Natera (NTRA) 10-K 24 Mar 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2015	Feb. 29, 2016	Jun. 30, 2015
Document and Entity Information
Entity Registrant Name	Natera, Inc.
Entity Central Index Key	1,604,821
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$ 0.6
Entity Common Stock, Shares Outstanding		50,852,374
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 28,947	$ 87,176
Restricted cash, current portion	901	503
Short-term investments	201,586
Accounts receivable, net of allowance of $971 in 2015 and $527 in 2014	5,862	5,942
Inventory	8,093	11,542
Prepaid expenses and other current assets	5,337	1,314
Total current assets	250,726	106,477
Property and equipment, net	12,710	14,574
Restricted cash, long term portion	683	808
Other assets	1,121	1,764
Total assets	265,240	123,623
Current liabilities:
Accounts payable	7,332	8,867
Accrued compensation	8,552	5,980
Other accrued liabilities	18,708	10,341
Deferred revenue	144	112
Equipment loan, current portion		2,340
Short-term debt financing	42,090
Warrants	3,649	2,232
Total current liabilities	80,475	29,872
Equipment loan, long term portion		3,510
Senior secured term loan		20,964
Total long-term liabilities		24,474
Total liabilities	$ 80,475	$ 54,346
Commitments and contingencies (Note 6)
Convertible preferred stock issuable in series, $0.0001 par value: 50,000 and 51,233 shares authorized at December 31, 2015 and December 31, 2014, respectively, 0 and 31,397 shares issued and outstanding at December 31, 2015 and December 31, 2014, respectively; aggregate liquidation preference of $133,757 as of December 31, 2014		$ 240,612
Stockholders’ deficit:
Preferred stock, $0.0001 par value: 50,000 shares authorized; no shares issued and outstanding at December 31, 2015 and 2014, respectively
Common stock, $0.0001 par value: 750,000 and 82,000 shares authorized at December 31, 2015 and December 31, 2014, respectively, 50,346 and 6,879 shares issued and outstanding at December 31, 2015 and December 31, 2014, respectively	$ 5	$ 1
Additional paid in capital	436,259	8,664
Notes receivable from officers		(192)
Accumulated deficit	(250,083)	(179,808)
Accumulated other comprehensive loss	(1,416)
Total stockholders’ equity (deficit)	184,765	(171,335)
Total liabilities, convertible preferred stock, and stockholders’ equity	$ 265,240	$ 123,623

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Consolidated Balance Sheets
Allowances on accounts receivable	$ 971	$ 527
Convertible preferred stock, par value (in dollars per share)		$ 0.0001
Convertible preferred stock, shares authorized		51,233,000
Convertible preferred stock, shares issued		31,397,000
Convertible preferred stock, shares outstanding		31,397,000
Convertible preferred stock, liquidation preference (in dollars)		$ 133,757
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	750,000,000	82,000,000
Common stock, shares issued	50,346,000	6,879,000
Common stock, shares outstanding	50,346,000	6,879,000

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Product revenues	$ 188,168	$ 157,308	$ 54,955
Other revenues	2,187	1,981	216
Total revenues	190,355	159,289	55,171
Cost and expenses
Cost of product revenues	112,845	78,396	37,275
Research and development	27,711	17,292	11,550
Selling, general and administrative	109,637	62,936	31,614
Total cost and expenses	250,193	158,624	80,439
Gain (loss) from operations	(59,838)	665	(25,268)
Interest Expense	(3,505)	(4,219)	(1,873)
Interest expense from accretion of convertible notes			(7,901)
Interest benefit (expense) from changes in the fair value of long term debt	964	118	(2,166)
Other (expense) income, net	(7,896)	(1,716)	98
Net (loss)	(70,275)	(5,152)	(37,110)
Unrealized loss on available-for-sale securities, net of tax	(1,416)
Comprehensive (loss)	$ (71,691)	$ (5,152)	$ (37,110)
Basic and diluted net loss per share (in dollars per share)	$ (2.68)	$ (1.07)	$ (9.66)
Weighted-average number of shares used in computing basic and diluted net loss per share:	26,204	4,800	3,841

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit) - USD ($) shares in Thousands	Preferred StockConvertible preferred stock	Preferred StockC and D	Preferred StockE	Preferred StockF	Common stock	Additional Paid-in Capital	Notes Receivable from Officers	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Convertible preferred stock	E	F	Total
Balance at Dec. 31, 2012	$ 10,516,000				$ 1,000	$ 1,422,000	$ (192,000)		$ (137,546,000)				$ (136,315,000)
Balance (in shares) at Dec. 31, 2012					5,849
Convertible Preferred Stock Balance (in shares) at Dec. 31, 2012	11,572
Issuance of convertible preferred stock		$ 139,664,000	$ 35,019,000
Issuance of convertible preferred stock (in shares)		9,592	5,884
Issuance of common stock upon exercise of stock options	$ 0				$ 0	259,000	0	$ 0	0				259,000
Issuance of common stock upon exercise of stock options (in shares)	0				712
Stock based compensation						1,657,000							1,657,000
Issuance costs of Series F Preferred Stock											$ (405,371)
Net loss									(37,110,000)				(37,110,000)
Balance at Dec. 31, 2013	$ 185,199,000				$ 1,000	3,338,000	(192,000)		(174,656,000)				(171,509,000)
Balance (in shares) at Dec. 31, 2013					6,561
Convertible preferred stock balance (in shares) at Dec. 31, 2013	27,048
Issuance of convertible preferred stock				$ 55,413,000
Issuance of convertible preferred stock (in shares)				4,349
Issuance of common stock upon exercise of stock options	$ 0				$ 0	169,000	0	0	0				169,000
Issuance of common stock upon exercise of stock options (in shares)	0				318
Stock based compensation						5,157,000							5,157,000
Issuance costs of Series F Preferred Stock												$ (86,933)
Net loss									(5,152,000)				(5,152,000)
Balance at Dec. 31, 2014	$ 240,612,000				$ 1,000	8,664,000	(192,000)		(179,808,000)				$ (171,335,000)
Balance (in shares) at Dec. 31, 2014					6,879								6,879
Convertible preferred stock balance at Dec. 31, 2014										$ 240,612,000	$ 35,019,000	$ 55,413,000	$ 240,612,000
Convertible preferred stock balance (in shares) at Dec. 31, 2014	31,397												31,397
Issuance of common stock upon exercise of stock options						1,258,000							$ 1,258,000
Issuance of common stock upon exercise of stock options (in shares)					1,170
Stock based compensation						7,326,000							7,326,000
Issuance costs of Series F Preferred Stock				$ (27,000)
Officer loan receivable repayment							$ 192,000						192,000
Issuance of common stock in connection with the initial public offering					$ 1,000	182,465,000							182,466,000
Issuance of common stock in connection with the initial public offering (in shares)					10,900
Issuance costs of Initial Public Offering						(4,036,000)							(4,036,000)
Conversion of all Preferred Stock into Common Stock upon the completion of the initial public offering	$ (240,585,000)				$ 3,000	240,582,000							240,585,000
Conversion of all Preferred Stock into Common Stock upon the completion of the initial public offering (in shares)	(31,397)				31,397
Net loss									(70,275,000)				(70,275,000)
Accumulated other comprehensive income (loss)								(1,416,000)					(1,416,000)
Balance at Dec. 31, 2015					$ 5,000	$ 436,259,000		$ (1,416,000)	$ (250,083,000)				$ 184,765,000
Balance (in shares) at Dec. 31, 2015					50,346								50,346

Consolidated Statements of Con6

Consolidated Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit) (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
E
Preferred stock (in dollars per share)	$ 6.0199	$ 6.02
Preferred stock issuance costs		$ 405,371
F
Preferred stock (in dollars per share)	$ 12.7629
Preferred stock issuance costs	$ 86,933

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Activities
Net loss	$ (70,275)	$ (5,152)	$ (37,110)
Adjustments to reconcile net loss to net cash used in operating activities:
Accretion of convertible notes			7,901
Non-cash interest			15
Depreciation and amortization	5,535	5,148	2,528
Amortization of debt discount	28
Amortization of premium on investment securities	288
Loss (gain) on sales of property and equipment	(2)	11
Impairment of assets	1,557
Stock based compensation	7,326	5,157	1,657
(Gain)/loss from changes in fair value of warrants	1,481	1,664	(52)
(Gain)/loss from change in fair value of long term debt	(964)	(118)	2,166
Provision for doubtful accounts	529	349	527
Loss on debt extinguishment	7,313
Changes in operating assets and liabilities
Accounts receivable	(450)	341	(5,848)
Inventory	2,929	(890)	(9,054)
Prepaid expenses and other current assets	(3,797)	(137)	(820)
Restricted cash	(273)
Other assets	(1,041)	(24)	(63)
Accounts payable	1,354	(2,430)	6,792
Income taxes payable		(15)
Accrued compensation	2,572	2,994	1,658
Other accrued liabilities	8,026	4,450	4,702
Deferred revenue	32	(858)	869
Net cash (used in) provided by operating activities	(37,832)	10,490	(24,132)
Investing Activities
Purchases of investments	(203,290)
Proceeds from sale of property and equipment	463	15
Purchases of property and equipment, net	(7,852)	(9,957)	(8,245)
Net cash (used in) investing activities	(210,679)	(9,942)	(8,245)
Financing Activities
Proceeds from issuance of common stock, net of issuance costs	180,001	170	259
Proceeds from exercise of stock options	1,258
Bridge loan			2,000
Proceeds from issuance of preferred stock, net		55,413	33,019
Proceeds from senior secured term loan			20,000
Costs paid for loan	(6)		(479)
Proceeds from short-term financing	42,000
Proceeds from equipment financing		5,105	3,700
Repayments of equipment financing	(5,850)	(2,480)	(475)
Repayments of secured financings	(20,000)
Proceeds from collection of officer receivable	192
Payment to lender for debt extinguishment	(7,313)
Change in restricted cash		(415)	(881)
Deferred offering costs		(1,661)	(17)
Net cash provided by financing activities	190,282	56,132	57,126
Net (decrease) increase in cash	(58,229)	56,680	24,749
Cash at beginning of period	87,176	30,496	5,747
Cash at end of period	28,947	87,176	30,496
Supplemental disclosure of cash flow information:
Cash paid for interest	2,060	2,063	920
Purchases of property and equipment through accounts payable and accruals	765	$ 3,223	2,942
Non cash property and equipment purchase	2
Conversion of convertible preferred stock to common stock	$ 240,585
C and D
Supplemental disclosure of cash flow information:
Conversion of Debt			139,664
Bridge loan
Supplemental disclosure of cash flow information:
Conversion of Debt			$ 2,002

