fully offset the impact of persistent inflation. The Company’s inability or failure to do so could have a material adverse effect on its business, financial condition and results of operations or cause the Company to need to obtain additional capital in future earlier than anticipated. Supply Risk The Company relies on single-source vendors to supply some of its disposable housings, instruments and other materials used to manufacture the Zio patches and the adhesive that binds the Zio patch to a patient’s body. These components and materials are critical, and there could be a considerable delay in finding alternative sources of supply. A global semiconductor supply shortage is having wide-ranging effects across multiple industries. The supply shortage has impacted multiple suppliers that provide the PCBAs to the Company. The semiconductor supply shortage may have an impact on the Company until global supply is sufficient for global demand. Revenue Recognition The Company has developed a proprietary system that combines an FDA-cleared wire-free, patch-based, 14-day wearable biosensor that continuously records ECG data, with a proprietary cloud-based data analytic platform to help physicians monitor patients and diagnose arrhythmias. In addition, the Company has received CE-mark certification for Zio XT System and ZEUS algorithm. The Company currently offers three Zio System options—the Zio XT System, the Zio AT System, and the Zio Monitor System. The Zio XT System is a prescription-only, remote ECG monitoring system that consists of the Zio XT patch that records the electric signal from the heart continuously for up to 14 days and the ZEUS System, which supports the capture and analysis of ECG data recorded by the Zio XT patch at the end of the wear period, including specific arrhythmia events detected by the ZEUS algorithm. The final step in the Zio Services is the delivery of an electronic Zio report to the prescribing physician with a summary of findings. The Company’s Zio XT services are generally billable when the Zio report is issued to the physician. The Zio Monitor System is the next generation of the Zio XT System, and is a prescription-only, remote ECG monitoring system that consists of the Zio Monitor patch that records the electric signal from the heart continuously for up to 14 days and the ZEUS System, which supports the capture and analysis of ECG data recorded by the Zio Monitor patch at the end of the wear period, including specific arrhythmia events detected by the ZEUS algorithm. The Company’s Zio Monitor services are generally billable when the Zio report is issued to the physician. The Zio AT System is a prescription-only, remote ECG monitoring system that similarly consists of the Zio AT patch that records the electric signal from the heart continuously for up to 14 days and the ZEUS System, but which also incorporates the Zio AT wireless gateway that provides connectivity between the patch and the ZEUS System during the patient wear period. The wireless gateway, slightly larger than a smart phone, is provided to the patient at the time of Zio AT patch application and collects and transmits data from the Zio AT patch to the cloud via a LTE protocol. The Zio AT service revenue is recognized over the patient wear period and delivery of electronic Zio reports with two p erformance obligations. The Company recognizes as revenue the amount of consideration to which it expects to be entitled in exchange for performing the service. The consideration the Company is entitled to varies by portfolio, as further defined below, and includes estimates that require significant judgment by management. A unique aspect of healthcare is the involvement of multiple parties to the service transaction. In addition to the patient, often a third-party, for example a commercial or governmental payor or healthcare institution, will pay the Company for some or all of the service on the patient’s behalf. Separate contractual arrangements exist between the Company and third-party payors that establish amounts the third-party payor will pay on behalf of a patient for covered services rendered. A small portion of the Company’s transactions are covered by third-party payors with whom there is neither a contractual agreement nor an established amount that the third-party payor will pay. In determining the collectability and transaction price for its service, the Company considers factors such as insurance claims which are adjudicated as allowable under the applicable policy and payment history from both payors and patient out-of-pocket costs, payor coverage, whether there is a contract between the payor or healthcare institution and the Company, historical amount received for the service, and any current developments or changes that could impact reimbursement and healthcare institution payments. Certain of these factors are forms of variable consideration which are only included in the transaction price to the extent it is probable that a significant reversal of cumulative revenue will not occur when the uncertainty associated with the variable consideration is subsequently resolved. A summary of the payment arrangements with third-party payors and healthcare institutions is as follows: • Contracted third-party payors – The Company has contracts with negotiated prices for services provided to patients with commercial healthcare insurance coverage. • CMS – The Company has received IDTF approval from regional Medicare Administrative Contractors and will receive reimbursement per the relevant CPT code rates for the services rendered to the patient covered by CMS. • Healthcare institutions – Healthcare institutions are typically hospitals or physician practices in which the Company has negotiated amounts for its monitoring services, including certain governmental agencies such as the Veterans Administration and Department of Defense. • Non-contracted third-party payors – Non-contracted commercial and government payors often reimburse out-of-network rates provided under the relevant CPT codes on a case-by-case basis. The transaction price used for determining revenue recognition is based on factors including an average of the Company’s historical collection experience for its non-contracted services. This rate is reviewed at least quarterly. The Company is utilizing the portfolio approach practical expedient under ASC 606, Revenue from Contracts with Customers, whereby services provided under each of the above payor types form a separate portfolio. The Company accounts for the contracts within each portfolio as a collective group, rather than individual contracts. Based on history with these portfolios and the similar nature and characteristics of the patients within each portfolio, the Company has concluded that the financial statement effects are not materially different than if accounting for revenue on a contract-by-contract basis. For contracted and CMS portfolios, the Company recognizes revenue, net of contractual allowances, and recognizes an allowance for doubtful accounts for uncollectible patient accounts receivable. The transaction price is determined based on negotiated rates, and the Company has historical experience of collecting substantially all of these contracted rates. These contracts also impose a number of obligations regarding billing and other matters, and the Company’s noncompliance with a material term of such contracts may result in a denial of the claim. The Company accounts for denied claims as a form of variable consideration that is included as a reduction to the transaction price recognized as revenue. The Company makes estimates around the amount of denied claims within a reporting period, a process that requires management judgment. The estimated denied claims are based on historical information, and judgement includes the historical period utilized. The Company monitors the estimated denied claims against the latest available information, and subsequent changes to the estimated denied claims are recorded as an adjustment to revenue in the periods during which such changes occur. Delays in claims submissions could lead to an increase in denials if the Company misses the payors’ filing deadlines and could result in a reduction in the Company’s receipt of payments. Historical cash collection indicates that it is probable that substantially all of the transaction price, less the estimate of denied claims, will be received. Contracted payors may require that the Company bills patient co-payments and deductibles and from time to time the Company may not be able to collect such amounts due to credit risk. The Company provides for estimates of uncollectible patient accounts receivable, based upon historical experience where judgment includes the historical period utilized, at the time revenue is recognized, with such provisions presented as bad debt expense within the selling, general and administrative line item of the consolidated statement of operations. Adjustments to these estimates for actual experience are also recorded as an adjustment to bad debt expense. For healthcare institutions, the transaction price is determined based on negotiated rates, and the Company has historical experience collecting substantially all of these contracted rates. Historical cash collections indicate that it is probable that substantially all of the transaction price will be received. As such, the Company is not providing an implicit price concession but, rather, has chosen to accept the risk of default, and any subsequent uncollected amounts are recorded as bad debt expense to selling, general and administrative expense in the consolidated statements of operations. For non-contracted portfolios, the Company provides an implicit price concession due to the lack of a contracted rate with the underlying payor. As a result, the Company estimates the transaction price based on historical cash collections utilizing the expected value method. All subsequent adjustments to this transaction price are recorded to revenue. Stock-Based Compensation The Company measures the estimated fair values of its restricted stock units based on the closing price of the Company's stock on the grant date. For performance-based restricted stock units, the Company estimates the fair value based on the closing price of its stock on the grant date and, if the award includes a market condition, a Monte Carlo simulation model. In addition, for performance-based restricted stock units, the Company applies a probability assessment to determine the probable achievement of the performance-based metrics. Stock-based compensation expense is recognized over the requisite service period using the straight-line method and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company's stock-based compensation is reduced for the estimated forfeitures at the date of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. For restricted stock, the compensation cost for these awards is based on the closing price of the Company’s common stock on the date of grant, and recognized as compensation expense on a straight-line basis over the requisite service period. The Company recognizes compensation expense related to the Employee Stock Purchase Plan (“ESPP”) based on the estimated fair value of the options on the date of grant, net of estimated forfeitures. The Company estimates the grant date fair value, and the resulting stock-based compensation expense, using the Black-Scholes option pricing model for each purchase period. The grant date fair value is expensed on a straight-line basis over the offering period.

REVENUE

REVENUE	3 Months Ended
	Mar. 31, 2023
Revenue from Contract with Customer [Abstract]
REVENUE	REVENUE Disaggregation of Revenue The Company disaggregates revenue from contracts with customers by payor type. The Company believes these categories aggregate the payor types by nature, amount, timing and uncertainty of its revenue streams. Disaggregated revenue by payor type and major service line for three months ended March 31, 2023 and March 31, 2022 were as follows (in thousands, except percentages): Three Months Ended March 31, 2023 2022 Amount % of Revenue Amount % of Revenue Contracted third-party payors $ 61,907 56% $ 51,751 56% Centers for Medicare and Medicaid 26,491 24% 20,062 22% Healthcare institutions 15,781 14% 15,078 16% Non-contracted third-party payors 7,257 6% 5,487 6% Total $ 111,436 $ 92,378 Revenue generated from the United States comprised substantially all of the Company's revenue. No other country comprised 10% or greater of the Company's revenue during each of the three months ended March 31, 2023 and 2022. Contract Liabilities ASC 606, Revenue from Contracts with Customers, requires an entity to present a revenue contract as a contract liability when the Company has an obligation to transfer goods or services to a customer for which the Company has received consideration from the customer, or an amount of consideration from the customer is due and unconditional (whichever is earlier). Certain of the Company’s customers pay the Company directly for the Zio XT service upon shipment of devices. Such advance payments are contract liabilities and are recorded as deferred revenue when reports are delivered to the healthcare provider. During the three months ended March 31, 2023, $2.7 million relating to the contract liability balance at the beginning of 2023 was recognized as revenue. During the three months ended March 31, 2022, $2.7 million relating to the contract liability balance at the beginning of 2022 was recognized as revenue. Contract Costs Under ASC 340, Other Assets and Deferred Costs ("ASC 340"), the incremental costs of obtaining a contract with a customer are recognized as an asset. Incremental costs of obtaining a contract are those costs that an entity incurs to obtain a contract with a customer that it would not have incurred if the contract had not been obtained.

CASH EQUIVALENTS AND SHORT-TERM

CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS	3 Months Ended
	Mar. 31, 2023
Cash Equivalents And Investments [Abstract]
CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS	CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS The fair value of cash equivalents and short-term investments as of March 31, 2023 and December 31, 2022, were as follows (in thousands): March 31, 2023 Amortized Gross Unrealized Fair Value Gains Losses Money market funds $ 6,845 $ — $ — $ 6,845 U.S. government securities 123,602 65 (134) 123,533 Total cash equivalents and short-term investments $ 130,447 $ 65 $ (134) $ 130,378 Classified as: Cash equivalents $ 6,845 Short-term investments 123,533 Total cash equivalents and short-term investments $ 130,378 December 31, 2022 Amortized Gross Unrealized Fair Value Gains Losses Money market funds $ 24,263 $ — $ — $ 24,263 U.S. government securities 134,709 12 (409) 134,312 Total cash equivalents and short-term investments $ 158,972 $ 12 $ (409) $ 158,575 Classified as: Cash equivalents $ 24,263 Short-term investments 134,312 Total cash equivalents and short-term investments $ 158,575

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2023
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Company discloses and recognizes the fair value of its assets and liabilities using a hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The hierarchy gives the highest priority to valuations based upon unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to valuations based upon unobservable inputs that are significant to the valuation (Level 3 measurements). The guidance establishes three levels of the fair value hierarchy as follows: Level 1 —Inputs are unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 —Inputs (other than quoted market prices included in Level 1) are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life. Level 3 —Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The U.S. government securities are classified as Level 2 as they were valued based upon quoted market prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. The Company's interest-bearing obligation is classified as Level 2. As of March 31, 2023 the fair value of the Company’s outstanding interest-bearing obligation approximated the carrying value of $34.9 million. As of December 31, 2022, the fair value of the Company’s outstanding interest-bearing obligation approximated the carrying value of $34.9 million. The Company had no transfers between levels of the fair value hierarchy of its assets measured at fair value. The following tables present the fair value of the Company’s financial assets determined using the inputs defined above (in thousands): March 31, 2023 Level 1 Level 2 Level 3 Total Assets Money market funds $ 6,845 $ — $ — $ 6,845 U.S. government securities — 123,533 — 123,533 Total $ 6,845 $ 123,533 $ — $ 130,378 December 31, 2022 Level 1 Level 2 Level 3 Total Assets Money market funds $ 24,263 $ — $ — $ 24,263 U.S. government securities — 134,312 — 134,312 Total $ 24,263 $ 134,312 $ — $ 158,575

BALANCE SHEET DETAILS

BALANCE SHEET DETAILS	3 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BALANCE SHEET DETAILS	BALANCE SHEET DETAILS Inventory Inventory consisted of the following (in thousands): March 31, December 31, Raw materials $ 9,253 $ 9,338 Finished goods 7,135 5,817 Total $ 16,388 $ 15,155 Other Assets Other assets consisted of the following (in thousands): March 31, December 31, PCBAs $ 21,545 $ 18,599 Cloud computing arrangements 2,611 2,523 Other 1,284 1,130 Total $ 25,440 $ 22,252 The Company uses PCBAs in each wearable Zio XT patch and Zio AT patch, as well as the wireless gateway used in conjunction with the Zio AT patch. The PCBAs are used numerous times and have useful lives beyond one year. Each time a PCBA is used in a wearable Zio XT patch or Zio AT patch, a portion of the cost of the PCBA is recorded as a cost of revenue. Each time a wireless gateway is used with a Zio AT patch, a portion of the gateway is recorded as a cost of revenue. PCBAs, which are recorded as other assets, were $21.5 million and $18.6 million as of March 31, 2023, and December 31, 2022, respectively. The amortization was $1.4 million and $1.2 million for the three months ended March 31, 2023 and 2022, respectively. Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): March 31, December 31, Laboratory and manufacturing equipment $ 4,965 $ 4,911 Computer equipment and software 2,448 2,315 Furniture and fixtures 4,197 4,119 Leasehold improvements 23,533 23,144 Internal-use software 44,877 44,877 Internal-use software in development 35,919 28,069 Construction in progress 5,061 3,451 Total property and equipment, gross 121,000 110,886 Less: accumulated depreciation and amortization (38,792) (35,216) Total property and equipment, net $ 82,208 $ 75,670 Depreciation and amortization expense for the three months ended March 31, 2023 and 2022 was $3.6 million and $3.1 million, respectively, of which amortization related to internal-use software, was $2.7 million and $2.2 million, respectively. During the three months ended March 31, 2023, internal-use software increased by $7.9 million . This increase relates to the enhancements to the Company’s core technology, products and services and artificial intelligence, as well as investment in future technology, such as the Zio Monitor System, the Company's new biosensor technology platform, and the clinically-integrated ZEUS System for the Zio Watch. Accrued Liabilities Accrued liabilities consisted of the following (in thousands): March 31, December 31, Accrued payroll and related expenses $ 23,696 $ 34,752 Accrued vacation 9,484 8,608 Accrued expenses 8,186 7,006 Claims payable 4,648 4,464 Accrued employee share purchase plan contributions 3,068 1,045 Accrued state and foreign income and sales taxes 2,939 2,388 Accrued professional services fees 2,586 7,234 Total accrued liabilities $ 54,607 $ 65,497

IMPAIRMENT AND RESTRUCTURING CH

IMPAIRMENT AND RESTRUCTURING CHARGES	3 Months Ended
	Mar. 31, 2023
Restructuring and Related Activities [Abstract]
IMPAIRMENT AND RESTRUCTURING CHARGES	IMPAIRMENT AND RESTRUCTURING CHARGES During the three months ended March 31, 2023, there were no impairment and restructuring charges. In February 2022, the Company's board of directors (the “Board”) approved a restructuring plan ("Restructuring Plan") to allow it to effectively and efficiently scale its business, which resulted in severance and other employment related costs of $3.4 million during the three months ended March 31, 2022. Also in February 2022, the Board approved reducing the Company's leased space for its headquarters in San Francisco, California, by a total amount of leased square footage of approximately 50%. As a result, the Company recognized an impairment of its ROU asset and related leasehold improvements and furniture and fixtures in the amount of $23.2 million during the three months ended March 31, 2022. The Company's restructuring and impairment charges are described below (in thousands): Three Months Ended Restructuring charges $ 3,444 Impairment charges 23,164 Total $ 26,608 For further details, please refer to Note 7 “ Impairment and Restructuring ” included in the financial statements accompanying the Company’s Annual Report on Form 10-K for the year ended December 31, 2022. Restructuring The following table provides a summary of changes in the restructuring liabilities associated with the Restructuring Plan (in thousands): December 31, Charges Cash Payments March 31, Employee severance $ 394 $ — $ (394) $ — Total $ 394 $ — $ (394) $ —