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2015
Description of Business
Description of Business	1. Description of Business Natera, Inc. (the "Company") was formed in the state of California as Gene Security Network, LLC in November 2003 and incorporated in the state of Delaware in January 2007. The Company’s mission is to change the management of genetic disease worldwide. The Company operates a laboratory certified under the Clinical Laboratory Improvement Amendments ("CLIA") providing a host of preconception and prenatal genetic testing services. The Company operates in one segment and has a subsidiary that operates in the state of Texas. The Company's product offerings include its Panorama Non-Invasive Prenatal Test ("NIPT") that screens for chromosomal abnormalities of a fetus typically with a blood draw from the mother; Horizon Carrier Screening ("Horizon") to determine carrier status for a large number of severe genetic diseases that could be passed on to the carrier’s children; Spectrum Pre-implantation Genetic Screening ("PGS") and Spectrum Pre-implantation Genetic Diagnosis ("PGD") to analyze chromosomal anomalies or inherited genetic conditions during an in vitro fertilization ("IVF") cycle to select embryos with the highest probability of becoming healthy children; Anora Products of Conception ("POC") test to rapidly and extensively analyze fetal chromosomes to understand the cause of miscarriage; Non-Invasive Paternity Testing ("PAT"), to determine paternity by analyzing the fragments of fetal deoxyribonucleic acid ("DNA") in a pregnant mother's blood and a blood sample from the alleged father(s), which is marketed and sold exclusively by a licensee from whom the Company receives a royalty. All testing is available principally in the United States and Europe. The Company also offers Constellation, a cloud-based software product that allows laboratory customers to gain access through the cloud to the Company’s algorithms and bioinformatics in order to validate and launch tests based on the Company’s technology. Reverse Stock Split The Company's board of directors and stockholders approved a 1-for- 1.63 reverse split of its capital stock, which was effected on June 19, 2015. All references to common stock, options to purchase common stock, restricted stock, share data, per share data, warrants, convertible preferred stock and related information have been retroactively adjusted where applicable in this report to reflect the reverse stock split of the Company's capital stock as if it had occurred at the beginning of the earliest period presented. Initial Public Offering In July 2015, the Company completed an initial public offering (“IPO”), and subsequently in August 2015, the Company completed the sale of additional shares upon exercise of the underwriters’ over-allotment option. In connection with the IPO, including the over-allotment option, the Company sold 10,900,000 shares of common stock at $ 18.00 per share, which raised $ 178.5 million in proceeds, net of underwriting discounts and commissions and offering expenses.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2 . Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”). . Need to Raise Additional Capital The Company has incurred net losses since its inception and anticipates net losses and negative operating cash flows for the near future. For the year ended December 31, 2015, the Company had a net loss of $ 70.3 million, and as of December 31, 2015, it had an accumulated deficit of $ 250.1 million . At December 31, 2015, the Company had $ 28.9 million in cash and cash equivalents and $201.6 million in marketable securities. While the Company has introduced multiple products that are generating revenues, these revenues have not been sufficient to fund all operations. Accordingly, the Company has funded the portion of operating costs that exceeds revenues through a combination of equity issuances, debt issuances, and other financings. The Company expects to develop and commercialize future products and, consequently, it will need to generate additional revenues to achieve future profitability and may need to raise additional equity or debt financing that may not be available, if at all, at terms acceptable to the Company to fund future operations. Based on our current business plan, we believe that our existing cash and marketable securities will be sufficient to meet our anticipated cash requirements for the next 12 months. Principles of Consolidation The accompanying condensed consolidated financial statements include all the accounts of the Company and its subsidiary. The Company established a subsidiary that operates in the state of Texas in December 2014 to support the Company’s laboratory and operational functions, which became active in the second quarter of 2015. All intercompany balances and transactions have been eliminated. Use of Estimates The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions about future events that affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Significant items subject to such estimates include the allowance for doubtful accounts, accrued liability for potential refund requests, stock-based compensation, the fair value of common stock and fair value of debt accounted for under ASC 815, as well as income tax uncertainties. These estimates and assumptions are based on management's best estimates and judgment. Management regularly evaluates its estimates and assumptions using historical experience and other factors; however, actual results could differ from these estimates and could have an adverse effect on the Company's financial statements. Fair Value The Company discloses the fair value of financial instruments for financial assets and liabilities for which the value is practicable to estimate. Fair value is defined as the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The Company carried senior secured term loan and warrants at fair value according to the fair value measurement guidance. Cash and Cash Equivalents Cash and cash equivalents consist of cash and money market deposits with financial institutions. Restricted Cash The Company discloses both short-term and long-term restricted cash. Short-term restricted cash consists of $0.8 million, securing our letter of credit for our headquarters operating lease which expires in October 2016 and $0.1 million in payments received by certain customers. Long-term restricted cash consists of $0.4 million deposit per credit card terms and $0.3 million securing our letter of credit for our headquarters operating lease which expires in January 2017. Investments Management determines the appropriate classification of securities at the time of purchase and reevaluates such determination at each balance sheet date. The Company generally classifies its entire investment portfolio as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company classifies all investments as short-term, even though the stated maturity may be more than one year from the current balance sheet date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity (deficit). Risk and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash, accounts receivable and investments. The Company limits its exposure to credit loss by placing its cash in financial institutions with high credit ratings. The Company's cash may consist of deposits held with banks that may at times exceed federally insured limits. The Company performs evaluations of the relative credit standing of these financial institutions and limits the amount of credit exposure with any one institution. The Company bills third-party payers for certain tests performed. The amount that is ultimately received from the payer for our claim and the timing of such payments are subject to the determination of the payer based on the nature of the test performed and their view of our business practices with respect to collections of plan deductibles and co-payments from patients and other activities. This determination can impact both the amount and timing of when our invoices are collected. Payers may also withhold payments and request refunds of prior payments if we do not perform in accordance with the policies of these payers. The Company performs evaluations of financial conditions for clinics and laboratory partners and generally does not require collateral to support credit sales. For 2015 and 2014, there were no customers exceeding 10% in total revenue. For 2013, two customers accounted for more than 10% of our revenues: Quest Diagnostics Incorporated ( 16% ) and Progenity, Inc. ( 12% ) . As of December 31, 2015 and 2014, no customers had a receivable balance greater than 10% of net accounts receivable, and as of December 31, 2013, two customers had receivable balances of 37% a nd 18% of total accounts receivable . Allowance for Doubtful Accounts Trade accounts receivable are recorded at the amount billed to the laboratory partners and clinics. Reducing this amount is an allowance for doubtful accounts for estimated losses resulting from the inability of its customers to make the contracted payments. Management analyzes accounts receivable and historical bad debt experience, customer creditworthiness, current economic trends, and changes in customer payment history when evaluating the adequacy of the allowance for doubtful accounts. Accounts receivable are written off against the allowance when there is substantive evidence that the account will not be paid. Revenue Recognition The Company generally bills an insurance carrier, a clinic or a patient for the test upon delivery of the test result. The Company also bills patients directly for out-of-pocket costs not covered by their insurance carriers representing co-pays and deductibles in accordance with their insurance carrier and health plans. The Company may not get reimbursed for tests completed if the tests are not covered under the insurance carrier’s reimbursement policies or the Company is not a qualified provider to the insurance carrier. For tests performed, where an agreed upon reimbursement rate or fixed fee and a predictable history or likelihood of collections exists, the Company recognizes revenues upon delivery of the test report to the prescribing physician based on the established billing rate less contractual and other adjustments, such as an allowance for doubtful accounts, to arrive at the amount that the Company expects to collect. In all other situations, as the Company does not have a sufficient history of collection and is not able to determine collectability, the Company recognizes revenues when cash is received. From time to time, we receive requests for refunds of payments previously made by insurance carriers. The Company has established an accrued liability for potential refund requests based on our experience. In cases where the Company sells its tests through its laboratory partners, the majority of the laboratory partners bill the patient, clinic, or insurance carrier for the performance of the Company's tests. For tests sold through a limited number of its laboratory partners, the Company bills directly to a patient, clinic or insurance carrier, or a combination of the insurance carrier and patient for the fees. The Company considers its services rendered when it delivers reports of its test results to the laboratory partner, clinic or patient. When the Company has contracted fixed rates for its services and collectability of its revenues is reasonably assured, it recognizes revenues upon delivery of test reports. The fixed fees identified in contracts with laboratory partners change only if a pricing amendment is agreed upon between both parties. For cases in which there is no fixed price established with a laboratory partner, the Company then recognizes revenues from partner distributed tests on a cash basis. Certain of the Company's arrangements include multiple deliverables. For revenue arrangements with multiple deliverables, the Company evaluates each deliverable to determine whether it qualifies as a separate unit of accounting. This determination is based on whether the deliverable has "stand-alone value" to the customer and whether a general right of return exists. The consideration that is fixed or determinable is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. The consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. The Company uses judgment in identifying the deliverables in its arrangements, assessing whether each deliverable is a separate unit of accounting, and in determining the best estimate of selling price for certain deliverables. The Company also uses judgment in determining the period over which the deliverables are recognized in certain of its arrangements. Any amounts received that do not meet the criteria for revenue recognition are recorded as deferred revenue until such criteria are met. The Company receives royalty revenue through the licensing and the provisioning of services to support the use of the Company's proprietary technology with its customer. Royalty revenues are recognized when earned under the terms of the related agreements and are included in Other Revenues in the statements of operations. The Company recognizes revenue from the cloud-based distribution service offering. The Company grants customers licenses to use the Company’s proprietary intellectual properties and the cloud-based Natera software, and provides the other services to support the use of the Company's proprietary technology with its customers. Natera’s proprietary software is used in connection with the analysis of DNA sequence data in a manner yielding a result indicating the likely presence or absence of full or partial chromosomal abnormalities. The licensees do not have the right to possess Natera software, but rather are treated as software as a service. The revenues are recognized on an accrual basis (assuming all revenue recognition criteria are met) under the terms of the related agreements and are included in other revenues in the statements of operation. Cost of Product Revenues Cost of product revenues includes the cost of materials, direct labor of laboratory personnel, equipment and infrastructure expenses associated with processing blood and other samples, quality control analyses, and shipping charges to transport samples and specimens from ordering physicians, clinics or individuals. Infrastructure expenses include allocated facility and related occupancy costs. Costs associated with the performance of diagnostic services are recorded as tests are processed. Costs associated with grants received are reported in research and development expenses. Research and Development The Company records research and development costs in the period incurred. Research and development costs consist of personnel costs, contract services, cost of materials utilized in performing tests, costs of clinical trials and allocated facilities and related overhead expenses. Advertising Costs The Company expenses advertising costs as incurred. The Company incurred advertising costs of $1.1 million, $1.1 million and $0.4 million during 2015, 2014 and 2013, respectively. Product Shipment Costs The Company expenses product shipment costs in cost of product revenues in the accompanying statements of operations. Shipping and handling costs for the years ended December 31, 2015, 2014 and 2013 were $7.0 million, $4.5 million and $2.0 million, respectively. Income Taxes Income taxes are recorded in accordance with Financial Accounting Standards Board ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Tax benefits are recognized when it is more likely than not that a tax position will be sustained during an audit. Deferred tax assets are reduced by a valuation allowance if current evidence indicates that it is considered more likely than not that these benefits will not be realized. Stock ‑Based Compensation Stock ‑based compensation related to stock options granted to the Company’s employees is measured at the grant date based on the fair value of the award. The fair value is recognized as expense over the requisite service period, which is generally the vesting period of the respective awards. No compensation cost is recognized on stock options for employees who do not render the requisite service and therefore forfeit their rights to the stock options. The Company uses the Black ‑Scholes option ‑pricing model to estimate the fair value of its stock options. The Company accounts for stock options issued to non-employees based on the estimated fair value of the awards using the Black-Scholes option-pricing model. The measurement of stock-based compensation is subject to periodic adjustments as the underlying equity instruments vest, and the resulting change in value, if any, is recognized in the Company's statements of operations during the period that the related services are rendered. The Black-Scholes option-pricing model requires the input of the Company's expected stock price volatility, the expected life of the awards, a risk-free interest rate, and expected dividends. Determining these assumptions requires significant judgment. The expected term was based on the simplified method and where the Company did not qualify to use the simplified method, the Company used the lattice model, and the volatility rate was based on that of publicly traded companies in the DNA sequencing, diagnostics, or personalized medicine industries. When selecting the public companies in these industries to be used in the volatility calculation, companies were selected with comparable characteristics to the Company, including enterprise value and financial leverage. Companies were also selected with historical share price volatility sufficient to meet the expected life of the Company's stock options. The historical volatility data was computed using the daily closing prices for the selected companies' shares during the equivalent period of the calculated expected term of the Company's stock options. The expected life of the non-employee option grants was based on their remaining contractual life at the measurement date. The risk-free interest rate assumption was based on U.S. Treasury instruments with maturities that were consistent with the option's expected life. The expected dividend assumption was based on the Company's history and expectation of dividend payouts. Warrants The Company accounts for warrants to purchase shares of its common stock as a liability at fair value on the balance sheet date because the Company may be obligated to redeem these warrants at some point in the future. The warrants are subject to remeasurement at each balance sheet date, with changes in fair value recognized as a gain or loss from the changes in fair value of the warrants in the statements of operations. The Company will continue to adjust the liability for changes in fair value until such time that the warrants are converted or expire. Capitalized Software Held for Internal Use We capitalize costs of software held for internal use during the application development stage of a project and amortize those costs over their estimated useful lives of three years. The net book value of capitalized software held for internal use was $0.8 million and $0 as of December 31, 2015 and 2014, respectively. Amortized expense for amounts previously capitalized for the year ended December 31, 2015 was $0.2 million. Accumulated Other Comprehensive Loss Comprehensive loss and its components encompass all changes in equity other than those with stockholders, and include net loss, unrealized gains and losses on available-for-sale marketable securities. As of December 31, 2015 and 2014, accumulated other comprehensive loss consisted of $1.4 million and nil of unrealized losses on available-for-sale marketable securities. There were no reclassifications out of accumulated other comprehensive loss during years ended December 31, 2015 and 2014 . Property and Equipment Property and equipment, including purchased and internally developed software, are stated at cost. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, which are generally three years. Leasehold improvements are amortized using the straight-line method over the estimated useful lives of the assets or the remaining term of the lease, whichever is shorter. The Company periodically reviews the depreciable lives assigned to property and equipment placed in service and change the estimates of useful lives to reflect the results of such reviews. During April 2015, the Company increased the depreciable lives of certain sequencing and automation machinery equipment from three years to five years. The effect of this change in estimate for the year ended December 31, 2015 was a decrease in loss from operations and net loss of $1.7 million, respectively. The effect of this change in estimate was a decrease in net basic and diluted loss per share of $0.07 for the year ended December 31, 2015. Inventory Inventory is valued at the lower of the standard cost, which approximates actual cost, or market. Cost is determined using the first-in, first-out ("FIFO") method. Inventory consisted entirely of supplies, which are consumed when providing its test reports, and therefore does not maintain any finished goods inventory. The Company enters into inventory purchases and commitments so that it can meet future delivery schedules based on forecasted demand for its tests. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed below, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In August 2014, FASB issued Accounting Standards Update No. 2014 ‑15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (ASU 2014 ‑15). ASU 2014 ‑15 requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. In doing so, companies will have reduced diversity in the timing and content of footnote disclosures compared to footnote disclosures under today’s guidance. ASU 2014 ‑15 is effective for the Company in the first quarter of 2016 with early adoption permitted. The Company does not believe the impact of adopting ASU 2014 ‑15 on its financial statements will be significant. In May 2014, FASB issued Accounting Standards Update No. 2014 ‑09, Revenue from Contracts with Customers (ASU 2014 ‑09) to provide guidance on revenue recognition. ASU 2014 ‑09 requires a company to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under today’s guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. In August 2015, FASB issued ASU 2015-14, which defers the effective date of ASU 2014-09 for all entities by one year. ASU 2014-09 is effective for the Company in the first quarter of 2018. ASU 2014-09, as amended by ASU 2015-14, is effective for the Company in the fiscal year beginning after December 15, 2017, and interim periods within those years with early adoption permitted up to the first quarter of 2017. Upon adoption, ASU 2014 ‑09 can be applied retrospectively to all periods presented or only to the most current period presented with the cumulative effect of changes reflected in the opening balance of retained earnings in the most current period presented. The Company is currently evaluating the impact of adopting ASU 2014 ‑09 on its financial statements. In April 2015, FASB issued Accounting Standards Update No. 2015 ‑03, Interest—Imputation of Interest (Subtopic 835 ‑30): Simplifying the Presentation of Debt Issuance Costs (ASU 2015 ‑03). ASU 2015 ‑03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015 ‑03 is effective for the Company in the first quarter of 2016 with early adoption permitted. The Company does not believe the impact of adopting ASU 2015 ‑03 on its financial statements will be significant. In April 2015, FASB issued Accounting Standards Update No. 2015 ‑05, Intangibles—Goodwill and Other—Internal ‑Use Software (Subtopic 350 ‑40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement (ASU 2015 ‑05). ASU 2015 ‑05 provides guidance to clarify the customer’s accounting for fees paid in a cloud computing arrangement. ASU 2015 ‑05 is effective for the Company in the first quarter of 2016 with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2015 ‑05 on its financial statements. In July 2015, FASB issued Accounting Standards Update No. 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory (ASU 2015-11). ASU 2015-11 simplifies the subsequent measurement of inventory by replacing today’s lower of cost or market test with a lower of cost and net realizable value test. ASU 2015-11 is effective for the Company in the fiscal year beginning after December 15, 2016, and interim periods within those fiscal years. The Company is currently evaluating the impact of adopting ASU 2015 ‑11 on its financial statements. In November 2015, FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes , which simplifies the presentation of deferred taxes by requiring that deferred tax assets and liabilities be presented as noncurrent on the balance sheet. ASU 2015-17 is effective for the Company in the fiscal year beginning after December 15, 2016, and interim periods within those fiscal years. The Company is currently evaluating the impact of adopting ASU 2015 ‑17 on its financial statements. In February 2016, the FASB issued ASU No. 2016-2, Leases . ASU 2016-2 is aimed at making leasing activities more transparent and comparable, and requires substantially all leases be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. ASU 2016-2 is effective for the Company in the fiscal year beginning after December 15, 2018, and interim periods within those fiscal years with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2016-2 on its financial statements.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
Fair Value Measurements
Fair Value Measurements	3. Fair Value Measurements The Company's financial assets and liabilities carried at fair value are comprised of investment assets that include money market and investments, a liability for convertible preferred stock warrants and a liability for common stock warrants. The Company’s Credit Line described in Note 8 , is not measured at fair value on a recurring basis and is carried at amortized cost. The Company believes that the fair value of the Credit Line approximates its carrying value or amortized costs, due to the short-term nature of this obligation and the interest rate relative to market rates. The fair value accounting guidance requires that assets and liabilities be carried at fair value and classified in one of the following three categories: Level I: Quoted prices in active markets for identical assets and liabilities that the Company has the ability to access Level II: Observable market ‑based inputs or unobservable inputs that are corroborated by market data, such as quoted prices, interest rates, and yield curves Level III: Inputs that are unobservable data points that are not corroborated by market data. This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. There were no transfers between Level I, Level II and Level III during the periods presented. Assets and Liabilities That Are Measured at Fair Value on a Recurring Basis The following table represents the fair value hierarchy for the Company’s financial assets and financial liabilities measured at fair value on a recurring basis: December 31, 2015 December 31, 2014 Level I Level II Level III Total Level I Level II Level III Total (in thousands) Financial Assets: Money market deposits $ $ — $ — $ $ — $ — $ — $ — U.S. Treasury securities — — — — — — U.S. agency securities — — — — — — Municipal securities — — Total financial assets $ $ $ — $ $ — $ — $ — $ — Current Liabilities: Warrants $ — $ — $ $ $ — $ — $ $ Long-term Liabilities: Senior secured term loan $ — $ — $ — $ — $ — $ — $ $ Total financial liabilities $ — $ — $ $ $ — $ — $ $ The Company's warrants to purchase common stock are valued using Level III inputs; the Company used inputs from a Black-Scholes model with market volatility that is determined for comparable companies in the same business sector. The carrying amounts of cash, accounts receivable, and accounts payable approximate their fair value and are excluded from the table above. In April 2013, the Company entered into a senior secured term loan with a third ‑party lender, which consisted of a credit agreement, royalty agreement, warrants, and loan commitment. The Company considered the guidance under ASC 825 ‑10, Financial Instruments , which provides a measurement basis election for most financial instruments (i.e., either historical cost or fair value), allowing reporting entities to mitigate potential mismatches that arise under the current mixed measurement attribute model and ASC 820, Fair Value Measurements and Disclosures that provides for the fair value measurement of assets and liabilities, except for derivatives, for which the fair value is determined by ASC 815, Derivatives and Hedging . The Company evaluated the components of the senior secured term loan and determined that they we re derivatives to be evaluated under ASC 815 ‑15 ‑25 ‑1. The fair value accounting for derivatives is not an option , as derivatives must be fair valued under ASC 815 following the measurement guidance under ASC 820. Therefore, the Company engaged a third party to determine the fair value of the derivatives using the guidance of ASC 820 and recorded the Senior Secured Term Loan at fair value. ASC 815 requires the terms and features of an instrument that are not a derivative itself to be evaluated for embedded derivatives that must be bifurcated and separately accounted for as freestanding derivatives. In general, under ASC 815 ‑15 ‑25 ‑1, an embedded derivative is separated from the host contract and accounted for as a derivative instrument if and only if the following criteria are met: · Economic characteristics/risks of the derivative are not clearly and closely related to host; · The hybrid instrument is not re ‑measured at fair value under other applicable generally accepted accounting principles with changes in fair value reported in earnings as they occur; · A separate instrument with the same terms would be considered a derivative: (i) one or more underlying, (ii) One or more notional amounts, (iii) no or minimal initial net investment, (iv) net settlement. Based upon the Company's evaluation, the senior secured term loan constituted a liability with embedded derivative features that must be accounted for separately as mark-to-market instruments. In addition, adjustments to the embedded royalty feature were recorded as interest expense as they occurred, offset to the carrying amount of the debt (with the eventual cash outlay to settle such amounts recorded against the carrying amount of the debt). Based on the Company's evaluation, it was determined that the warrants granted were detachable and therefore a stand-alone component of the senior secured term loan which was to be fair valued using Level III inputs as a separate derivative. Additionally, it was determined that the remaining components were embedded derivatives of the senior secured term loan, which require d a fair value assessment using Level III inputs at the end of each reporting period. The Company's independent appraiser assisted in the evaluation of the components of the senior secured term loan that require d significant judgment or estimation. The fair value of the components were calculated using various techniques such as (i) discounted future cash flows, (ii) the income approach, using various revenue assumptions and applying a Monte-Carlo Simulation to each outcome and (iii) Black-Scholes Option Pricing Model with market volatility that was determined by comparison to comparable companies in the same business sector. The fair value of the senior secured term loan wa s re-measured at the end of each reporting period with the change in fair value recorded within non-operating expense in the statements of operations until it was repaid in October 2015. The following table provides a roll forward of the fair value, as determined by Level III inputs, of the warrants for the years ended December 31, 2015 and 2014: Warrants 2015 2014 (in thousands) Beginning balance $ $ Warrants exercised — Change in fair value Ending balance $ $ The following table provides a roll forward of the fair value, as determined by Level III inputs, of the senior secured term loan for the years ended December 31, 2015 and 2014: Term Loan 2015 2014 (in thousands) Beginning balance $ $ Change in fair value recognized in non-operating expense Loan payment — Ending balance $ — $ The early payment of the senior secured term loan included a prepayment penalty of $2.0 million and $5.3 million royalty payoff. The following table presents quantitative information about the inputs and valuation methodologies used for the Company’s fair value measurement classified in Level III of the fair value hierarchy at December 31, 2015. Weighted Average Interest on Fair Value at Significant Discount Rate December 31, 2015 Valuation Methodology Unobservable Input (range, if applicable) (in thousands) (in thousands) —Warrants $ Black-Scholes Option Pricing Model Volatility % Senior Secured Term Loan The fair value of the liability represented a term loan, royalty interest, and a loan commitment that was based upon the achievement of certain revenue targets over the life of the contract. The fair value of the liability was determined using discounted cash flow methodology, a Monte Carlo Simulation model for projected revenues, and the Longstaff-Schwartz model for royalty payments with significant inputs that include discount rate, projected revenues, projected royalty payments and percentage probability of occurrence for projected revenues and royalty payments. Warrants The significant unobservable inputs used in the fair value of warrants are derived from the Company's common stock valuation that is based upon a model with inputs from a Black-Scholes model and market volatility that is determined for comparable companies in the same business sector. The inherent risk in the market volatility is the selection of companies with similar business attributes to the Company. The Company changed the volatility assumption from a group of 15 companies that was shared with the secured debt volatility prior periods to a group of four companies that is shared with the volatility used for stock-based compensation expense. The Company determined this was appropriate as the secured debt was settled in October 2015 and results in consistent volatility assumptions used for both common stock warrants and stock-based compensation. This resulted in an increase of the Company’s warrant valuation of $0.2 million on December 31, 2015.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2015
Financial Instruments
Financial Instruments	4. Financial Instruments The Company elected to invest a portion of its cash assets in conservative, income earning, liquid investments effective September 2015. Cash equivalents and investments, all of which are classified as available-for-sale securities, consisted of the following: December 31, 2015 December 31, 2014 Amortized Cost Gross Unrealized Gain Gross Unrealized (Loss) Estimated Fair Value Amortized Cost Gross Unrealized Gain Gross Unrealized (Loss) Estimated Fair Value (in thousands) Money market deposits $ $ — $ — $ $ — $ — $ — $ — U.S. Treasury securities — — — — U.S. agency securities — — — — — Municipal securities Total $ $ $ $ $ — $ — $ — $ — Classified as: Cash equivalents $ $ — Short-term investments — Total $ $ — The Company invests in U.S. Treasuries, U.S. agency and high quality municipal bonds which mature at par and are all paying their coupons on schedule. Thus the Company has determined there is currently no other than temporary impairment of our investments, and will continue to recognize unrealized losses and gains in other comprehensive income. As of December 31, 2015, the Company has 73 investments in an unrealized loss position in its portfolio. The Company earned interest income of $0.3 million during the year ended December 31, 2015. The following table summarizes the Company’s portfolio of available-for-sale securities by contractual maturity as of December 31, 2015: December 31, 2015 Amortized Cost Fair Value (in thousands) Less than one year $ $ Greater than one year but less than five years Total $ $