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Purchase Commitments The Company is party to various purchase arrangements related to its manufacturing and research and development activities. During the quarter ended March 31, 2023, there were no material changes to purchase commitments from those disclosed in the financial statements accompanying the Company’s Annual Report on Form 10-K for the year ended December 31, 2022, in Note 8, “ Commitments and Contingencies .” Leases The Company leases office, manufacturing, and clinical centers under non-cancelable operating leases which expire on various dates through 2031. These leases generally contain scheduled rent increases or escalation clauses and renewal options. Operating lease ROU assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. The operating lease ROU assets also include any lease payments made to the lessor at or before the commencement date as well as variable lease payments which are based on a consumer price index. The Company is also subject to variable lease payments related to janitorial services and electricity which are not included in the operating lease ROU asset as they are based on actual usage. The Company recognizes operating lease expenses, generally on a straight-line basis over the lease period. During the three months ended March 31, 2023, there were no material changes to the leases from those described in Note 8, Commitments and Contingencies , included in the Company's Annual Report on Form 10-K for the year ended December 31, 2022. Contractual obligations under operating lease liabilities were as follows (in thousands): Year Ending December 31: 2023 (remainder of the year) $ 15,609 2024 20,586 2025 20,379 2026 20,131 2027 19,731 Thereafter 34,392 Total lease payments 130,828 Less: imputed interest (34,784) Total lease liabilities $ 96,044 Legal Proceedings From time to time, the Company is involved in claims and legal proceedings or investigations, that arise in the ordinary course of business. Such matters could have an adverse impact on the Company's reputation, business, and financial condition and divert the attention of its management from the operation of the Company's business. These matters are subject to many uncertainties and outcomes that are not predictable. On February 1, 2021, a putative class action lawsuit was filed in the United States District Court for the Northern District of California (the “Court”) alleging that the Company and its former Chief Executive Officer, Kevin M. King, violated Sections 10(b) and 20(a) of the Exchange Act and SEC Rule 10b-5 promulgated thereunder (“Securities Class Action Lawsuit”). On August 2, 2021, the lead plaintiff filed an amended complaint, and filed a further amended complaint on September 24, 2021. The amended complaint names as defendants, in addition to the Company and Mr. King, its former Chief Executive Officer, Michael J. Coyle, and former Chief Financial Officer and former Chief Operating Officer, Douglas J. Devine. The purported class in the amended complaint includes all persons who purchased or acquired the Company's common stock between August 4, 2020 and July 13, 2021, and seeks unspecified damages purportedly sustained by the class. On October 27, 2021, the Company filed a motion to dismiss the amended complaint. The motion to dismiss was fully briefed and the Court held a hearing on the motion on February 4, 2022, after which the Court took the matter under submission. On March 31, 2022, the Court issued an order granting the Company's motion to dismiss the Securities Class Action Lawsuit, without allowing plaintiff further leave to amend, and entered judgment in favor of the Company and the other defendants. On April 29, 2022, the plaintiff that filed the initial complaint in the action filed a notice of appeal. On September 7, 2022, the plaintiff-appellant filed its opening brief, and the Company filed a motion to dismiss for lack of standing to appeal and Article III standing on September 27, 2022. On October 17, 2022, the plaintiff filed its response to the Company's motion to dismiss, and the Company filed its reply in support of the motion to dismiss on November 3, 2022. The Company's motion to dismiss the appeal was denied without prejudice on December 8, 2022. The Company filed its responding brief on the appeal on February 16, 2023. The Company believes the Securities Class Action Lawsuit to be without merit and plan to defend itself vigorously. On March 26, 2021, the Company received a grand jury subpoena from the U.S. Attorney’s Office for the Northern District of California requesting information related to communications with the Food and Drug Administration and the Company's products and services. On September 14, 2021, the Company received a second subpoena requesting additional information. On April 4, 2023, the Company received a Subpoena Duces Tecum from the Consumer Protection Branch, Civil Division of the U.S. Department of Justice, requesting production of various documents regarding the Company’s products and services. The Company is cooperating fully on these matters. Development Agreement On September 3, 2019, the Company entered into a Development Collaboration Agreement with Verily Life Sciences LLC, an Alphabet company (“VLS”) and Verily Ireland Limited (“VIL” And together with VLS, “Verily”) (such Development Collaboration Agreement, as amended by Amendment No.1 dated April 26, 2021 and Amendment No.2 dated January 24, 2022, the “Development Agreement”). The Development Agreement involves joint development and production of intellectual property between the Company and Verily. Each participant has primary responsibility for certain aspects of development and approval, with all processes to be performed at each respective party’s own cost. Costs incurred by the Company in connection with the Development Agreement will be expensed as research and development expense in accordance with ASC 730, Research and Development . The Company and Verily will develop certain next-generation atrial fibrillation (“Afib”) screening, detection, or monitoring products pursuant to the Development Agreement, which products will involve combining Verily and the Company’s technology platforms and capabilities. Under the terms of the Development Agreement, the Company paid Verily an upfront fee of $5.0 million in 2019. In addition, the Company agreed to make additional cash payments to Verily up to an aggregate of $12.75 million in milestone payments upon achievement of various development and regulatory milestones over the term of the Development Agreement. The Company has achieved milestones tied to payments totaling $11.0 million to date and expects to make additional payments over the term of the Development Agreement of $1.75 million, subject to the achievement of certain development and regulatory milestones including provisioning of the Zio Watch to enable market evaluation scheduled to begin in 2023. No payment-triggering milestones were achieved during the three months ended March 31, 2023. The Development Agreement provides each party with licenses to use certain intellectual property of the other party for development activities in the field of Afib screening, detection, or monitoring. Ownership of developed intellectual property will be allocated to the Company or Verily depending on the subject matter of the underlying developed intellectual property, and, for certain subject matter, shall be jointly owned. Indemnifications In the ordinary course of business, the Company enters into agreements pursuant to which it agrees to indemnify customers, vendors, lessors, business partners, and other parties with respect to certain matters, including losses arising out of the breach of such agreements, services to be provided by the Company, or from intellectual property infringement claims made by third parties. Pursuant to such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has also entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by applicable law. The Company currently has directors’ and officers’ insurance. The Company has never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions, and believes that the estimated fair value of these indemnification obligations is not material and it has not accrued any amounts for these obligations.

DEBT

DEBT	3 Months Ended
	Mar. 31, 2023
Debt Disclosure [Abstract]
DEBT	DEBT In October 2018, the Company entered into the Third Amended and Restated Loan and Security Agreement (“SVB Loan Agreement”) with Silicon Valley Bank (“SVB”). Under the SVB Loan Agreement, the Company had borrowed $35.0 million and had made repayments through March 2022, at which time the outstanding balance was $18.5 million. On March 28, 2022, the Company entered into a Second Amendment (“2022 Amendment”) to its SVB Loan Agreement which provided for a term loans facility in the aggregate principal amount of up to $75.0 million (the “2022 Term Loans”), of which $35.0 million was borrowed at closing and a portion of the proceeds was used to pay in full the outstanding balance of $18.5 million under the SVB Loan Agreement. The remaining $40.0 million of 2022 Term Loans may be borrowed from time to time at the Company’s option, in increments of at least $10.0 million, through December 31, 2023. The Company will pay interest only on the 2022 Term Loans until April 1, 2025, when it will commence repaying the 2022 Term Loans in 24 equal consecutive monthly installments, with all obligations under the 2022 Term Loans maturing on March 1, 2027. Interest charged on the 2022 Term Loans will accrue at a floating per annum rate equal to the greater of: (A) the Prime Rate plus 0.25%; and (B) 3.50%. The Company is also required to pay fees on any prepayment of the 2022 Term Loans, ranging from 3.0% to 1.0% depending on the date of prepayment, and a final payment equal to 5.0% of the principal amount of the 2022 Term Loans drawn. Once repaid or prepaid, the 2022 Term Loans may not be reborrowed. The Company accounted for the refinancing as an extinguishment of the original loans and paid a fee of $1.8 million, which was included in interest expense on the Consolidated Statement of Operations and recorded the 2022 Term Loans, net of issuance costs. The issuance costs on the new loans are amortized over the term of the loan. The 2022 Amendment also amended the terms of the revolving credit line under the SVB Loan Agreement, which provided for an aggregate principal amount of $25.0 million, to: (i) extend the maturity date from August 1, 2023 to March 1, 2027, (ii) increase the letters of credit sublimit to $15.0 million and (iii) increase the cash management services sublimit to $15.0 million. Interest charged on the principal amount outstanding under the revolving credit line shall accrue at a floating per annum rate equal to the greater of (A) the Prime Rate plus 0.25% and (B) 3.50%. The Company is required to pay an annual fee equal to 0.15% of the revolving credit line. As of March 31, 2023, no loans were outstanding under the revolving credit line and the Company used $8.4 million in letters of credit. The 2022 Amendment also amended the SVB Loan Agreement to require the Company to comply, as of the last day of each fiscal quarter, with a quick ratio of at least 1.15 to 1.0 or minimum adjusted EBITDA trailing 6 months of at least $15.0 million. On March 10, 2023, SVB was closed by the California Department of Financial Protection and Innovation and the Federal Deposit Insurance Corporation (“ FDIC”) was appointed as receiver. On March 12, 2023, the U.S. Department of the Treasury, Federal Reserve Board, and FDIC released a joint statement announcing that the FDIC would complete its resolution of SVB in a manner that fully protected all depositors at SVB and that depositors would have access to all of their money starting March 13, 2023. On March 26, 2023, it was announced that First-Citizens Bank & Trust Company would assume all of SVB’s deposits and loans as of March 27, 2023. The Company continues to have access to the revolving credit line and letters of credit available pursuant to the SVB Loan Agreement and was in compliance with its loan covenants as of March 31, 2023. Future minimum payments Contractual obligations for the 2022 term loans comprise principal and interest payments as follows (in thousands): Year Ending December 31, 2023 (remainder of the year) $ 2,141 2024 2,847 2025 15,608 2026 18,623 2027 4,434 Total 43,653 Less: Amount representing interest (8,653) Less: Debt issuance costs (61) Principal payments $ 34,939

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2023
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXESThe Company recorded a tax provision related to its U.S. state taxes and the U.K. subsidiary during the three months ended March 31, 2023 and 2022. Due to the uncertainties surrounding the realization of the U.S. deferred tax assets through future taxable income, the Company has provided a full valuation allowance and, therefore, no benefit has been recognized for the net operating loss carryforwards and other deferred tax assets.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	3 Months Ended
	Mar. 31, 2023
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY Common Stock The Company’s amended and restated certificate of incorporation dated October 25, 2016, as amended, authorizes the Company to issue 100,000,000 shares of common stock with a par value of $0.001 per share and 5,000,000 shares of preferred stock with a par value of $0.001 per share. The holders of common stock are entitled to receive dividends whenever funds and assets are legally available and when declared by the Board, subject to the prior rights of holders of all series of convertible preferred stock outstanding. No dividends were declared through March 31, 2023. The Company had reserved shares of common stock for issuance as follows: March 31, December 31, Options issued and outstanding 311,497 328,193 Unvested restricted stock units and performance-based restricted stock units 2,522,894 2,025,755 Shares available for grant under future stock plans 7,072,322 7,822,637 Shares available for future issuance 9,906,713 10,176,585