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2015
Balance Sheet Components
Balance Sheet Components	5. Balance Sheet Components Allowance for Doubtful Accounts The following table presents a reconciliation of the allowance for doubtful accounts: December 31, December 31, 2015 2014 (in thousands) Beginning balance $ $ Provision for estimated bad debts Write offs Ending balance $ $ Property and Equipment, net The Company’s property and equipment consisted of the following: December 31, December 31, Useful Life 2015 2014 (in thousands) Machinery and equipment 3 - 5 years $ $ Furniture and fixtures 3 years Computer equipment 3 years Capitalized software held for internal use 3 years — Leasehold improvements Life of lease Construction-in-process Less: Accumulated depreciation and amortization Total Property and Equipment, net $ $ All of the Company’s long-lived assets are located in the United States. In September 2015, the Company paid off the Equipment Financing Facility, thus none of the Company's equipment is subject to pledge. The Company periodically evaluates the carrying value of long-lived assets when events or circumstances warrant such a review. The carrying value of a long-lived asset is considered impaired when the estimated realizable value of the asset is less than the carrying value of the asset. In that event, a loss is recognized based on the amount by which the carrying value exceeds the fair value of the long-lived asset. Fair value is determined based on the estimated realizable value of the long-lived asset. The Company recorded an asset impairment charge of $1.0 million against a specific group of machinery and equipment during the year ended December 31, 2015. The Company no longer uses this specific group of machinery and equipment because of outsourcing to its partners. The impairment charge was recorded to reflect reductions in the estimated realizable value of the machinery and equipment as a result of planning for its sale in the secondary market. The Company recorded the total impairment charge of $ 1.0 million in cost of product revenue. The Company sold some of the impaired machinery and equipment during the fourth quarter of 2015 for $0.5 million and classified the remaining impaired machinery and equipment as held for sale at the estimated realizable value of $0.2 million. The remaining impaired machinery was sold in January 2016 for $0.2 million. Accrued Compensation The Company’s accrued compensation consisted of the following: December 31, December 31, 2015 2014 (in thousands) Accrued paid time off $ $ Accrued commissions Accrued bonuses Other accrued compensation Total accrued compensation $ $ Other Accrued Liabilities The Company’s other accrued liabilities consisted of the following: December 31, December 31, 2015 2014 (in thousands) Accrued expenses $ $ Accrued rent Deferred lease obligation Accrued interest — Sales tax payable Total other accrued liabilities $ $