EQUITY INCENTIVE PLAN AND STOCK

EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION	3 Months Ended
	Mar. 31, 2023
Share-Based Payment Arrangement [Abstract]
EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION	EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION A summary of awards available for grant under the Company’s 2016 Equity Incentive Plan is as follows: Shares Available for Grant Balance as of December 31, 2022 7,822,637 Awards granted (869,619) Awards forfeited 119,304 Balance as of March 31, 2023 7,072,322 Restricted Stock Units and Performance-Based Restricted Stock Units The fair value of restricted stock units (“RSUs”) and performance-based restricted stock units ("PRSUs") are based on the Company’s closing stock price on the date of grant. The fair value of market based PRSUs were estimated at the date of grant using the Monte-Carlo option pricing model. A summary is as follows: Restricted Stock Units Performance Based Restricted Stock Units and Market-Based Units Shares Underlying RSUs Weighted Average Grant Date Fair Value Shares Underlying PRSUs 1 Weighted Average Grant Date Fair Value Balance as of December 31, 2022 1,464,666 $ 111.16 561,089 $ 120.22 Granted 611,589 118.84 258,030 137.29 Vested (228,894) 125.73 (24,282) 107.05 Forfeited (55,690) 117.91 (63,614) 119.29 Balance as of March 31, 2023 1,791,671 $ 111.71 731,223 $ 126.76 1 Based on the maximum number of performance based restricted stock units in the key executive grant agreements, the actual number of units granted will be based on the annual unit volume CAGR as described below. As of March 31, 2023, there was total unamortized compensation costs of $157.2 million, net of estimated forfeitures, related to unrecognized RSU expense, which the Company expects to recognize over a weighted average period of 2.0 years. Aggregate intrinsic value of the RSUs was $222.2 million as of March 31, 2023. As of March 31, 2023, there was total unamortized compensation costs of $43.1 million, net of estimated forfeitures, related to unrecognized PRSU expense, which the Company expects to recognize over a weighted average period of 2.4 years. Aggregate intrinsic value of the PRSUs was $90.7 million as of March 31, 2023. PRSUs and Market-based RSUs The Company grants PRSUs to its key executives. PRSUs can be earned in accordance with the performance equity program for each respective grant. For further details on PRSUs granted in 2022 and prior years, please refer to those disclosed in the financial statements accompanying the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 in Note 13, “ Equity Incentive Plans .” In February 2023, the Company granted PRSUs (“February 2023 awards”) to be earned based on the CAGR calculated between fiscal year 2025's and fiscal year 2022's annual unit volume and measuring a minimum performance threshold of 15% to earn 50.0% of target, and a maximum threshold of 25% achieved to earn 200.0% of target. These February 2023 awards are subject to the recipient's continued employment through the vesting date of March 15, 2026. In addition, in February 2023, the Company granted market-based PRSUs to Senior Executive Officers. These PRSUs to be earned will be based on the CAGR calculated between fiscal year 2025's and fiscal year 2022's annual unit volume and measuring performance thresholds mentioned above, as well as a comparison of the S&P Healthcare Index to the Company's TSR. The grant date fair value of the TSR was based on the expected term of 2.9 years, interest risk free rate of 4.5%, implied volatility of 83.8% and no dividend yield. These February 2023 awards are subject to the Senior Executive Officers continued employment through the vesting date of March 15, 2026. Options The following table summarizes stock option activity during the three months ended March 31, 2023: Options Outstanding Options Weighted- Weighted- Aggregate Balance as of December 31, 2022 328,193 $ 43.00 4.43 $ 16,635 Options exercised (16,696) 54.06 Balance as of March 31, 2023 311,497 42.41 4.16 25,425 Options exercisable – March 31, 2023 311,497 $ 42.41 4.16 $ 25,425 There have been no options granted since December 31, 2019. As of March 31, 2023, the options were fully vested. Employee Stock Purchase Plan In October 2016, the Company’s Board of Directors and stockholders approved the 2016 Employee Stock Purchase Plan (“ESPP”). The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP provides for 12 month offering periods that contain two six-month purchase periods. At the end of each purchase period, employees purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last day of the purchase period. During the three months ended March 31, 2023, there was no purchase period and therefore no common stock was issued to employees participating in the ESPP and 2,206,279 shares were available for issuance under the ESPP. During the three months ended March 31, 2023 there were no material changes to the ESPP from those described in Note 13, Equity Incentive Plans , included in the Company's Annual Report on Form 10-K for the year ended December 31, 2022. As of March 31, 2023, the Company had $3.4 million of unrecognized compensation expense related to ESPP subscriptions that will be recognized over a weighted average period of 0.2 years. Stock-Based Compensation Expense The following table summarizes the total stock-based compensation expense included in the unaudited condensed consolidated statements of operations for the three months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, 2023 2022 Cost of revenue $ 564 $ 386 Research and development 2,387 1,495 Selling, general and administrative 15,300 12,022 Total stock-based compensation expense $ 18,251 $ 13,903

NET LOSS PER SHARE

NET LOSS PER SHARE	3 Months Ended
	Mar. 31, 2023
Earnings Per Share [Abstract]
NET LOSS PER SHARE	NET LOSS PER SHARE As the Company had net losses for the three months ended March 31, 2023 and 2022, all potential common shares were determined to be anti-dilutive. The following table sets forth the computation of the basic and diluted net loss per share during the three months ended March 31, 2023 and 2022 (in thousands, except per share data): Three Months Ended March 31, 2023 2022 Numerator: Net loss $ (39,109) $ (50,609) Denominator: Weighted-average shares used to compute net loss per common share, basic and diluted 30,297 29,596 Net loss per common share, basic and diluted $ (1.29) $ (1.71) The following outstanding shares of potentially dilutive securities have been excluded from diluted net loss per common share for the three months ended March 31, 2023 and 2022 because their inclusion would be anti-dilutive (in thousands): Three Months Ended March 31, 2023 2022 Options to purchase common stock 311 481 RSUs and PRSUs unvested 2,523 1,717 Total 2,834 2,198

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP have been condensed or omitted, and accordingly the balance sheet as of March 31, 2023, and related disclosures, have been derived from the audited consolidated financial statements at that date but do not include all of the information required by GAAP for complete consolidated financial statements. These unaudited condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for the fair statement of the Company’s unaudited condensed consolidated financial information. The results of operations for the three months ended March 31, 2023, are not necessarily indicative of the results to be expected for the year ending December 31, 2023, or for any other interim period or for any other future year.
Risks and Uncertainties	Risks and Uncertainties Macroeconomic Factors and Supply Chain Constraints The Company’s operations and performance may vary based on worldwide economic and political conditions, which have been adversely impacted by continued global economic uncertainty, political instability, and military hostilities in multiple geographies, including the COVID-19 pandemic, the ongoing military conflict between Russia and Ukraine, domestic and global inflationary trends, rising interest rates, instability in the global banking system, global supply shortages, and a tightening labor market. For example, the Company has experienced staff shortages at its contact centers as a result of the COVID-19 pandemic and federal, state and local responses thereto. A severe or prolonged economic downturn or period of global political instability could drive hospitals and other healthcare professionals to tighten budgets and curtail spending, which could in turn negatively impact rates at which physicians prescribe the Company’s Zio Services. In addition, higher unemployment rates or reductions in employer-provided benefits plans could result in fewer commercially insured patients, resulting in a reduction in the Company’s margins and impairing the ability of uninsured patients to make timely payments. A weak or declining economy could also strain the Company’s suppliers, possibly resulting in supply delays and disruptions. There is also a risk that one or more of the Company’s current service providers, suppliers, or other partners may not survive such difficult economic times, which could directly affect the Company’s ability to attain its goals on schedule and on budget. If the current equity and credit markets deteriorate, it may make any necessary debt or equity financing more difficult, more costly, and more dilutive. The Company cannot predict the timing, strength, or duration of an economic downturn, instability, or recovery, whether worldwide, in the United States, or within its industry. The Company’s remote work arrangements resulting from the COVID-19 pandemic and subsequent decision to pursue a sublease for its San Francisco headquarters resulted in an impairment of its right of use asset and related leasehold improvements and furniture during the three months ended March 31, 2022, and the Company may incur additional impairment charges related to real property lease agreements. The Company is continuously reviewing its liquidity and anticipated capital requirements. The Company believes it will have adequate liquidity over the next 12 months to operate its business and to meet its cash requirements. As of March 31, 2023, the Company is in compliance with its debt covenants. Reimbursement The Company receives revenue for the Zio Services primarily from third-party payors, which include commercial payors and government agencies, such as the Centers for Medicare & Medicaid Services (“CMS”). Third-party payors require the Company to identify the service for which it is seeking reimbursement by using a Current Procedural Terminology (“CPT”) code set maintained by the American Medical Associations. These CPT codes are subject to periodic change and update, which will impact the reimbursement rates for the Company’s Zio Services. CMS updates the reimbursement rates for diagnostic tests performed by IDTFs annually via the Medicare Physician Fee Schedule, and effective January 1, 2023, CMS established national payment rates for the CPT codes the Company uses to report the long-term Holter monitoring services it performs with its Zio XT System: CPT codes 93247 (for wear-time of greater than 7 days and up to 15 days) and 93243 (for wear-time of greater than 48 hours and up to 7 days). Based on the relative value units CMS assigned to CPT codes 93247 and 93243, the national reimbursement rates for these services in 2023 are $243.65 and $231.79, respectively, and range from $247.59 to $334.46 and $235.54 to $318.17 for the Company’s Medicare-enrolled IDTF locations in Deerfield, Illinois, Houston, Texas, and San Francisco, California, when considering the geographic practice cost index for these locations. Because remote cardiac monitoring technology, including the Zio System, are rapidly evolving, there is a continuing risk that relative value units assigned, and reimbursement rates set, by CMS may not adequately reflect the value and expense of this technology and related monitoring services, and the Company cannot provide certainty that CMS will not reduce these rates in the future, which would adversely affect the Company’s financial results.
Use of Estimates	Use of Estimates The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the periods presented. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, contractual allowances, allowance for doubtful accounts, the useful lives of property and equipment, the recoverability of long-lived assets including the estimated usage of the printed circuit board assemblies (“PCBAs”), the incremental borrowing rate for operating leases, accounting for income taxes, impairment of right-of-use ("ROU") assets, and various inputs used in estimating stock-based compensation. Actual results may differ from those estimates.
Accounts Receivable, Allowance for Doubtful Accounts and Contractual Allowances	Accounts Receivable, Allowance for Doubtful Accounts and Contractual Allowances Accounts receivable includes amounts due to the Company from healthcare institutions, third-party payors, and government payors and their related patients, as a result of the Company's normal business activities. Accounts receivable is reported on the unaudited condensed consolidated balance sheets net of an estimated allowance for doubtful accounts and contractual allowances. The Company establishes an allowance for doubtful accounts for estimated uncollectible receivables based on its assessment of the collectability of customer accounts and recognizes the provision as a component of selling, general and administrative expenses. The Company records a provision for contractual allowances based on the estimated differences between contracted amounts and expected collection rates. Such provisions are based on the Company's historical experience and are reported as a reduction of revenue. The Company regularly reviews the allowances by considering factors such as historical experience, credit quality, the age of the accounts receivable balances, and current economic conditions that may affect a customer’s ability to pay.
Concentrations of Risk	Concentrations of Risk Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and cash equivalents, investments and accounts receivable. Cash balances are deposited in financial institutions which, at times, may be in excess of federally insured limits. Cash equivalents are invested in highly rated money market funds. The Company invests in a variety of financial instruments, such as, but not limited to, U.S. government securities, corporate notes, commercial paper and, by policy, limits the amount of credit exposure with any one financial institution or commercial issuer. The Company has not experienced any material losses on its deposits of cash and cash equivalents or investments.
Inflationary Risk	Inflationary Risk The Company continuously monitors the effects of inflationary factors, such as increases in cost of goods sold and selling and operating expenses, which may adversely affect its results of operations. Specifically, the Company may experience inflationary pressure affecting freight costs, the cost of the components for the Company’s Zio Services, overhead costs relating to maintenance of the Company’s facilities, and in the wages paid to its employees due to challenging labor market conditions. Competitive and regulatory conditions may restrict the Company’s ability to fully recover these costs through price increases. As a result, it may be difficult to fully offset the impact of persistent inflation. The Company’s inability or failure to do so could have a material adverse effect on its business, financial condition and results of operations or cause the Company to need to obtain additional capital in future earlier than anticipated.
Supply Risk	Supply Risk The Company relies on single-source vendors to supply some of its disposable housings, instruments and other materials used to manufacture the Zio patches and the adhesive that binds the Zio patch to a patient’s body. These components and materials are critical, and there could be a considerable delay in finding alternative sources of supply. A global semiconductor supply shortage is having wide-ranging effects across multiple industries. The supply shortage has impacted multiple suppliers that provide the PCBAs to the Company. The semiconductor supply shortage may have an impact on the Company until global supply is sufficient for global demand.
Revenue Recognition	Revenue Recognition The Company has developed a proprietary system that combines an FDA-cleared wire-free, patch-based, 14-day wearable biosensor that continuously records ECG data, with a proprietary cloud-based data analytic platform to help physicians monitor patients and diagnose arrhythmias. In addition, the Company has received CE-mark certification for Zio XT System and ZEUS algorithm. The Company currently offers three Zio System options—the Zio XT System, the Zio AT System, and the Zio Monitor System. The Zio XT System is a prescription-only, remote ECG monitoring system that consists of the Zio XT patch that records the electric signal from the heart continuously for up to 14 days and the ZEUS System, which supports the capture and analysis of ECG data recorded by the Zio XT patch at the end of the wear period, including specific arrhythmia events detected by the ZEUS algorithm. The final step in the Zio Services is the delivery of an electronic Zio report to the prescribing physician with a summary of findings. The Company’s Zio XT services are generally billable when the Zio report is issued to the physician. The Zio Monitor System is the next generation of the Zio XT System, and is a prescription-only, remote ECG monitoring system that consists of the Zio Monitor patch that records the electric signal from the heart continuously for up to 14 days and the ZEUS System, which supports the capture and analysis of ECG data recorded by the Zio Monitor patch at the end of the wear period, including specific arrhythmia events detected by the ZEUS algorithm. The Company’s Zio Monitor services are generally billable when the Zio report is issued to the physician. The Zio AT System is a prescription-only, remote ECG monitoring system that similarly consists of the Zio AT patch that records the electric signal from the heart continuously for up to 14 days and the ZEUS System, but which also incorporates the Zio AT wireless gateway that provides connectivity between the patch and the ZEUS System during the patient wear period. The wireless gateway, slightly larger than a smart phone, is provided to the patient at the time of Zio AT patch application and collects and transmits data from the Zio AT patch to the cloud via a LTE protocol. The Zio AT service revenue is recognized over the patient wear period and delivery of electronic Zio reports with two p erformance obligations. The Company recognizes as revenue the amount of consideration to which it expects to be entitled in exchange for performing the service. The consideration the Company is entitled to varies by portfolio, as further defined below, and includes estimates that require significant judgment by management. A unique aspect of healthcare is the involvement of multiple parties to the service transaction. In addition to the patient, often a third-party, for example a commercial or governmental payor or healthcare institution, will pay the Company for some or all of the service on the patient’s behalf. Separate contractual arrangements exist between the Company and third-party payors that establish amounts the third-party payor will pay on behalf of a patient for covered services rendered. A small portion of the Company’s transactions are covered by third-party payors with whom there is neither a contractual agreement nor an established amount that the third-party payor will pay. In determining the collectability and transaction price for its service, the Company considers factors such as insurance claims which are adjudicated as allowable under the applicable policy and payment history from both payors and patient out-of-pocket costs, payor coverage, whether there is a contract between the payor or healthcare institution and the Company, historical amount received for the service, and any current developments or changes that could impact reimbursement and healthcare institution payments. Certain of these factors are forms of variable consideration which are only included in the transaction price to the extent it is probable that a significant reversal of cumulative revenue will not occur when the uncertainty associated with the variable consideration is subsequently resolved. A summary of the payment arrangements with third-party payors and healthcare institutions is as follows: • Contracted third-party payors – The Company has contracts with negotiated prices for services provided to patients with commercial healthcare insurance coverage. • CMS – The Company has received IDTF approval from regional Medicare Administrative Contractors and will receive reimbursement per the relevant CPT code rates for the services rendered to the patient covered by CMS. • Healthcare institutions – Healthcare institutions are typically hospitals or physician practices in which the Company has negotiated amounts for its monitoring services, including certain governmental agencies such as the Veterans Administration and Department of Defense. • Non-contracted third-party payors – Non-contracted commercial and government payors often reimburse out-of-network rates provided under the relevant CPT codes on a case-by-case basis. The transaction price used for determining revenue recognition is based on factors including an average of the Company’s historical collection experience for its non-contracted services. This rate is reviewed at least quarterly. The Company is utilizing the portfolio approach practical expedient under ASC 606, Revenue from Contracts with Customers, whereby services provided under each of the above payor types form a separate portfolio. The Company accounts for the contracts within each portfolio as a collective group, rather than individual contracts. Based on history with these portfolios and the similar nature and characteristics of the patients within each portfolio, the Company has concluded that the financial statement effects are not materially different than if accounting for revenue on a contract-by-contract basis. For contracted and CMS portfolios, the Company recognizes revenue, net of contractual allowances, and recognizes an allowance for doubtful accounts for uncollectible patient accounts receivable. The transaction price is determined based on negotiated rates, and the Company has historical experience of collecting substantially all of these contracted rates. These contracts also impose a number of obligations regarding billing and other matters, and the Company’s noncompliance with a material term of such contracts may result in a denial of the claim. The Company accounts for denied claims as a form of variable consideration that is included as a reduction to the transaction price recognized as revenue. The Company makes estimates around the amount of denied claims within a reporting period, a process that requires management judgment. The estimated denied claims are based on historical information, and judgement includes the historical period utilized. The Company monitors the estimated denied claims against the latest available information, and subsequent changes to the estimated denied claims are recorded as an adjustment to revenue in the periods during which such changes occur. Delays in claims submissions could lead to an increase in denials if the Company misses the payors’ filing deadlines and could result in a reduction in the Company’s receipt of payments. Historical cash collection indicates that it is probable that substantially all of the transaction price, less the estimate of denied claims, will be received. Contracted payors may require that the Company bills patient co-payments and deductibles and from time to time the Company may not be able to collect such amounts due to credit risk. The Company provides for estimates of uncollectible patient accounts receivable, based upon historical experience where judgment includes the historical period utilized, at the time revenue is recognized, with such provisions presented as bad debt expense within the selling, general and administrative line item of the consolidated statement of operations. Adjustments to these estimates for actual experience are also recorded as an adjustment to bad debt expense. For healthcare institutions, the transaction price is determined based on negotiated rates, and the Company has historical experience collecting substantially all of these contracted rates. Historical cash collections indicate that it is probable that substantially all of the transaction price will be received. As such, the Company is not providing an implicit price concession but, rather, has chosen to accept the risk of default, and any subsequent uncollected amounts are recorded as bad debt expense to selling, general and administrative expense in the consolidated statements of operations. For non-contracted portfolios, the Company provides an implicit price concession due to the lack of a contracted rate with the underlying payor. As a result, the Company estimates the transaction price based on historical cash collections utilizing the expected value method. All subsequent adjustments to this transaction price are recorded to revenue.
Stock-Based Compensation	Stock-Based Compensation The Company measures the estimated fair values of its restricted stock units based on the closing price of the Company's stock on the grant date. For performance-based restricted stock units, the Company estimates the fair value based on the closing price of its stock on the grant date and, if the award includes a market condition, a Monte Carlo simulation model. In addition, for performance-based restricted stock units, the Company applies a probability assessment to determine the probable achievement of the performance-based metrics. Stock-based compensation expense is recognized over the requisite service period using the straight-line method and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company's stock-based compensation is reduced for the estimated forfeitures at the date of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. For restricted stock, the compensation cost for these awards is based on the closing price of the Company’s common stock on the date of grant, and recognized as compensation expense on a straight-line basis over the requisite service period. The Company recognizes compensation expense related to the Employee Stock Purchase Plan (“ESPP”) based on the estimated fair value of the options on the date of grant, net of estimated forfeitures. The Company estimates the grant date fair value, and the resulting stock-based compensation expense, using the Black-Scholes option pricing model for each purchase period. The grant date fair value is expensed on a straight-line basis over the offering period.
Contract Liabilities	Contract Liabilities ASC 606, Revenue from Contracts with Customers, requires an entity to present a revenue contract as a contract liability when the Company has an obligation to transfer goods or services to a customer for which the Company has received consideration from the customer, or an amount of consideration from the customer is due and unconditional (whichever is earlier).
Contract Costs	Contract Costs Under ASC 340, Other Assets and Deferred Costs ("ASC 340"), the incremental costs of obtaining a contract with a customer are recognized as an asset. Incremental costs of obtaining a contract are those costs that an entity incurs to obtain a contract with a customer that it would not have incurred if the contract had not been obtained.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Schedule of Changes in Allowance for Doubtful Accounts	The following table presents the changes in the allowance for doubtful accounts (in thousands): Three Months Ended Year Ended Three Months Ended Balance, beginning of period $ 18,475 $ 14,012 $ 14,012 Add: provision for doubtful accounts 5,326 17,191 4,413 Less: write-offs, net of recoveries and other adjustments (4,726) (12,728) (60) Balance, end of period $ 19,075 $ 18,475 $ 18,365
Schedule of Changes in Contractual Allowance	The following table presents the changes in the contractual allowance (in thousands): Three Months Ended Year Ended Three Months Ended Balance, beginning of period $ 41,389 $ 31,274 $ 31,274 Add: provision for contractual adjustments 16,099 41,158 9,609 Less: contractual adjustments (9,457) (31,043) (26) Balance, end of period $ 48,031 $ 41,389 $ 40,857