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies
Commitments and Contingencies	6. Commitments and Contingencies Operating Leases As of December 31, 2015, the Company sub ‑leases office facilities under non ‑cancelable operating lease agreements. In January 2013, the Company amended its sublease agreement to expand its corporate headquarters. In connection with the amendment, the Company executed a letter of credit in favor of the lessors for $0.8 million, which is secured with a restricted cash account. The related subleases expire in October 2016. On March 21, 2014, the Company entered into an additional sub ‑lease agreement to expand its corporate headquarters for additional office and laboratory space. In connection with the sub-lease, the Company executed a letter of credit in April 2015 in favor of the lessors for $0.3 million, which is secured with a restricted cash account. The lease and additional sub ‑lease expire in January 2017. In April 2015, the Company entered into a sub-lease agreement for additional office space in Redwood City, California. The additional space carries a base rent of $0.1 million per month. The lease period began in June 2015 and will terminate in August 2016 with no option to extend the lease. In addition, the Company paid a security deposit of $0.1 million. In September 2015, the Company’s subsidiary entered into a long-term lease agreement for lab and office space in Austin, Texas. The lease term is 132 months beginning in December 2015 with monthly payments beginning in December 2016, increasing from $0.1 million to $0.2 million. Per the terms of the lease, the subsidiary has paid a security deposit of $0.4 million, and the agreement provides for an allowance for leasehold improvements of up to $7.8 million. In October 2015, the Company’s subsidiary entered into a one year lease agreement for temporary office space in Austin, Texas. The property carries a monthly rent of $12,900 per month for the 12 months of the lease and $12,900 per month on a month to month basis following the 12 th month. The terms of the lease include a $12,900 security deposit In October 2015, the Company extended its corporate headquarters lease agreement for the lease of two spaces totaling approximately 88,000 square feet through October 5, 2023. Upon the expiree of the current lease, t he lease agreement commences in October 2016 at a monthly rent of $0.2 million per month and increase each year thereafter to a maximum of $0.4 million in the final year of the initial term of the l ease. The Company is entitled to a tenant improvement allowance of $0.4 million, to be expended prior to April 1, 2018, for the costs related to the design and construction of improvements to the facilities. The terms of the lease include a $0.5 million security deposit, and the option to extend the lease for an additional five years per the terms of the lease agreement. The future annual minimum lease payments under all non-cancelable operating leases as of December 31, 2015 are as follows: Operating Leases (in thousands) Year ending December 31: 2016 $ 2017 2018 2019 2020 2021 and thereafter Total future minimum lease payments $ Rent expense for the years ended December 31, 2015, 2014 and 2013 was $ 2.7 million, $1.5 million and $1. 3 million, respectively. The Company is also required to pay its share of facility operating expenses with respect to the facilities in which it operates. Legal Proceedings From time to time, the Company is involved in disputes, litigation, and other legal actions. The Company is aggressively defending its current litigation matters, and while there can be no assurances and the outcome of these matters is currently not determinable, the Company currently believes that there are no existing claims or proceedings that are likely to have a material adverse effect on its financial position. There are many uncertainties associated with any litigation and these actions or other third-party claims against the Company may cause the Company to incur costly litigation and/or substantial settlement charges. In addition, the resolution of any intellectual property litigation may require the Company to make royalty payments, which could adversely affect gross margins in future periods. If this were to occur, the Company's business, financial condition, results of operations, and cash flows could be adversely affected. The actual liability in any such matters may be materially different from the Company's estimates, if any, which could result in the need to record or adjust a liability and record additional expenses. During the periods presented, the Company has not recorded any accrual for loss contingencies associated with such legal proceedings, determined that an unfavorable outcome is probable or reasonably possible, or determined that the amount or range of any possible loss is reasonably estimable. On March 4, 2016, a lawsuit was filed against Natera in the Superior Court of the State of California for the County of San Diego, by a patient alleging that Natera failed to perform a test that was ordered. The complaint seeks unspecified damages. The Company has notified its insurer, who is providing a defense under a reservation of rights. The Company intend s to vigorously defend against the claims in this lawsuit, and assert any counterclaims that may be available to it, but cannot provide any assurance as to the ultimate outcome or that an adverse resolution of this lawsuit would not have a material adverse effect on its financial condition and results of operations. In light of, among other things, the early stage of the litigation, the Company is unable to predict the outcome of this matter and is unable to make a meaningful estimate of the amount or range of loss, if any, that could result from an unfavorable outcome. On February 17, 2016 and March 10, 2016 , two purported class action lawsuit s w ere filed in the Superior Court of the State of California for the County of San Mateo, against Natera, its directors and certain of its officers and 5% stockholders and their affiliates, and each of the underwriters of its July 1, 2015 initial public offering (the "IPO"). The complaint s assert claims under Sections 11, 12(a)(2) and 15 of the Securities Act of 1933, as amended. The complaint s allege, among other things, that the Registration Statement and Prospectus for the Company’s IPO contained materially false or misleading statements, and/or omitted material information that was required to be disclosed, about the Company’s business and prospects. Among other relief, the complaint s seek class certification, unspecified compensatory damages, rescission, attorneys' fees, and costs. The Company intends to defend the matter vigorously. The Company is still in the preliminary stages of reviewing the allegations made in the complaints, and cannot provide any assurance as to the ultimate outcome or that an adverse resolution would not have a material adverse effect on its financial condition and results of operations. In light of, among other things, the early stage of the litigation s , the Company is unable to predict the outcome and is unable to make a meaningful estimate of the amount or range of loss, if any, that could result from an y unfavorable outcome. On January 6, 2012, the Company filed a declaratory judgment action in the U.S. District Court for the Northern District of California, alleging that U.S. Patent No. 6,258,540 licensed by Sequenom, Inc. ("Sequenom") from Isis Innovation Limited, Inc. ("Isis") (the '540 patent), is invalid, unenforceable and not infringed by the Company. The '540 patent relates to non-invasive prenatal diagnosis methods. This case was consolidated in the Northern District of California with a case that Sequenom, an affiliate of Sequenom, and Isis brought on January 24, 2012 in the Southern District of California alleging infringement by the Company and DNA Diagnostics Center, Inc., the Company's licensee, and at the time, the distributor of its non-invasive paternity test, of certain claims of the '540 patent. Ariosa Diagnostics, Inc. ("Ariosa") and Verinata Health, Inc. ("Verinata"), now a division of Illumina, Inc., also filed declaratory judgment actions regarding the '540 patent against Sequenom in the Northern District. Sequenom asserted counterclaims of infringement of the '540 patent against both Ariosa and Verinata in those respective cases. All of these cases were designated related cases. On October 30, 2013, the District Court issued an order granting Ariosa's motion for summary judgment in its case against Sequenom, finding that the claims asserted against Ariosa are invalid under 35 U.S.C. §101 for reciting non-patentable subject matter. Many of the claims of the '540 patent asserted against the Company were invalidated by this order. Subsequently, Sequenom entered into stipulations with Verinata and the Company conditionally agreeing that the remaining asserted claims of the '540 Patent should be deemed invalid under 35 U.S.C. §101. The Court then entered judgment in favor of Verinata and the Company in their respective cases in November 2013. Sequenom has appealed all three judgments to the Court of Appeals for the Federal Circuit ("CAFC"). The CAFC has consolidated the Ariosa, Verinata and the Company's cases for purposes of appeal, such that the CAFC can make a single ruling on the '540 patent claims that apply to all parties involved. The appellate arguments were heard on November 7, 2014. On December 2, 2014, Sequenom and Verinata settled the pending claims between them. On June 12, 2015, the CAFC affirmed the district court's finding of invalidity with respect to the Company and Ariosa. On August 13, 2015, Sequenom requested a rehearing en banc by the full panel of the CAFC , and on October 19, 2015, the Company and Ariosa each filed a response to Sequenom’s request . On December 2, 2015, Sequenom’s petition for a rehearing en banc was denied. On March 21, 2016, Sequenom file d a petition for writ of certiorari with the Supreme Court . The Company intends to continue to vigorously assert its claims and defend against the counterclaims in this lawsuit, but it cannot be certain of the outcome. Third-Party Payer Reimbursement Audits In November 2014, a third-party payer sought information as part of an investigative audit of claims which it had paid for certain genetic testing. The Company complied with their request and provided responsive information. In a letter dated June 2, 2015, the third-party payer alleged that it had overpaid $1.9 million to the Company , which it claimed was an overpayment reflecting the difference between what it paid to the Company and what it contended it should have paid based on its fee schedule and coverage determinations . In August 2015, the Company reached an agreement for a settlement payment of $1.2 million as part of a complete settlement of this matter. This charge was recorded against revenue in the second quarter of 2015. Contractual Commitment As of December 31, 2015, the Company has non ‑cancelable contractual commitments with a supplier o f approximately $12.2 million and other material supplier commitments o f approximately $1.5 million in the aggregate for inventory material used in the laboratory testing process. In January 2015, the Company entered into a laboratory services agreement with a total remaining minimum of approximately $5.1 million through October 2016.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2015
Stock-Based Compensation
Stock-Based Compensation	7. Stock ‑Based Compensation Equity Plans 2015 Equity Incentive Plan General . Our board of directors adopted our 2015 Equity Incentive Plan, or our 2015 Plan, in June 2015. Our 2015 Plan replaced our 2007 Stock Plan. However, awards outstanding under the 2007 Plan will continue to be governed by the terms of the 2007 plan. Share Reserve . The initial number of shares of our common stock available for issuance under our 2015 Plan was 3,451,495 shares. As of December 31, 2015, 3,743,382 shares were available for issuance under the 2015 plan which includes unissued and forfeited shares from the 2007 plan. The number of shares reserved for issuance under the 2015 Plan will be increased automatically on the first business day of each of our fiscal years, commencing in 2016, by a number equal to the smallest of: · 3,500,000 shares; · 4% of the shares of common stock outstanding on the last business day of the prior fiscal year; or · the number of shares determined by our board of directors. In general, to the extent that any awards under the 2015 Plan are forfeited, terminate, expire or lapse without the issuance of shares, or if we repurchase the shares subject to awards granted under the 2015 Plan, those shares will again become available for issuance under the 2015 Plan, as will shares applied to pay the exercise or purchase price of an award or to satisfy tax withholding obligations related to any award. Eligibility. Employees, non-employee directors, consultants and advisors are eligible to participate in our 2015 Plan. Under our 2015 Plan, the aggregate grant date fair value of awards granted to our non-employee directors may not exceed $500,000 in any one fiscal year, except that the grant date fair value of awards granted to newly appointed non-employee directors may not exceed $1,000,000 in the fiscal year in which such non-employee director is initially appointed to our board of directors. Types of Awards. Our 2015 Plan provides for the following types of awards: · incentive and nonstatutory stock options; · stock appreciation rights; · restricted shares; · stock units; and · performance cash awards. Options and Stock Appreciation Rights. The exercise price for options granted under the 2015 Plan may not be less than 100% of the fair market value of our common stock on the grant date. Optionees may pay the exercise price in cash or, with the consent of the compensation committee by other approved methods. An optionee who exercises a stock appreciation right receives the increase in value of our common stock over the base price. The base price for stock appreciation rights may not be less than 100% of the fair market value of our common stock on the grant date. The settlement value of a stock appreciation right may be paid in cash, shares of our common stock or a combination. Options and stock appreciation rights vest as determined by the compensation committee. In general, they will vest over a four - year period following the date of grant. Options and stock appreciation rights expire at the time determined by the compensation committee but in no event more than ten years after they are granted. These awards generally expire earlier if the participant's service terminates earlier. No participant may be granted stock options or stock appreciation rights under our 2015 Plan covering more than 1,725,000 shares in any fiscal year, except that a new employee may receive stock options or stock appreciation rights covering up to 350,000 additional shares in the fiscal year in which employment commences. Restricted Shares and Stock Units. Restricted shares and stock units may be awarded under the 2015 Plan in return for any lawful consideration, and participant who receive restricted shares or stock units generally are not required to pay cash for their awards. In general, these awards will be subject to vesting. Vesting may be based on length of service, the attainment of performance-based milestones or a combination of both, as determined by the compensation committee. No participant may be granted restricted share awards or stock units with performance-based vesting covering more than 1,500,000 shares during any fiscal year, except that a new employee may receive restricted shares or stock units covering up to 300,000 additional shares in the fiscal year in which employment commences. Settlement of vested stock units may be made in the form of cash, shares of common stock or a combination. Performance Cash Awards. Performance cash awards may be granted under the 2015 Plan that qualify as performance-based compensation that is not subject to the income tax deductibility limitations imposed by Section 162(m) of the Internal Revenue Code, if the award is approved by our compensation committee and the grant or vesting of the award is tied solely to the attainment of performance goals during a designated performance period. No participant may be paid more than $5,000,000 in cash in any calendar year pursuant to a performance cash award granted under the 2015 Plan. To the extent a performance award is not intended to comply with Section 162(m) of the Internal Revenue Code, the compensation committee may select other measures of performance. Corporate Transactions. In the event we are a party to a merger, consolidation or certain change in control transactions, outstanding awards granted under the 2015 Plan, and all shares acquired under the 2015 Plan, will be subject to the terms of the definitive transaction agreement (or, if there is no such agreement, as determined by our compensation committee). The compensation committee is not required to treat all awards, or portions thereof, in the same manner. The vesting of an outstanding award may be accelerated by the administrator upon the occurrence of a change in control, whether or not the award is to be assumed or replaced in the transaction, or in connection with a termination of service following a change in control transaction. Changes in Capitalization. In the event of certain changes in our capital structure without our receipt of consideration, such as a stock split, reverse stock split or dividend paid in common stock, proportionate adjustments will automatically be made to the maximum number and kind of shares available for issuance under the 2015 Plan and outstanding stock award, if any as applicable. In the event that there is a declaration of an extraordinary dividend payable in a form other than our common stock in an amount that has a material effect on the price of our common stock, a recapitalization, a spin-off or a similar occurrence, the compensation committee may make such adjustments to any of the foregoing as it deems appropriate, in its sole discretion. Amendments or Termination. Our board of directors may amend or terminate the 2015 Plan at any time. If our board of directors amends the 2015 Plan, it does not need stockholder approval of the amendment unless required by applicable law, regulation or rules. The 2015 Plan will terminate automatically 10 years after the later of the date when our board of directors adopted the 2015 Plan or approved the latest share increase that was also approved by our stockholders. 2007 Stock Plan General. Our board of directors adopted our 2007 Plan in January 2007, and it was approved by our stockholders. No further awards have been made under our 2007 Plan after July 1, 2015 , the date of our initial public offering; however, awards outstanding under our 2007 Plan will continue to be governed by their existing terms. Share Reserve . As of December 31, 2015, we reserved 15,258,947 shares of our common stock for issuance under the 2007 Plan, all of which may be issued as incentive stock options. As of December 31, 2015, options to purchase 8,621,395 shares of common stock, at exercise prices ranging from $0.0065 to $12.8501 per share, or a weighted-average exercise price of $3.27 per share, were outstanding under the 2007 Plan. Administration . The compensation committee of our board of directors administer s the 2007 Plan and the administrator ha s complete discretion to make all decisions relating to the 2007 Plan and outstanding awards. Eligibility. Employees, non-employee members of our board of directors, consultants and advisors were eligible to participate in our 2007 Plan. Types of Awards . Our 2007 Plan provide s for the following types of awards: · incentive and nonstatutory stock options; and · restricted shares. Options. The exercise price for stock options granted under our 2007 Plan may not be less than 100% of the fair market value of our common stock on the grant date. Optionees may pay the exercise price in cash or cash equivalents or in one, or by any combination of, the following forms of payment, as permitted by the administrator in its sole discretion: · by delivery of a full-recourse promissory note, with the shares pledged as security against the principal and accrued interest on the note; · with shares of common stock that the optionee already owns; · by an immediate sale of the shares through a broker approved by us, if shares of our common stock are publicly traded; · by instructing us to withhold a number of shares having an aggregate fair market value that does not exceed the exercise price; or · by other methods permitted by applicable law. Options vest as determined by the administrator. In general, we granted options that vest over a four -year period following the date of grant. In most cases, options granted prior to 2011 (and prior to 2012 with respect to our executive officers) were immediately exercisable, subject to our right to repurchase unvested shares. Options expire at the time determined by the administrator, but in no event more than ten years after they we re granted, and generally expire earlier if the optionee's service terminates earlier. Restricted Shares. Restricted shares could be awarded or sold under the 2007 Plan in return for cash or cash equivalents or, as permitted by the administrator in its sole discretion, in exchange for services rendered to us, by delivery of a full-recourse promissory note or through any other means permitted by applicable law. Restricted shares vest as determined by the administrator. Corporate Transactions . In the event that we are a party to a merger or consolidation, shares acquired under the 2007 Plan will be subject to the agreement of merger or consolidation. Such agreement will provide for one or more of the following with respect to outstanding options: · the continuation, assumption or substitution of the option by the surviving entity or its parent; · full exercisability and vesting of the option, followed by cancellation if not exercised; or · cancellation of the option in exchange for a payment equal to the excess, if any, of the value that the holder of a share of our common stock receives in the transaction over the exercise price per share of the option. Such payment may be subject to vesting based on the optionee's continuing service, generally in accordance with the vesting schedule applicable to the option. The administrator is not obligated to treat all awards in the same manner. The administrator has the discretion, at any time, to provide that an award granted under the 2007 Plan will vest on an accelerated basis if we are subject to a change of control or if the participant is subject to an involuntary termination. Changes in Capitalization. In the event of certain specified changes in the capital structure of our common stock, such as a stock split, reverse stock split, stock dividend, reclassification or any other increase or decrease in the number of issued shares of stock effective without receipt of consideration by us, proportionate adjustments will automatically be made in each of the number of shares covered by each outstanding option under the 2007 Plan and the exercise price per share subject to each outstanding option. In the event of an extraordinary cash dividend that has a material effect on the fair market value of our common stock, a recapitalization, spin-off, or other similar occurrence, the administrator at its sole discretion may make appropriate adjustments in one or more of the number of shares covered by each outstanding option under our 2007 Plan and the exercise price per share subject to each outstanding option. Amendments or Termination. The administrator may at any time amend, suspend or terminate the 2007 Plan, subject to stockholder approval if the amendment increases the number of shares available for issuance or materially changes the class of persons eligible to receive incentive stock options. The 2007 Plan will terminate automatically 10 years after the later of the date when our board of directors adopted the 2007 Plan or approved the latest share increase that was also approved by our stockholders. 2015 Employee Stock Purchase Plan General . Our 2015 Employee Stock Purchase Plan, or 2015 ESPP, was adopted by our board of directors in June 2015 and our stockholders approved it in June 2015. The first offering period under our 2015 ESPP started on December 15, 2015. Our 2015 ESPP is intended to qualify under Section 423 of the Internal Revenue Code. Share Reserve. We have reserved 893,548 shares of our common stock for issuance under the 2015 ESPP. The number of shares reserved for issuance under the 2015 ESPP will automatically be increased on the first business day of each of our fiscal years, commencing in 2016, by a number equal to the least of: · 880,000 shares; · 1% of the shares of common stock outstanding on the last business day of the prior fiscal year; or · the number of shares determined by our board of directors. The number of shares reserved under the 2015 ESPP will automatically be adjusted in the event of a stock split, stock dividend or a reverse stock split (including an adjustment to the per-purchase period share limit). Administration. The compensation committee of our board of directors will administer the 2015 ESPP. Eligibility. All of our employees are eligible to participate if we employ them for more than 20 hours per week and for five or more months per year. Eligible employees may begin participating in the 2015 ESPP at the start of any offering period. Offering Periods. Each offering period will last a number of months determined by the compensation committee, not to exceed 27 months. A new offering period will begin periodically, as determined by the compensation committee. Offering periods may overlap or may be consecutive. Unless otherwise determined by the compensation committee, two offering periods of six months' duration will begin in each year on May 1 and November 1. However, if so determined by the compensation committee, the first offering period started on December 15, 2015 and will end on April 30, 2016, with the first purchase date occurring on April 29, 2016. Amount of Contributions. Our 2015 ESPP permits each eligible employee to purchase common stock through payroll deductions. Each employee's payroll deductions may not exceed 15% of the employee's cash compensation. Each participant may purchase up to the number of shares determined by our board of directors on any purchase date, not to exceed 5,000 shares. The value of the shares purchased in any calendar year may not exceed $25,000 . Participants may withdraw their contributions at any time before stock is purchased. Purchase Price. The price of each share of common stock purchased under our 2015 ESPP will not be less than 85% of the lower of the fair market value per share of common stock on the first day of the applicable offering period (or, in the case of the first offering period, the price at which one share of common stock is offered to the public in this offering) or the fair market value per share of common stock on the purchase date. Other Provisions . Employees may end their participation in the 2015 ESPP at any time. Participation ends automatically upon termination of employment with us. If we experience a change in control, our 2015 ESPP will end and shares will be purchased with the payroll deductions accumulated to date by participating employees. Our board of directors or our compensation committee may amend or terminate the 2015 ESPP at any time. Early Exercise of Employee Options As of December 31, 2015, the Company had approximately 1.3 million exercised and unvested shares outstanding that are subject to a repurchase right held by the Company at the original issuance price in the event that the optionee’s employment is terminated, either voluntarily or involuntarily. Effective in the year ended December 31, 2015, pursuant to the agreements with the option holders, the Company changed its estimated expiration of the Company’s repurchase right for 1.3 million exercised and unvested shares outstanding that are subject to repurchase right held by the Company through the 210 days after the date of the prospectus filed in connection with the Company’s IPO. Accordingly the unrecognized compensation expense is being accelerated over a shorter performance period through January 2016. As a result of this acceleration, the Company recorded an additional $1.3 million in stock-based compensation expense during the year ended December 31, 2015. Stock Options The following table summarizes option activity for the years ended December 31, 2015, 2014 and 2013: Outstanding Options Weighted- Weighted- Average Shares Average Remaining Aggregate Available for Number of Exercise Contractual Intrinsic (in thousands, except for contractual life and exercise price) Grant Shares Price Life Value (In years) Balance at December 31, 2014 $ 8.83 $ Additional shares authorized — Options granted $ Options exercised — $ Options forfeited $ Balance at December 31, 2015 $ 8.31 $ Exercisable at December 31, 2015 $ 5.31 $ Vested and expected to vest at December 31, 2015 $ 7.32 $ The total intrinsic value of stock options exercised during the years ended December 31, 2015, 2014 and 2013 was $6.9 million, $1.2 million and $0.7 million, respectively. The total fair value of stock options vested during the years ended December 31, 2015, 2014 and 2013 was $4.5 million $4.1 million and $1.0 million, respectively. The weighted-average grant date fair value of options granted during the years ended December 31, 2015, 2014 and 2013 was $7.29 , $3.28 and $0.99 per share, respectively. Stock ‑Based Compensation Expense Employee and non ‑employee stock ‑based compensation expense was calculated based on awards ultimately expected to vest and have been reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods, if actual forfeitures differ from those estimates. The following table presents the effect of employee and non ‑employee stock ‑based compensation expense on selected statements of operations line items for the years ended December 31, 2015, 2014 and 2013. Year ended December 31, 2015 2014 2013 Employee Non-Employee Total Employee Non-Employee Total Employee Non-Employee Total (in thousands) Cost of revenues $ $ $ $ $ $ $ $ $ Research and development Selling, general and administrative Total $ $ $ $ $ $ $ $ As of December 31, 2015, approximately $14.7 million of unrecognized compensation expense, adjusted for estimated forfeitures, related to unvested stock options will be recognized over a weighted ‑average period of approximately 1.96 years. Valuation of Stock Option Grants to Employees The Company estimates the fair value of its stock options granted to employees on the grant date using the Black ‑Scholes option ‑pricing model. The fair value of employee stock options is amortized on a straight ‑line basis over the requisite service period of the awards, generally the vesting period. The fair value of employee stock options was estimated using the following assumptions: Year ended December 31, 2015 2014 2013 Expected term 5.6 — 10.0 4.91 — 7.06 6.0 Expected volatility 69.7 % — 78.8 % 73.4 % — 87.0 % 63.7 % — 85.7 % Expected dividend rate % % % Risk-free interest rate 1.56 % — 2.32 % 1.65 % — 2.04 % 0.44 % — 2.86 % Expected Term : The expected term of options represents the period of time that options are expected to be outstanding. The Company's historical stock option exercise experience does not provide a reasonable basis upon which to estimate an expected term due to a lack of sufficient data. For granted "at-the-money" stock options, the Company estimates the expected term by using the simplified method permitted by the Securities and Exchange Commission. The simplified method calculates the expected term as the average of the time-to-vesting and the contractual life of the options. For stock options that are not granted "at-the-money," the Company uses the binomial lattice model to calculate the expected term. Expected Volatility : The Company derived the expected volatility from the average historical volatilities of comparable publicly traded companies within its peer group over a period approximately equal to the expected term. Expected Dividend Rate : The Company has not paid and does not anticipate paying any dividends in the near future. Risk-Free Interest Rate : The risk-free interest rate assumption is based on U.S. Treasury yield in effect at the time of grant for zero coupon U. S. Treasury notes with maturities approximately equal to the expected term. Valuation of Stock Option Grants to Non-Employees Total options outstanding as of December 31, 2015, include 0.2 million options that were granted to non-employees, of which 0.1 million options are unvested. Stock-based compensation expense related to stock options granted to non-employees is recognized as the stock option is earned and the services are rendered. The Company believes that the estimated fair value of the stock options is more readily measurable than the fair value of the services rendered. The fair value of the stock options granted to non-employees is calculated at each reporting date using the Black-Scholes options-pricing model with the following assumptions: Year ended December 31, 2015 2014 2013 Expected term 4.9 — 9.8 4.4 — 10.0 8.4 Expected volatility 70.2 % — 75.4 % 71.9 % — 80.2 % 75.6 % — 81.5 % Expected dividend rate % % % Risk-free interest rate 1.74 % — 2.24 % 1.41 % — 2.61 % 1.44 % — 2.51 %