REVENUE (Tables)

REVENUE (Tables)	3 Months Ended
	Mar. 31, 2023
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregated Revenue by Payor Type and Major Service	Disaggregated revenue by payor type and major service line for three months ended March 31, 2023 and March 31, 2022 were as follows (in thousands, except percentages): Three Months Ended March 31, 2023 2022 Amount % of Revenue Amount % of Revenue Contracted third-party payors $ 61,907 56% $ 51,751 56% Centers for Medicare and Medicaid 26,491 24% 20,062 22% Healthcare institutions 15,781 14% 15,078 16% Non-contracted third-party payors 7,257 6% 5,487 6% Total $ 111,436 $ 92,378

CASH EQUIVALENTS AND SHORT-TE_2

CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS (Tables)	3 Months Ended
	Mar. 31, 2023
Cash Equivalents And Investments [Abstract]
Schedule of Cash Equivalents and Short-Term Investments	The fair value of cash equivalents and short-term investments as of March 31, 2023 and December 31, 2022, were as follows (in thousands): March 31, 2023 Amortized Gross Unrealized Fair Value Gains Losses Money market funds $ 6,845 $ — $ — $ 6,845 U.S. government securities 123,602 65 (134) 123,533 Total cash equivalents and short-term investments $ 130,447 $ 65 $ (134) $ 130,378 Classified as: Cash equivalents $ 6,845 Short-term investments 123,533 Total cash equivalents and short-term investments $ 130,378 December 31, 2022 Amortized Gross Unrealized Fair Value Gains Losses Money market funds $ 24,263 $ — $ — $ 24,263 U.S. government securities 134,709 12 (409) 134,312 Total cash equivalents and short-term investments $ 158,972 $ 12 $ (409) $ 158,575 Classified as: Cash equivalents $ 24,263 Short-term investments 134,312 Total cash equivalents and short-term investments $ 158,575

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Company's Financial Assets and Liabilities	The following tables present the fair value of the Company’s financial assets determined using the inputs defined above (in thousands): March 31, 2023 Level 1 Level 2 Level 3 Total Assets Money market funds $ 6,845 $ — $ — $ 6,845 U.S. government securities — 123,533 — 123,533 Total $ 6,845 $ 123,533 $ — $ 130,378 December 31, 2022 Level 1 Level 2 Level 3 Total Assets Money market funds $ 24,263 $ — $ — $ 24,263 U.S. government securities — 134,312 — 134,312 Total $ 24,263 $ 134,312 $ — $ 158,575

BALANCE SHEET DETAILS (Tables)

BALANCE SHEET DETAILS (Tables)	3 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Inventory Components	Inventory consisted of the following (in thousands): March 31, December 31, Raw materials $ 9,253 $ 9,338 Finished goods 7,135 5,817 Total $ 16,388 $ 15,155
Schedule of Other Assets	Other assets consisted of the following (in thousands): March 31, December 31, PCBAs $ 21,545 $ 18,599 Cloud computing arrangements 2,611 2,523 Other 1,284 1,130 Total $ 25,440 $ 22,252
Schedule of Property and Equipment, Net Components	Property and equipment, net consisted of the following (in thousands): March 31, December 31, Laboratory and manufacturing equipment $ 4,965 $ 4,911 Computer equipment and software 2,448 2,315 Furniture and fixtures 4,197 4,119 Leasehold improvements 23,533 23,144 Internal-use software 44,877 44,877 Internal-use software in development 35,919 28,069 Construction in progress 5,061 3,451 Total property and equipment, gross 121,000 110,886 Less: accumulated depreciation and amortization (38,792) (35,216) Total property and equipment, net $ 82,208 $ 75,670
Schedule of Accrued Liabilities Components	Accrued liabilities consisted of the following (in thousands): March 31, December 31, Accrued payroll and related expenses $ 23,696 $ 34,752 Accrued vacation 9,484 8,608 Accrued expenses 8,186 7,006 Claims payable 4,648 4,464 Accrued employee share purchase plan contributions 3,068 1,045 Accrued state and foreign income and sales taxes 2,939 2,388 Accrued professional services fees 2,586 7,234 Total accrued liabilities $ 54,607 $ 65,497

IMPAIRMENT AND RESTRUCTURING _2

IMPAIRMENT AND RESTRUCTURING CHARGES (Tables)	3 Months Ended
	Mar. 31, 2023
Restructuring and Related Activities [Abstract]
Schedule of Changes in the Restructuring Liabilities	The Company's restructuring and impairment charges are described below (in thousands): Three Months Ended Restructuring charges $ 3,444 Impairment charges 23,164 Total $ 26,608 The following table provides a summary of changes in the restructuring liabilities associated with the Restructuring Plan (in thousands): December 31, Charges Cash Payments March 31, Employee severance $ 394 $ — $ (394) $ — Total $ 394 $ — $ (394) $ —

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Maturities of Operating Lease Liabilities	Contractual obligations under operating lease liabilities were as follows (in thousands): Year Ending December 31: 2023 (remainder of the year) $ 15,609 2024 20,586 2025 20,379 2026 20,131 2027 19,731 Thereafter 34,392 Total lease payments 130,828 Less: imputed interest (34,784) Total lease liabilities $ 96,044

DEBT (Tables)

DEBT (Tables)	3 Months Ended
	Mar. 31, 2023
Debt Disclosure [Abstract]
Schedule of Future Minimum Payments	Contractual obligations for the 2022 term loans comprise principal and interest payments as follows (in thousands): Year Ending December 31, 2023 (remainder of the year) $ 2,141 2024 2,847 2025 15,608 2026 18,623 2027 4,434 Total 43,653 Less: Amount representing interest (8,653) Less: Debt issuance costs (61) Principal payments $ 34,939

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	3 Months Ended
	Mar. 31, 2023
Equity [Abstract]
Schedule of Common Stock Shares Reserved for Future Issuance	The Company had reserved shares of common stock for issuance as follows: March 31, December 31, Options issued and outstanding 311,497 328,193 Unvested restricted stock units and performance-based restricted stock units 2,522,894 2,025,755 Shares available for grant under future stock plans 7,072,322 7,822,637 Shares available for future issuance 9,906,713 10,176,585

EQUITY INCENTIVE PLAN AND STO_2

EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION (Tables)	3 Months Ended
	Mar. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Share-based Awards Available for Grant Under 2016 Plan	Shares Available for Grant Balance as of December 31, 2022 7,822,637 Awards granted (869,619) Awards forfeited 119,304 Balance as of March 31, 2023 7,072,322
Schedule of Restricted Stock Units, Activity	The fair value of market based PRSUs were estimated at the date of grant using the Monte-Carlo option pricing model. A summary is as follows: Restricted Stock Units Performance Based Restricted Stock Units and Market-Based Units Shares Underlying RSUs Weighted Average Grant Date Fair Value Shares Underlying PRSUs 1 Weighted Average Grant Date Fair Value Balance as of December 31, 2022 1,464,666 $ 111.16 561,089 $ 120.22 Granted 611,589 118.84 258,030 137.29 Vested (228,894) 125.73 (24,282) 107.05 Forfeited (55,690) 117.91 (63,614) 119.29 Balance as of March 31, 2023 1,791,671 $ 111.71 731,223 $ 126.76 1 Based on the maximum number of performance based restricted stock units in the key executive grant agreements, the actual number of units granted will be based on the annual unit volume CAGR as described below.
Schedule of Stock Option Activity Under 2006 and 2016 Plans	The following table summarizes stock option activity during the three months ended March 31, 2023: Options Outstanding Options Weighted- Weighted- Aggregate Balance as of December 31, 2022 328,193 $ 43.00 4.43 $ 16,635 Options exercised (16,696) 54.06 Balance as of March 31, 2023 311,497 42.41 4.16 25,425 Options exercisable – March 31, 2023 311,497 $ 42.41 4.16 $ 25,425
Schedule of Total Stock-Based Compensation Expense Included in Statements of Operations and Comprehensive Loss	The following table summarizes the total stock-based compensation expense included in the unaudited condensed consolidated statements of operations for the three months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, 2023 2022 Cost of revenue $ 564 $ 386 Research and development 2,387 1,495 Selling, general and administrative 15,300 12,022 Total stock-based compensation expense $ 18,251 $ 13,903

NET LOSS PER SHARE (Tables)

NET LOSS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2023
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Loss per Share	The following table sets forth the computation of the basic and diluted net loss per share during the three months ended March 31, 2023 and 2022 (in thousands, except per share data): Three Months Ended March 31, 2023 2022 Numerator: Net loss $ (39,109) $ (50,609) Denominator: Weighted-average shares used to compute net loss per common share, basic and diluted 30,297 29,596 Net loss per common share, basic and diluted $ (1.29) $ (1.71)
Schedule of Anti-dilutive Securities Excluded from Diluted Net Loss per Common Share	The following outstanding shares of potentially dilutive securities have been excluded from diluted net loss per common share for the three months ended March 31, 2023 and 2022 because their inclusion would be anti-dilutive (in thousands): Three Months Ended March 31, 2023 2022 Options to purchase common stock 311 481 RSUs and PRSUs unvested 2,523 1,717 Total 2,834 2,198

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2023 performanceObligation systemOption	Mar. 31, 2022	Dec. 31, 2022	Jan. 01, 2023 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of Zio system options | systemOption	3
Number of performance obligations | performanceObligation	2
Federal Government Agencies | Revenue | Customer Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk (as a percent)	24%	22%
Federal Government Agencies | Accounts Receivable | Accounts Receivable Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk (as a percent)	21%		22%
Product And Services Zio X T Service Code93247
Summary Of Significant Accounting Policies [Line Items]
Reimbursement rate				$ 243.65
Product And Services Zio X T Service Code93247 | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated reimbursement rate				247.59
Product And Services Zio X T Service Code93247 | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated reimbursement rate				334.46
Product And Services Zio X T Service Code93243
Summary Of Significant Accounting Policies [Line Items]
Reimbursement rate				231.79
Product And Services Zio X T Service Code93243 | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated reimbursement rate				235.54
Product And Services Zio X T Service Code93243 | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated reimbursement rate				$ 318.17

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Changes in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Change In The Allowance For Doubtful Accounts
Balance, beginning of period	$ 18,475	$ 14,012	$ 14,012
Add: provision for doubtful accounts	5,326	4,413	17,191
Less: write-offs, net of recoveries and other adjustments	(4,726)	(60)	(12,728)
Balance, end of period	$ 19,075	$ 18,365	$ 18,475

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Changes in Contractual Allowance (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Changes In The Contractual Allowance
Balance, beginning of period	$ 41,389	$ 31,274	$ 31,274
Add: provision for contractual adjustments	16,099	9,609	41,158
Less: contractual adjustments	(9,457)	(26)	(31,043)
Balance, end of period	$ 48,031	$ 40,857	$ 41,389

REVENUE - Schedule of Disaggreg

REVENUE - Schedule of Disaggregated Revenue by Payor Type and Major Service (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Revenue, net	$ 111,436	$ 92,378
Contracted third-party payors
Disaggregation of Revenue [Line Items]
Revenue, net	$ 61,907	$ 51,751
Contracted third-party payors | Revenue | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration of credit risk (as a percent)	56%	56%
Centers for Medicare and Medicaid
Disaggregation of Revenue [Line Items]
Revenue, net	$ 26,491	$ 20,062
Centers for Medicare and Medicaid | Revenue | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration of credit risk (as a percent)	24%	22%
Healthcare institutions
Disaggregation of Revenue [Line Items]
Revenue, net	$ 15,781	$ 15,078
Healthcare institutions | Revenue | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration of credit risk (as a percent)	14%	16%
Non-contracted third-party payors
Disaggregation of Revenue [Line Items]
Revenue, net	$ 7,257	$ 5,487
Non-contracted third-party payors | Revenue | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration of credit risk (as a percent)	6%	6%

REVENUE - Narrative (Details)

REVENUE - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenue from Contract with Customer [Abstract]
Contract liability balance, revenue recognized	$ 2.7	$ 2.7

CASH EQUIVALENTS AND SHORT-TE_3

CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Schedule of Cash Equivalents and Available For Sale Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 130,447	$ 158,972
Gains	65	12
Losses	(134)	(409)
Fair Value	130,378	158,575
Cash Equivalents And Available-for-sale Classified As Investments [Abstract]
Cash equivalents	6,845	24,263
Short-term investments	123,533	134,312
Total cash equivalents and short-term investments	130,378	158,575
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	6,845	24,263
Gains	0	0
Losses	0	0
Fair Value	6,845	24,263
U.S. government securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	123,602	134,709
Gains	65	12
Losses	(134)	(409)
Fair Value	$ 123,533	$ 134,312

FAIR VALUE MEASUREMENTS - Narra

FAIR VALUE MEASUREMENTS - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Carrying amount | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Outstanding interest-bearing obligations	$ 34.9	$ 34.9

FAIR VALUE MEASUREMENTS - Sched

FAIR VALUE MEASUREMENTS - Schedule of Fair Value of Company's Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 130,378	$ 158,575
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	6,845	24,263
U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	123,533	134,312
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	6,845	24,263
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	6,845	24,263
Level 1 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	123,533	134,312
Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 2 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	123,533	134,312
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 3 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 0	$ 0

BALANCE SHEET DETAILS -Schedule

BALANCE SHEET DETAILS -Schedule of Components of Inventory and Printed Circuit Board Assemblies ("PCBAs") (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 9,253	$ 9,338
Finished goods	7,135	5,817
Inventory	16,388	15,155
Inventory [Line Items]
Cloud computing arrangements	2,611	2,523
Other	1,284	1,130
Total	25,440	22,252
Printed Circuit Board Assemblies
Inventory [Line Items]
PCBAs	$ 21,500	$ 18,600

BALANCE SHEET DETAILS- Other As

BALANCE SHEET DETAILS- Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
PCBAs	$ 21,545	$ 18,599
Cloud computing arrangements	2,611	2,523
Other	1,284	1,130
Total	$ 25,440	$ 22,252

BALANCE SHEET DETAILS - Narrati

BALANCE SHEET DETAILS - Narrative (Details) - Printed circuit board assemblies - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Inventory [Line Items]
PCBAs	$ 21.5		$ 18.6
Amortization	$ 1.4	$ 1.2

BALANCE SHEET DETAILS - Schedul

BALANCE SHEET DETAILS - Schedule of Components of Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 121,000		$ 110,886
Less: accumulated depreciation and amortization	(38,792)		(35,216)
Total property and equipment, net	82,208		75,670
Depreciation and amortization expense	3,600	$ 3,100
Laboratory and manufacturing equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	4,965		4,911
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	2,448		2,315
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	4,197		4,119
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	23,533		23,144
Internal-use software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	44,877		44,877
Amortization	2,700	$ 2,200
Increase in internal use software	7,900
Internal-use software in development
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	35,919		28,069
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 5,061		$ 3,451

BALANCE SHEET DETAILS - Sched_2

BALANCE SHEET DETAILS - Schedule of Components of Accrued Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued payroll and related expenses	$ 23,696	$ 34,752
Accrued vacation	9,484	8,608
Accrued expenses	8,186	7,006
Claims payable	4,648	4,464
Accrued employee share purchase plan contributions	3,068	1,045
Accrued state and foreign income and sales taxes	2,939	2,388
Accrued professional services fees	2,586	7,234
Total accrued liabilities	54,607	$ 65,497
Transformation expenses	5,700
Increase to accrued payroll and related expenses	2,100
Increase to accrued professional service fees	$ 900

IMPAIRMENT AND RESTRUCTURING _3

IMPAIRMENT AND RESTRUCTURING CHARGES - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Feb. 28, 2022	Mar. 31, 2023	Mar. 31, 2022
Restructuring Cost and Reserve [Line Items]
Impairment and restructuring charges		$ 0	$ 26,608
Restructuring charges			3,444
Reduction to leased square footage (percent)	50%
Impairment charges to leasehold improvements, furniture and fixtures		0	23,164
2022 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Employee severance | 2022 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 0	$ 3,400

IMPAIRMENT AND RESTRUCTURING _4

IMPAIRMENT AND RESTRUCTURING CHARGES - Restructuring and Impairment Charges (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Restructuring and Related Activities [Abstract]
Restructuring charges		$ 3,444
Impairment charges	$ 0	23,164
Total	$ 0	$ 26,608

IMPAIRMENT AND RESTRUCTURING _5

IMPAIRMENT AND RESTRUCTURING CHARGES - Summary of Changes in Restructuring Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Restructuring Reserve [Roll Forward]
Charges		$ 3,444
2022 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 394
Charges	0
Cash Payments	(394)
Restructuring reserve, ending balance	0
Employee severance | 2022 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	394
Charges	0	$ 3,400
Cash Payments	(394)
Restructuring reserve, ending balance	$ 0

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) Milestone	May 04, 2023 USD ($)	Dec. 31, 2019 USD ($)	Sep. 03, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Collaboration agreement, additional milestone payments, between 2022 and early 2023	$ 1,750
Collaboration agreement, milestones achieved | Milestone	0
Subsequent Event
Lessee, Lease, Description [Line Items]
Collaboration agreement milestone payments		$ 11,000
Verily Life Sciences LLC
Lessee, Lease, Description [Line Items]
Upfront fee related to development agreement			$ 5,000
Additional aggregate milestone payments related to development agreement				$ 12,750

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Leases (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2023 (remainder of the year)	$ 15,609
2024	20,586
2025	20,379
2026	20,131
2027	19,731
Thereafter	34,392
Total lease payments	130,828
Less: imputed interest	(34,784)
Total lease liabilities	$ 96,044

DEBT - Narrative (Details)