Debt

Debt	12 Months Ended
	Dec. 31, 2015
Debt
Debt	8. Debt Senior Secured Term Loan In April 2013, as amended in June 2014, the Company entered into a senior secured term loan arrangement (the "Secured Loan Arrangement") with ROS Acquisition LP ("ROS"). The Secured Loan Arrangement provided for up to $40.0 million in borrowing capacity ("Credit Agreement"), a warrant to purchase shares of Common Stock, and an agreement to pay royalties on Company revenues ("Royalty Agreement"). The Company borrowed $20.0 million on the effective date of the Credit Agreement. The Credit Agreement provided for an interest rate equal to the greater of (a) LIBOR or (b) 1% per annum plus the applicable margin of 8% per annum or 9% floor on the outstanding balance of the term loan. The Royalty Agreement obligated the Company to make royalty payments of 1% applied to total Company fiscal year revenues of up to $50.0 million and 1.5% applied to fiscal year incremental revenues above $50.0 million. For the year ended December 31, 2015, the Company incurred approximately $1.4 million and $ 7.1 million in interest expenses under the Credit Agreement and royalty expenses under the Royalty Agreement, respectively. The $7.1 million in royalty expense include d $1.8 million in royalty due and the remainder was for part of the $28.0 million pay-off to ROS. Please refer to paragraph below for pay-off details. For the year ended December 31, 2014, the Company incurred approximately $1.8 million and $2.2 million in interest expenses under the Credit Agreement and royalty expenses under the Royalty Agreement, respectively. For the year ended December 31, 2013, the Company incurred approximately $1.3 million and $0.5 million in interest expenses under the Credit Agreement and royalty expense under the Royalty agreement, respectively. The interest on the loan is set forth in the financial statements as interest expense below loss from operations. The effective yield was approximately 20.9% , 19.8% and 12.6% , respectively, for the year ended December 31, 2015, 2014 and 2013, excluding royalty and interest early termination payments. Under the terms of the Secured Loan Arrangement, the Company issued ROS a warrant to purchase 376,691 shares of common stock with an exercise price of $2.3229 per share. The Credit Agreement principal is due and payable on April 18, 2019. The Company could at its option, prepay the term loan borrowings subject to a prepayment premium equivalent to 10% of the outstanding principal. Prepayment of the amount due under the Credit Agreement d id not eliminate the royalty payment obligation, which if not terminated, would have expire d no later than April 18, 2023. ROS maintained a security interest in substantially all of the Company's tangible and intangible assets, including intellectual property, to secure any outstanding amounts under the Credit Agreement. The Credit Agreement contained customary events of default, conditions to borrowing and covenants, including restrictions on the ability to dispose of assets, make acquisitions, incur debt, incur liens and make distributions to stockholders, including dividends. The Credit Agreement also included a financial covenant requiring the maintenance of minimum liquidity of $5.0 million and minimum revenue thresholds. During the continuance of an event of a default, ROS could have accelerate d amounts outstanding, terminate the credit facility and foreclose on all collateral. The Company was in compliance with all covenants under the terms of the Secured Loan Arrangement with ROS throughout the life of the loan. In October 2015, the Company paid off the entire $20.0 million in borrowings under the Secured Loan Arrangement with ROS. The Company made a payment of $28.0 million to ROS, comprising $20.0 million in principal, $2.0 million ( 10% outstanding principal) in prepayment penalty and $6.0 million (which includes royalty amounts for third quarter 2015 transactions and the cost to extinguish the liability) in royalty payment applied toward the royalty obligation. This payment released the Company from all future loan payments, royalty payments and all associated liens securing the loan. Credit Line Agreement In September 2015, the Company entered into the Credit Line with UBS providing for a $50.0 million revolving line of credit which can be drawn down in increments at any time. In October 2015, the Company borrowed $32.0 million against the Credit Line, primarily to prepay all outstanding amounts under the Secured Loan Arrangement with ROS. The Credit Line bears interest at 30 -day LIBOR plus 0.65% , and equals approximately 0.84% per annum at the time of the draw. In November, 2015, the Company borrowed an additional $10.0 million which bears interest at approximately 0.85% per annum. The Credit Line is secured by a first priority lien and security interest in the Company’s money market and marketable securities held in its managed investment account with UBS. UBS has the right to demand full or partial payment of the Credit Line Obligations and terminate the Credit Line, in its discretion and without cause, at any time. Equipment Financing Facility In April 2013, the Company entered into an equipment financing facility (the “Equipment Financing Facility”) with a financial institution pursuant to which the Company could borrow up to $5.0 million to fund equipment purchases. The financial institution maintained a security interest in the underlying equipment until payment in full of the loan. The loan bore interest at the financial institution's prime reference rate (defined as the 30-day LIBOR rate plus 2.50%) plus 4.10% , which equaled 7.35% upon closing of the agreement. In December 2014, the Company amended the Equipment Financing Facility increasing the loan amount to $5.9 million to fund equipment purchased. The Company paid interest on the unpaid principal at the financial institution's prime reference rate plus 3.10% , which equaled 6.35% . Under the terms of the Equipment Financing Facility, the loan would mature on May 31, 2017. Under the terms of the Equipment Financing Facility, the Company would be required to make 30 payments of principal and interest through the maturity of the loan in May 2017. In September 2015, the Company paid off the remaining principal balance of the equipment financing facility. The Company made a payment of $4.1 million, comprising of principal, interest and administrative fees settling all of its obligations under the loan.

Warrants

Warrants	12 Months Ended
	Dec. 31, 2015
Warrants.
Warrants	9. Warrants In 2007, the Company issued warrants to purchase an aggregate of 24,538 shares of common stock at an exercise price of $0.0978 per share to various holders. As of December 31, 2015, these warrants were fully exercised. In 2009, the Company granted warrants to purchase 33,742 shares of Series B convertible preferred stock at an exercise price of $1.8908 per share. The warrants were granted to a financial institution in connection with a secured equipment loan and expire on November 2, 2019. In connection with the IPO in July 2015, these warrants were converted into the right to purchase common stock at a one -to-one ratio. In December 2015, the financial institution net-exercised all 33,742 of their warrant shares at the strike price of $1.8908 per share. Based on the Natera closing price of $11.57 per share on the prior business day, Natera issued 28,227 shares to the financial institution. In April 2014, the Company granted warrants to purchase approximately 376,691 warrant s to purchase common stock at an exercise price of $2.3229 per common share . The warrants were granted to ROS Acquisition Offshore LP in connection with our senior secured term loan and expire on April 18, 2023 . It was determined that the warrants granted are detachable and therefore are a stand-alone component of the senior secured term loan to be fair valued using Level III inputs as a separate derivative. As of December 31, 2015, these warrants remained exercisable for common stock . In connection with the Series F financing, the Series E preferred stockholders agreed to change the liquidation preference from two times to one times the liquidation value as described in the agreement. In exchange, on November 20, 2014, the Company issued common stock warrants to the Series E preferred stockholders to purchase 429,440 shares at $0.0163 per share. The warrants are carried in Additional Paid In Capital and the issuance of the warrants was treated as a deemed dividend by the common stockholder out of Additional Paid in Capital. In connection with the IPO in July 2015, such warrants were automatically net exercised into 429,042 shares of common stock.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2015
Convertible Preferred Stock.
Convertible Preferred Stock	10. Convertible Preferred Stock At the closing of the IPO in July 2015, 31, 397,221 shares of outstanding convertible preferred stock were automatically converted into common stock on a one-to-one basis. Following the IPO, there were no shares of preferred stock outstanding. In connection with the IPO, the Company amended and restated its Amended and Restated Certificate of Incorporation to change the authorized capital stock to 750.0 million shares designated as common stock and 50.0 million shares designated as preferred stock, all with a par value of $0.0001 per share. As of December 31, 2014, the convertible preferred stock consisted of the following: Shares Shares Issued and Liquidation Proceeds, net of Series Authorized Outstanding Amount Issuance Costs (in thousands) A-1 $ $ A B C D E F $ $ Each share of Series A-1, Series A, Series B, Series C, Series D, Series E and Series F convertible preferred stock was convert ible , at the option of the holder, into that number of fully paid and non-assessable shares of common stock that wa s equal to $0.0065 , $0.7987 , $1.8908 , $2.2168 , $4.8819 , $6.0199 , and $12.7629 per share, respectively (as adjusted for stock splits, combinations, and reorganizations), divided by the conversion price of $0.0065 , $0.7987 , $1.8908 , $2.2168 , $4.8819 , $6.0199 , and $12.7629 , respectively (as adjusted for stock splits, combinations, and reorganizations). Additionally, each share of convertible preferred stock automatically converted into shares of common stock at the conversion rate at the time in effect for such series of convertible preferred stock immediately upon the earlier of: (i) the Company's sale of its common stock in a firm commitment underwritten public offering pursuant to a registration statement on Form S-1 under the Securities Act of 1933, as amended, the public offering price of which was not less than $40.0 million in the aggregate; or (ii) the date specified by written consent or agreement of the holders of a majority of the then outstanding shares of convertible preferred stock (voting together as a single class and not as separate series, and on an as-converted basis); provided, however, that an automatic conversion of the outstanding shares of Series E convertible preferred stock pursuant to clause (ii) above require d the written consent or agreement of the holders of at least seventy percent of the outstanding shares of Series E convertible preferred stock unless such conversion is in connection with (x) an underwritten public offering of this corporation or (y) a bona fide financing transaction with a pre-money equity valuation on an as converted, fully diluted basis of less than $100.0 million that results in a recapitalization of the Company, in which case on the consent of the holders of a majority of the then outstanding shares of convertible preferred stock (voting together as a single class and not as separate series, and on an as-converted basis) was required to convert each share of convertible preferred stock. Series A and Series B preferred stockholders could elect two Board members (voting together as a single class) and Series C preferred stockholders could elect one Board member. No Board member ha d been elected at this time for the Series C convertible preferred stock. The holders of shares of convertible preferred stock were entitled to receive dividends, on an equal basis, out of any assets legally available thereof, prior and in preference to any declaration or payment of any dividend (payable other than in common stock or other securities and rights convertible into or entitling the holder thereof to receive, directly or indirectly, additional shares of common stock of this corporation) on the common stock of this corporation, at the applicable Dividend Rate (as defined below), payable when, as, and if declared by the Board. Such dividends were cumulative. Dividend Rate means $0.0639 per annum for each share of Series A convertible preferred stock, $0.0005 per annum for each share of Series A-1 convertible preferred stock, $0.1513 per annum for each share of Series B convertible preferred stock, $0.1773 per annum for each share of Series C convertible preferred stock, $0.3911 per annum for each share of Series D convertible preferred stock, $0.4817 per annum for each share of Series E convertible preferred stock, and $1.021 per annum for each share of Series F convertible preferred stock (each as adjusted for any stock splits, stock dividends, combinations, subdivisions, or recapitalizations). In the event of a Company liquidation, the holders of Series E and Series F convertible preferred stock were entitled to receive, prior and in preference to any distribution of the proceeds of such liquidation to the holders of Series A, Series A-1, Series B, Series C, and Series D convertible preferred stock by reason of their ownership thereof, an amount per share equal to the sum of the original issue price for the Series E and Series F convertible preferred stock, plus declared and unpaid dividends on such shares. The holder of each share of convertible preferred stock ha d the right to one vote for each share of common stock into which such preferred stock could be converted and such holder ha d full voting rights and powers equal to the voting rights and powers of the holders of common stock, and wa s entitled to notice of any stockholders' meeting in accordance with the bylaws of the Company, except as provided for the election of directors by separate class vote of the holders of common stock, and wa s entitled to vote, together with holders of common stock, with respect to any question upon which holders of common stock have the right to vote. The Series A and Series B preferred stockholders could elect one director (voting together as a single class, not as a separate series and on an as-converted basis) and Series C preferred stockholders could elect one director at any election of directors.