DEBT - Narrative (Details)		1 Months Ended	3 Months Ended
	Mar. 28, 2022 USD ($) payment_installment	Oct. 31, 2018 USD ($)	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)
Debt Instrument [Line Items]
Proceeds from issuance of debt			$ 0	$ 35,000,000
Debt issuance costs, net			1,800,000
Letters of credit			8,400,000
2022 Term Loan
Debt Instrument [Line Items]
Debt instrument, covenant compliance, amount	$ 15,000,000
2022 Term Loan | Minimum
Debt Instrument [Line Items]
Debt instrument, covenant, quick ratio	100%
2022 Term Loan | Maximum
Debt Instrument [Line Items]
Debt instrument, covenant, quick ratio	115%
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 25,000,000
Letter of Credit | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	15,000,000
Cash Management Services | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 15,000,000
Third Amended and Restated SVB Loan Agreement
Debt Instrument [Line Items]
Debt issuance costs, net			61,000
Third Amended and Restated SVB Loan Agreement | SVB Term Loan
Debt Instrument [Line Items]
Proceeds from issuance of debt		$ 35,000,000
Amount outstanding under revolving credit line				$ 18,500,000
Commitment fee percentage	5%
Third Amended and Restated SVB Loan Agreement | SVB Term Loan | Minimum
Debt Instrument [Line Items]
Commitment fee percentage	1%
Third Amended and Restated SVB Loan Agreement | SVB Term Loan | Maximum
Debt Instrument [Line Items]
Commitment fee percentage	3%
Third Amended and Restated SVB Loan Agreement | SVB Term Loan | Prime rate
Debt Instrument [Line Items]
Stated interest rate (in percentage)	3.50%
Third Amended and Restated SVB Loan Agreement | SVB Term Loan | 2022 Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 75,000,000
Proceeds from line of credit	35,000,000
Line of credit facility, remaining borrowing capacity	40,000,000
Term loan borrowed installments	$ 10,000,000
Repayment consecutive monthly installments | payment_installment	24
Third Amended and Restated SVB Loan Agreement | SVB Term Loan | 2022 Term Loan | Prime rate
Debt Instrument [Line Items]
Interest rate spread (as a percent)	0.25%
Third Amended and Restated SVB Loan Agreement | SVB Term Loan | 2018 Term Loan
Debt Instrument [Line Items]
Repayment of long-term line of credit	$ 18,500,000
Third Amended and Restated SVB Loan Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Amount outstanding under revolving credit line			$ 0
Commitment fee percentage	0.15%
Third Amended and Restated SVB Loan Agreement | Revolving Credit Facility | Prime rate
Debt Instrument [Line Items]
Stated interest rate (in percentage)	3.50%
Third Amended and Restated SVB Loan Agreement | Revolving Credit Facility | 2022 Term Loan | Prime rate
Debt Instrument [Line Items]
Interest rate spread (as a percent)	0.25%

DEBT - Schedule of Future Minim

DEBT - Schedule of Future Minimum Payments (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Debt Instrument [Line Items]
Less: Debt issuance costs	$ (1,800)
Third Amended and Restated SVB Loan Agreement
Debt Instrument [Line Items]
2023 (remainder of the year)	2,141
2024	2,847
2025	15,608
2026	18,623
2027	4,434
Total	43,653
Less: Amount representing interest	(8,653)
Less: Debt issuance costs	(61)
Principal payments	$ 34,939

INCOME TAXES (Details)

INCOME TAXES (Details)	Mar. 31, 2023 USD ($)
Income Tax Disclosure [Abstract]
Benefit recognized for net operating loss carryforwards	$ 0

STOCKHOLDERS' EQUITY - Narrativ

STOCKHOLDERS' EQUITY - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Equity [Abstract]
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, par value (in USD per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, par value (in USD per share)	$ 0.001	$ 0.001
Dividends declared	$ 0

STOCKHOLDERS' EQUITY - Schedule

STOCKHOLDERS' EQUITY - Schedule of Common Stock Shares Reserved for Future Issuance (Details) - shares	Mar. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Shares available for future issuance (in shares)	9,906,713	10,176,585
Options issued and outstanding
Class of Stock [Line Items]
Shares available for future issuance (in shares)	311,497	328,193
Unvested restricted stock units and performance-based restricted stock units
Class of Stock [Line Items]
Shares available for future issuance (in shares)	2,522,894	2,025,755
Shares available for grant under future stock plans
Class of Stock [Line Items]
Shares available for future issuance (in shares)	7,072,322	7,822,637

EQUITY INCENTIVE PLAN AND STO_3

EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION - Summary of Share-based Awards Available for Grant under 2016 Plan (Details) - 2016 Plan	3 Months Ended
	Mar. 31, 2023 shares
Share-Based Awards Available For Grant
Beginning balance (in shares)	7,822,637
Awards granted (in shares)	(869,619)
Awards forfeited (in shares)	119,304
Ending balance (in shares)	7,072,322

EQUITY INCENTIVE PLAN AND STO_4

EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION - Restricted Stock Units ("RSU") and Performance-Based Restricted Stock Units ("PRSU") Activity (Details)	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Restricted Stock Units
Shares Underlying RSUs
Beginning balance (in shares) | shares	1,464,666
Granted (in shares) | shares	611,589
Vested (in shares) | shares	(228,894)
Forfeited (in shares) | shares	(55,690)
Ending balance (in shares) | shares	1,791,671
Weighted Average Grant Date Fair Value
Beginning balance (in USD per share) | $ / shares	$ 111.16
Granted (in USD per share) | $ / shares	118.84
Vested (in USD per share) | $ / shares	125.73
Forfeited (in USD per share) | $ / shares	117.91
Ending balance (in USD per share) | $ / shares	$ 111.71
Performance Based Restricted Stock Units and Market-Based Units
Shares Underlying RSUs
Beginning balance (in shares) | shares	561,089
Granted (in shares) | shares	258,030
Vested (in shares) | shares	(24,282)
Forfeited (in shares) | shares	(63,614)
Ending balance (in shares) | shares	731,223
Weighted Average Grant Date Fair Value
Beginning balance (in USD per share) | $ / shares	$ 120.22
Granted (in USD per share) | $ / shares	137.29
Vested (in USD per share) | $ / shares	107.05
Forfeited (in USD per share) | $ / shares	119.29
Ending balance (in USD per share) | $ / shares	$ 126.76

EQUITY INCENTIVE PLAN AND STO_5

EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	39 Months Ended
	Feb. 28, 2023	Mar. 31, 2023	Mar. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted in period (shares)			0
Unvested restricted stock units and performance-based restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unamortized compensation costs, net of estimated forfeitures related to restricted stock unit and performance share		$ 157.2	$ 157.2
Unamortized compensation costs related to unvested stock options, expected period of recognition (in years)		2 years
Intrinsic value of equity other than options nonvested		$ 222.2	222.2
Performance Based Restricted Stock Units ("PRSU")
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unamortized compensation costs, net of estimated forfeitures related to restricted stock unit and performance share		$ 43.1	43.1
Unamortized compensation costs related to unvested stock options, expected period of recognition (in years)		2 years 4 months 24 days
Intrinsic value of equity other than options nonvested		$ 90.7	$ 90.7
Expected term (in years)	2 years 10 months 24 days
Risk-free interest rate	4.50%
Expected volatility	83.80%
Dividend yield	0%
Performance Based Restricted Stock Units ("PRSU") | 2023 Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance threshold (in percentage)	15%
Performance Based Restricted Stock Units ("PRSU") | 2023 Awards | Minimum | Awarded February 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance target to be earned at performance threshold (in percentage)	50%
Performance Based Restricted Stock Units ("PRSU") | 2023 Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance threshold (in percentage)	25%
Performance Based Restricted Stock Units ("PRSU") | 2023 Awards | Maximum | Awarded February 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance target to be earned at performance threshold (in percentage)	200%

EQUITY INCENTIVE PLAN AND STO_6

EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Options Outstanding
Beginning balance (in shares)	328,193
Options exercised (in shares)	(16,696)
Ending balance (in shares)	311,497	328,193
Options exercisable (in shares)	311,497
Weighted- Average Exercise Price Per Share
Beginning balance (in USD per share)	$ 43
Options exercised (in USD per share)	54.06
Ending balance (in USD per share)	42.41	$ 43
Options exercisable (in USD per share)	$ 42.41
Weighted- Average Remaining Contractual Life (years)
Weighted-average remaining contractual life for options outstanding (in years)	4 years 1 month 28 days	4 years 5 months 4 days
Weighted-average remaining contractual life for options exercisable (in years)	4 years 1 month 28 days
Aggregate Intrinsic Value (in thousands)
Aggregate intrinsic value of options outstanding	$ 25,425	$ 16,635
Aggregate intrinsic value of options exercisable	$ 25,425

EQUITY INCENTIVE PLAN AND STO_7

EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION - Employee Stock Purchase Plan (Details) $ in Millions	1 Months Ended	3 Months Ended
	Oct. 31, 2016 purchase_period	Mar. 31, 2023 USD ($) shares	Dec. 31, 2022 shares
Subsidiary, Sale of Stock [Line Items]
Shares available for future issuance (in shares)		9,906,713	10,176,585
ESPP
Subsidiary, Sale of Stock [Line Items]
Common stock issued to employees (in shares)		0
Employee Stock Purchase Plan
Subsidiary, Sale of Stock [Line Items]
Percentage of payroll deductions of eligible compensation	15%
Percentage of common stock fair market value available for employee purchase	85%
Shares available for future issuance (in shares)		2,206,279
Total unamortized compensation costs, net of estimated forfeitures related to unvested stock options | $		$ 3.4
Unamortized compensation costs related to unvested stock options, expected period of recognition (in years)		2 months 12 days
Employee Stock Purchase Plan | ESPP
Subsidiary, Sale of Stock [Line Items]
Offering period (in months)	12 months
Number of purchase period | purchase_period	2
Purchase period (in months)	6 months

EQUITY INCENTIVE PLAN AND STO_8

EQUITY INCENTIVE PLAN AND STOCK-BASED COMPENSATION (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 18,251	$ 13,903
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	564	386
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	2,387	1,495
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 15,300	$ 12,022

NET LOSS PER SHARE - Computatio

NET LOSS PER SHARE - Computation of Basic and Diluted Net Loss per Share Attributable to Common Stock holders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Numerator:
Net loss	$ (39,109)	$ (50,609)
Denominator:
Weighted-average shares used to compute net loss per common share, basic (in shares)	30,297,000	29,596,000
Weighted-average shares used to compute net loss per common share, diluted (in shares)	30,297,000	29,596,000
Net loss per common share, basic (in USD per share)	$ (1.29)	$ (1.71)
Net loss per common share, diluted (in USD per share)	$ (1.29)	$ (1.71)

NET LOSS PER SHARE - Schedule o

NET LOSS PER SHARE - Schedule of Anti-dilutive Securities Excluded from Diluted Net Loss per Common Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss (in shares)	2,834	2,198
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss (in shares)	311	481
RSUs and PRSUs unvested
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss (in shares)	2,523	1,717