CommonStock

CommonStock	12 Months Ended
	Dec. 31, 2015
Common Stock.
Common Stock	11. Common Stock The Company's Certificate of Incorporation, as restated in connection with the closing of the IPO, authorizes the Company to issue 750.0 million shares of common stock with a par value of $0.0001 per share. As of December 31, 2015 and December 31, 2014, the Company had 50.3 million and 6.9 million shares of common stock outstanding, respectively. Each shareholder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders. The Company's board of directors and stockholders approved an amendment to its Certificate of Incorporation to effect a 1 -for-1.63 reverse split of its capital stock, which was effected on June 19, 2015. All references to common stock, options to purchase common stock, restricted stock, share data, per share data, warrants, convertible preferred stock and related information have been retroactively adjusted where applicable in this report to reflect the reverse stock split of the Company's capital stock as if it had occurred at the beginning of the earliest period presented.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Taxes
Income Taxes	12. Income Taxes The Company's effective tax rates for the years ended December 31, 2015 and 2014 differ from the U.S. federal statutory rate as follows: December 31, 2015 2014 (in thousands, except percentages) U.S. federal taxes (benefit) at statutory rate $ % $ % State tax expense % % Research and development credits % % Stock-based compensation % % Mark to market fair value adjustments % % Other nondeductible items % % Change in valuation allowance % % Provision for income taxes $ — — % $ % Due to its history of operating losses, the Company has not recorded any income tax expense for the years ended December 31, 2015 and December 31, 2014, except for $15 thousand of state income tax expense in 2014 . As the provision for income taxes is not significant for 2015 and 2014, any income taxes have been reclassed in other income and expenses. Deferred income taxes reflect the net tax effects of temporary differences between carrying amounts of assets and liab ilities for financial reporting purposes and the amounts used for income tax purposes as well as net operating loss and tax credit carryforwards. Th e components of the net deferred income tax assets are as follows : December 31, 2015 2014 (in thousands) Deferred tax assets Net operating loss carryforwards $ $ Research and development tax credit carryforwards Reserves and accruals Stock-based compensation Total deferred tax assets before valuation allowance Less: valuation allowance Deferred tax liabilities Property and equipment Net deferred tax assets $ — $ — The Company established a full valuation allowance against its net deferred tax assets in 2015 and 2014 due to the uncertainty surrounding realization of these assets. The valuation allowance increased by $24.5 million, $0.9 million and $10.8 million during the years ended December 31, 2015, 2014 and 2013, respectively. As of December 31, 2015, the Company had federal and state net operating loss (NOLs) carryforwards of approximately $114.5 million and $73.2 million, respectively, which begin to expire in 2027 and 2017, respectively, if not utilized. The deferred tax assets related to NOLs do not include excess tax benefits from employee stock option exercises. Equity will be increased by $1.4 million, if and when such deferred tax assets are ultimately realized. The Company uses ASC 740 ordering when determining when excess tax benefits have been realized. The Company also had federal research and development credit carryforwards of approximately $4.6 million, which begin to expire in 2027, and state research and development credit carryforwards of approximately $3.4 million, which can be carried forward indefinitely. Realization of these deferred tax assets would require $138.8 million in taxable income to fully utilize. Realization is dependent on generating sufficient taxable income prior to expiration of the loss and credit carryforwards. Federal and California tax laws impose substantial restrictions on the utilization of NOLs and credit carryforwards in the event of an "ownership change" for tax purpose, as defined in Section 382 of the Internal Revenue Code. Accordingly, the Company's ability to utilize these carryforwards may be limited as the result of such ownership change. Such a limitation could result in limitation in the use of the NOLs in future years and possibly a reduction of the NOLs available. A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows: December 31, 2015 2014 (in thousands) Balance at beginning of year $ $ Additions based on tax positions related to the current year Additions for tax positions of prior years — — Balance at end of year $ $ The Company adopted the provisions of ASC 740-10-50, Accounting for Uncertainty in Income Taxes , on January 1, 2009. During the years ended December 31, 2015 and 2014, the amount of unrecognized tax benefits increased $1.0 million and $0.5 million, respectively, due to additional research and development credits generated during the year. As of December 31, 2015 and 2014, the total amount of unrecognized tax benefits was $2.4 million and $1.4 million, respectively. The reversal of the uncertain tax benefits would not affect the Company's effective tax rate to the extent that it continues to maintain a full valuation allowance against its deferred tax assets. The Company is subject to U.S. federal income taxes and to income taxes in various states in the United States. Tax regulations within each jurisdiction are subject to the interpretation of the related tax laws and regulations, and require significant judgment to apply. The Company is subject to U.S. federal, state and local tax examinations by tax authorities for all prior tax years since incorporation. The Company does not anticipate significant changes to its current uncertain tax positions through December 31, 2016. The Company recognizes any interest and/or penalties related to income tax matters as a component of income tax expense. As of December 31, 2015, there were no accrued interest and penalties related to uncertain tax positions.

Related_Party Transactions

Related‑Party Transactions	12 Months Ended
	Dec. 31, 2015
Related‑Party Transactions
Related‑Party Transactions	13. Related ‑Party Transactions The chief executive officer of the Company received a monthly payment based on his use for Company business purposes of an apartment that he owned in New York City. For the years ended December 31, 2015, 2014 and 2013, the Company expensed $9,500 , $22,800 and $22,642 , respectively . The Company ceased making payments for this property following the sale of the apartment during the second quarter of 2015. The Company entered into a full recourse promissory note with the Company’s chief executive officer, in April 2012. Pursuant to this note, which was secured by a stock pledge agreement, the Company loaned Dr. Rabinowitz $154,000 . This interest only loan bore interest at a rate per annum of 1.15% , compounded annually. This loan, including all accrued interest, was repaid in full by Dr. Rabinowitz in May 2015. The Company entered into a full recourse promissory note with Jonathan Sheena, the Company’s chief technology officer, in April 2012. Pursuant to this note, which was secured by a stock pledge agreement, the Company loaned Mr. Sheena $38,280 . This interest only loan bore interest at a rate per annum of 1.15% , compounded annually. This loan, including all accrued interest, was repaid in full by Mr. Sheena in May 2015.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2015
Net Loss per Share
Net Loss per Share	14. Net Loss per Share Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period. Prior to the Company’s IPO of its common stock, the Company’s convertible preferred stock was entitled to receive dividends, prior and in preference to any declaration or payment of any dividend on common stock and thereafter participate pro rata on an as converted basis with the common stock holders on any distributions to common stockholders. The convertible preferred shares were therefore considered to be participating securities. As a result, the Company calculated the net loss per share using the two-class method. Accordingly, the net loss attributable to common stockholders is derived from the net loss for the period and, in periods in which the Company has net income attributable to common stockholders, an adjustment is made for the noncumulative dividends and allocations of earnings to participating securities based on their outstanding shareholder rights. Under the two-class method, the net loss attributable to common stockholders is not allocated to the convertible preferred stock as the convertible preferred stock did not have a contractual obligation to share in the Company’s losses. The diluted net income per share attributable to common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. In periods when the Company has incurred a net loss, convertible preferred stock, options to purchase common stock, common stock warrants and common stock subject to repurchase are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is antidilutive. The following table provides the basic and diluted net loss per common share computations for the years ended December 31, 2015, 2014 and 2013. Year ended December 31, (in thousands, except per share data) 2015 2014 2013 Basic and diluted loss per share: Net loss $ $ $ Net loss attributable to common shares, basic and diluted Weighted-average common shares outstanding Less: weighted-average unvested common shares subject to repurchase Weighted-average number of shares used in computing net loss per share, basic and diluted Basic and diluted net loss per share $ $ $ Potentially dilutive shares that were not included in the diluted per share calculations because they would be anti ‑dilutive as of the years ended December 31, 2015, 2014 and 2013 were as follows: Year ended December 31, 2015 2014 2013 Options to purchase common stock Warrants to purchase common stock Common stock subject to repurchase Convertible preferred stock —

Geographic Information

Geographic Information	12 Months Ended
	Dec. 31, 2015
Geographic Information
Geographic Information	15. Geographic Information The following table presents total revenues by geographic area based on the location of the Company’s customers: Year ended December 31, (in thousands) 2015 2014 2013 United States $ $ $ Americas, excluding U.S. Europe, Middle East, India, Africa Other Total $ $ $

Quarterly Financial Data

Quarterly Financial Data	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Data
Quarterly Financial Data	16 . Quarterly Financial Data (unaudited) Three months ended December 31, September 30, June 30, March 31, (in thousands, except per share data) 2015 Operating results: Total revenues $ $ $ $ Cost of product revenues Gross profit Other costs and expenses Interest expense and other income (expense), net Net loss Per share data: Net income - basic and diluted $ $ $ $ 2014 Operating results: Total revenues $ $ $ $ Cost of product revenues Gross profit Other costs and expenses Interest expense and other income (expense), net Net income (loss) Per share data: Net income - basic $ - $ $ $ Net income - diluted -

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events
Subsequent Events	17 . Subsequent Events None.

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”). .
Need to Raise Additional Capital	Need to Raise Additional Capital The Company has incurred net losses since its inception and anticipates net losses and negative operating cash flows for the near future. For the year ended December 31, 2015, the Company had a net loss of $ 70.3 million, and as of December 31, 2015, it had an accumulated deficit of $ 250.1 million . At December 31, 2015, the Company had $ 28.9 million in cash and cash equivalents and $201.6 million in marketable securities. While the Company has introduced multiple products that are generating revenues, these revenues have not been sufficient to fund all operations. Accordingly, the Company has funded the portion of operating costs that exceeds revenues through a combination of equity issuances, debt issuances, and other financings. The Company expects to develop and commercialize future products and, consequently, it will need to generate additional revenues to achieve future profitability and may need to raise additional equity or debt financing that may not be available, if at all, at terms acceptable to the Company to fund future operations. Based on our current business plan, we believe that our existing cash and marketable securities will be sufficient to meet our anticipated cash requirements for the next 12 months.
Principles of Consolidation	Principles of Consolidation The accompanying condensed consolidated financial statements include all the accounts of the Company and its subsidiary. The Company established a subsidiary that operates in the state of Texas in December 2014 to support the Company’s laboratory and operational functions, which became active in the second quarter of 2015. All intercompany balances and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions about future events that affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Significant items subject to such estimates include the allowance for doubtful accounts, accrued liability for potential refund requests, stock-based compensation, the fair value of common stock and fair value of debt accounted for under ASC 815, as well as income tax uncertainties. These estimates and assumptions are based on management's best estimates and judgment. Management regularly evaluates its estimates and assumptions using historical experience and other factors; however, actual results could differ from these estimates and could have an adverse effect on the Company's financial statements.
Fair Value	Fair Value The Company discloses the fair value of financial instruments for financial assets and liabilities for which the value is practicable to estimate. Fair value is defined as the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The Company carried senior secured term loan and warrants at fair value according to the fair value measurement guidance.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash and money market deposits with financial institutions.
Restricted Cash	Restricted Cash The Company discloses both short-term and long-term restricted cash. Short-term restricted cash consists of $0.8 million, securing our letter of credit for our headquarters operating lease which expires in October 2016 and $0.1 million in payments received by certain customers. Long-term restricted cash consists of $0.4 million deposit per credit card terms and $0.3 million securing our letter of credit for our headquarters operating lease which expires in January 2017.
Investments	Investments Management determines the appropriate classification of securities at the time of purchase and reevaluates such determination at each balance sheet date. The Company generally classifies its entire investment portfolio as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company classifies all investments as short-term, even though the stated maturity may be more than one year from the current balance sheet date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity (deficit).
Risk and Uncertainties	Risk and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash, accounts receivable and investments. The Company limits its exposure to credit loss by placing its cash in financial institutions with high credit ratings. The Company's cash may consist of deposits held with banks that may at times exceed federally insured limits. The Company performs evaluations of the relative credit standing of these financial institutions and limits the amount of credit exposure with any one institution. The Company bills third-party payers for certain tests performed. The amount that is ultimately received from the payer for our claim and the timing of such payments are subject to the determination of the payer based on the nature of the test performed and their view of our business practices with respect to collections of plan deductibles and co-payments from patients and other activities. This determination can impact both the amount and timing of when our invoices are collected. Payers may also withhold payments and request refunds of prior payments if we do not perform in accordance with the policies of these payers. The Company performs evaluations of financial conditions for clinics and laboratory partners and generally does not require collateral to support credit sales. For 2015 and 2014, there were no customers exceeding 10% in total revenue. For 2013, two customers accounted for more than 10% of our revenues: Quest Diagnostics Incorporated ( 16% ) and Progenity, Inc. ( 12% ) . As of December 31, 2015 and 2014, no customers had a receivable balance greater than 10% of net accounts receivable, and as of December 31, 2013, two customers had receivable balances of 37% a nd 18% of total accounts receivable .
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts Trade accounts receivable are recorded at the amount billed to the laboratory partners and clinics. Reducing this amount is an allowance for doubtful accounts for estimated losses resulting from the inability of its customers to make the contracted payments. Management analyzes accounts receivable and historical bad debt experience, customer creditworthiness, current economic trends, and changes in customer payment history when evaluating the adequacy of the allowance for doubtful accounts. Accounts receivable are written off against the allowance when there is substantive evidence that the account will not be paid.
Revenue Recognition	Revenue Recognition The Company generally bills an insurance carrier, a clinic or a patient for the test upon delivery of the test result. The Company also bills patients directly for out-of-pocket costs not covered by their insurance carriers representing co-pays and deductibles in accordance with their insurance carrier and health plans. The Company may not get reimbursed for tests completed if the tests are not covered under the insurance carrier’s reimbursement policies or the Company is not a qualified provider to the insurance carrier. For tests performed, where an agreed upon reimbursement rate or fixed fee and a predictable history or likelihood of collections exists, the Company recognizes revenues upon delivery of the test report to the prescribing physician based on the established billing rate less contractual and other adjustments, such as an allowance for doubtful accounts, to arrive at the amount that the Company expects to collect. In all other situations, as the Company does not have a sufficient history of collection and is not able to determine collectability, the Company recognizes revenues when cash is received. From time to time, we receive requests for refunds of payments previously made by insurance carriers. The Company has established an accrued liability for potential refund requests based on our experience. In cases where the Company sells its tests through its laboratory partners, the majority of the laboratory partners bill the patient, clinic, or insurance carrier for the performance of the Company's tests. For tests sold through a limited number of its laboratory partners, the Company bills directly to a patient, clinic or insurance carrier, or a combination of the insurance carrier and patient for the fees. The Company considers its services rendered when it delivers reports of its test results to the laboratory partner, clinic or patient. When the Company has contracted fixed rates for its services and collectability of its revenues is reasonably assured, it recognizes revenues upon delivery of test reports. The fixed fees identified in contracts with laboratory partners change only if a pricing amendment is agreed upon between both parties. For cases in which there is no fixed price established with a laboratory partner, the Company then recognizes revenues from partner distributed tests on a cash basis. Certain of the Company's arrangements include multiple deliverables. For revenue arrangements with multiple deliverables, the Company evaluates each deliverable to determine whether it qualifies as a separate unit of accounting. This determination is based on whether the deliverable has "stand-alone value" to the customer and whether a general right of return exists. The consideration that is fixed or determinable is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. The consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. The Company uses judgment in identifying the deliverables in its arrangements, assessing whether each deliverable is a separate unit of accounting, and in determining the best estimate of selling price for certain deliverables. The Company also uses judgment in determining the period over which the deliverables are recognized in certain of its arrangements. Any amounts received that do not meet the criteria for revenue recognition are recorded as deferred revenue until such criteria are met. The Company receives royalty revenue through the licensing and the provisioning of services to support the use of the Company's proprietary technology with its customer. Royalty revenues are recognized when earned under the terms of the related agreements and are included in Other Revenues in the statements of operations. The Company recognizes revenue from the cloud-based distribution service offering. The Company grants customers licenses to use the Company’s proprietary intellectual properties and the cloud-based Natera software, and provides the other services to support the use of the Company's proprietary technology with its customers. Natera’s proprietary software is used in connection with the analysis of DNA sequence data in a manner yielding a result indicating the likely presence or absence of full or partial chromosomal abnormalities. The licensees do not have the right to possess Natera software, but rather are treated as software as a service. The revenues are recognized on an accrual basis (assuming all revenue recognition criteria are met) under the terms of the related agreements and are included in other revenues in the statements of operation.
Cost of Product Revenues	Cost of Product Revenues Cost of product revenues includes the cost of materials, direct labor of laboratory personnel, equipment and infrastructure expenses associated with processing blood and other samples, quality control analyses, and shipping charges to transport samples and specimens from ordering physicians, clinics or individuals. Infrastructure expenses include allocated facility and related occupancy costs. Costs associated with the performance of diagnostic services are recorded as tests are processed. Costs associated with grants received are reported in research and development expenses.
Research and Development	Research and Development The Company records research and development costs in the period incurred. Research and development costs consist of personnel costs, contract services, cost of materials utilized in performing tests, costs of clinical trials and allocated facilities and related overhead expenses.
Advertising Costs	Advertising Costs The Company expenses advertising costs as incurred. The Company incurred advertising costs of $1.1 million, $1.1 million and $0.4 million during 2015, 2014 and 2013, respectively.
Product Shipment Costs	Product Shipment Costs The Company expenses product shipment costs in cost of product revenues in the accompanying statements of operations. Shipping and handling costs for the years ended December 31, 2015, 2014 and 2013 were $7.0 million, $4.5 million and $2.0 million, respectively.
Income Taxes	Income Taxes Income taxes are recorded in accordance with Financial Accounting Standards Board ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Tax benefits are recognized when it is more likely than not that a tax position will be sustained during an audit. Deferred tax assets are reduced by a valuation allowance if current evidence indicates that it is considered more likely than not that these benefits will not be realized.
Stock Based Compensation	Stock ‑Based Compensation Stock ‑based compensation related to stock options granted to the Company’s employees is measured at the grant date based on the fair value of the award. The fair value is recognized as expense over the requisite service period, which is generally the vesting period of the respective awards. No compensation cost is recognized on stock options for employees who do not render the requisite service and therefore forfeit their rights to the stock options. The Company uses the Black ‑Scholes option ‑pricing model to estimate the fair value of its stock options. The Company accounts for stock options issued to non-employees based on the estimated fair value of the awards using the Black-Scholes option-pricing model. The measurement of stock-based compensation is subject to periodic adjustments as the underlying equity instruments vest, and the resulting change in value, if any, is recognized in the Company's statements of operations during the period that the related services are rendered. The Black-Scholes option-pricing model requires the input of the Company's expected stock price volatility, the expected life of the awards, a risk-free interest rate, and expected dividends. Determining these assumptions requires significant judgment. The expected term was based on the simplified method and where the Company did not qualify to use the simplified method, the Company used the lattice model, and the volatility rate was based on that of publicly traded companies in the DNA sequencing, diagnostics, or personalized medicine industries. When selecting the public companies in these industries to be used in the volatility calculation, companies were selected with comparable characteristics to the Company, including enterprise value and financial leverage. Companies were also selected with historical share price volatility sufficient to meet the expected life of the Company's stock options. The historical volatility data was computed using the daily closing prices for the selected companies' shares during the equivalent period of the calculated expected term of the Company's stock options. The expected life of the non-employee option grants was based on their remaining contractual life at the measurement date. The risk-free interest rate assumption was based on U.S. Treasury instruments with maturities that were consistent with the option's expected life. The expected dividend assumption was based on the Company's history and expectation of dividend payouts.
Warrants	Warrants The Company accounts for warrants to purchase shares of its common stock as a liability at fair value on the balance sheet date because the Company may be obligated to redeem these warrants at some point in the future. The warrants are subject to remeasurement at each balance sheet date, with changes in fair value recognized as a gain or loss from the changes in fair value of the warrants in the statements of operations. The Company will continue to adjust the liability for changes in fair value until such time that the warrants are converted or expire.
Capitalized Software Held for Internal Use	Capitalized Software Held for Internal Use We capitalize costs of software held for internal use during the application development stage of a project and amortize those costs over their estimated useful lives of three years. The net book value of capitalized software held for internal use was $0.8 million and $0 as of December 31, 2015 and 2014, respectively. Amortized expense for amounts previously capitalized for the year ended December 31, 2015 was $0.2 million.
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Comprehensive loss and its components encompass all changes in equity other than those with stockholders, and include net loss, unrealized gains and losses on available-for-sale marketable securities. As of December 31, 2015 and 2014, accumulated other comprehensive loss consisted of $1.4 million and nil of unrealized losses on available-for-sale marketable securities. There were no reclassifications out of accumulated other comprehensive loss during years ended December 31, 2015 and 2014
Property and Equipment	Property and Equipment Property and equipment, including purchased and internally developed software, are stated at cost. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, which are generally three years. Leasehold improvements are amortized using the straight-line method over the estimated useful lives of the assets or the remaining term of the lease, whichever is shorter. The Company periodically reviews the depreciable lives assigned to property and equipment placed in service and change the estimates of useful lives to reflect the results of such reviews. During April 2015, the Company increased the depreciable lives of certain sequencing and automation machinery equipment from three years to five years. The effect of this change in estimate for the year ended December 31, 2015 was a decrease in loss from operations and net loss of $1.7 million, respectively. The effect of this change in estimate was a decrease in net basic and diluted loss per share of $0.07 for the year ended December 31, 2015.
Inventory	Inventory Inventory is valued at the lower of the standard cost, which approximates actual cost, or market. Cost is determined using the first-in, first-out ("FIFO") method. Inventory consisted entirely of supplies, which are consumed when providing its test reports, and therefore does not maintain any finished goods inventory. The Company enters into inventory purchases and commitments so that it can meet future delivery schedules based on forecasted demand for its tests.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed below, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In August 2014, FASB issued Accounting Standards Update No. 2014 ‑15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (ASU 2014 ‑15). ASU 2014 ‑15 requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. In doing so, companies will have reduced diversity in the timing and content of footnote disclosures compared to footnote disclosures under today’s guidance. ASU 2014 ‑15 is effective for the Company in the first quarter of 2016 with early adoption permitted. The Company does not believe the impact of adopting ASU 2014 ‑15 on its financial statements will be significant. In May 2014, FASB issued Accounting Standards Update No. 2014 ‑09, Revenue from Contracts with Customers (ASU 2014 ‑09) to provide guidance on revenue recognition. ASU 2014 ‑09 requires a company to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under today’s guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. In August 2015, FASB issued ASU 2015-14, which defers the effective date of ASU 2014-09 for all entities by one year. ASU 2014-09 is effective for the Company in the first quarter of 2018. ASU 2014-09, as amended by ASU 2015-14, is effective for the Company in the fiscal year beginning after December 15, 2017, and interim periods within those years with early adoption permitted up to the first quarter of 2017. Upon adoption, ASU 2014 ‑09 can be applied retrospectively to all periods presented or only to the most current period presented with the cumulative effect of changes reflected in the opening balance of retained earnings in the most current period presented. The Company is currently evaluating the impact of adopting ASU 2014 ‑09 on its financial statements. In April 2015, FASB issued Accounting Standards Update No. 2015 ‑03, Interest—Imputation of Interest (Subtopic 835 ‑30): Simplifying the Presentation of Debt Issuance Costs (ASU 2015 ‑03). ASU 2015 ‑03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015 ‑03 is effective for the Company in the first quarter of 2016 with early adoption permitted. The Company does not believe the impact of adopting ASU 2015 ‑03 on its financial statements will be significant. In April 2015, FASB issued Accounting Standards Update No. 2015 ‑05, Intangibles—Goodwill and Other—Internal ‑Use Software (Subtopic 350 ‑40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement (ASU 2015 ‑05). ASU 2015 ‑05 provides guidance to clarify the customer’s accounting for fees paid in a cloud computing arrangement. ASU 2015 ‑05 is effective for the Company in the first quarter of 2016 with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2015 ‑05 on its financial statements. In July 2015, FASB issued Accounting Standards Update No. 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory (ASU 2015-11). ASU 2015-11 simplifies the subsequent measurement of inventory by replacing today’s lower of cost or market test with a lower of cost and net realizable value test. ASU 2015-11 is effective for the Company in the fiscal year beginning after December 15, 2016, and interim periods within those fiscal years. The Company is currently evaluating the impact of adopting ASU 2015 ‑11 on its financial statements. In November 2015, FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes , which simplifies the presentation of deferred taxes by requiring that deferred tax assets and liabilities be presented as noncurrent on the balance sheet. ASU 2015-17 is effective for the Company in the fiscal year beginning after December 15, 2016, and interim periods within those fiscal years. The Company is currently evaluating the impact of adopting ASU 2015 ‑17 on its financial statements. In February 2016, the FASB issued ASU No. 2016-2, Leases . ASU 2016-2 is aimed at making leasing activities more transparent and comparable, and requires substantially all leases be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. ASU 2016-2 is effective for the Company in the fiscal year beginning after December 15, 2018, and interim periods within those fiscal years with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2016-2 on its financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
Summary of financial assets and liabilities measured on recurring basis	December 31, 2015 December 31, 2014 Level I Level II Level III Total Level I Level II Level III Total (in thousands) Financial Assets: Money market deposits $ $ — $ — $ $ — $ — $ — $ — U.S. Treasury securities — — — — — — U.S. agency securities — — — — — — Municipal securities — — Total financial assets $ $ $ — $ $ — $ — $ — $ — Current Liabilities: Warrants $ — $ — $ $ $ — $ — $ $ Long-term Liabilities: Senior secured term loan $ — $ — $ — $ — $ — $ — $ $ Total financial liabilities $ — $ — $ $ $ — $ — $ $
Summary of quantitative information about inputs and valuation methodologies	Weighted Average Interest on Fair Value at Significant Discount Rate December 31, 2015 Valuation Methodology Unobservable Input (range, if applicable) (in thousands) (in thousands) —Warrants $ Black-Scholes Option Pricing Model Volatility %
Warrants
Rollforward of fair value determined by Level 3 inputs	Warrants 2015 2014 (in thousands) Beginning balance $ $ Warrants exercised — Change in fair value Ending balance $ $
Long-term Debt
Rollforward of fair value determined by Level 3 inputs	Term Loan 2015 2014 (in thousands) Beginning balance $ $ Change in fair value recognized in non-operating expense Loan payment — Ending balance $ — $

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2015
Financial Instruments
Schedule of available-for-sale securities	December 31, 2015 December 31, 2014 Amortized Cost Gross Unrealized Gain Gross Unrealized (Loss) Estimated Fair Value Amortized Cost Gross Unrealized Gain Gross Unrealized (Loss) Estimated Fair Value (in thousands) Money market deposits $ $ — $ — $ $ — $ — $ — $ — U.S. Treasury securities — — — — U.S. agency securities — — — — — Municipal securities Total $ $ $ $ $ — $ — $ — $ — Classified as: Cash equivalents $ $ — Short-term investments — Total $ $ —
Summarized portfolio of available-for-sale securities by contractual maturity	December 31, 2015 Amortized Cost Fair Value (in thousands) Less than one year $ $ Greater than one year but less than five years Total $ $

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2015
Balance Sheet Components
Schedule of allowance for doubtful accounts	December 31, December 31, 2015 2014 (in thousands) Beginning balance $ $ Provision for estimated bad debts Write offs Ending balance $ $
Schedule of property and equipment	December 31, December 31, Useful Life 2015 2014 (in thousands) Machinery and equipment 3 - 5 years $ $ Furniture and fixtures 3 years Computer equipment 3 years Capitalized software held for internal use 3 years — Leasehold improvements Life of lease Construction-in-process Less: Accumulated depreciation and amortization Total Property and Equipment, net $ $
Schedule of accrued compensation	December 31, December 31, 2015 2014 (in thousands) Accrued paid time off $ $ Accrued commissions Accrued bonuses Other accrued compensation Total accrued compensation $ $
Schedule of other accrued liabilities	December 31, December 31, 2015 2014 (in thousands) Accrued expenses $ $ Accrued rent Deferred lease obligation Accrued interest — Sales tax payable Total other accrued liabilities $ $

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies
Schedule of future minimum lease payments	Operating Leases (in thousands) Year ending December 31: 2016 $ 2017 2018 2019 2020 2021 and thereafter Total future minimum lease payments $

Stock_Based Compensation (Table

Stock‑Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of stock option activity	Outstanding Options Weighted- Weighted- Average Shares Average Remaining Aggregate Available for Number of Exercise Contractual Intrinsic (in thousands, except for contractual life and exercise price) Grant Shares Price Life Value (In years) Balance at December 31, 2014 $ 8.83 $ Additional shares authorized — Options granted $ Options exercised — $ Options forfeited $ Balance at December 31, 2015 $ 8.31 $ Exercisable at December 31, 2015 $ 5.31 $ Vested and expected to vest at December 31, 2015 $ 7.32 $
Summary of stock-based compensation expenses	Year ended December 31, 2015 2014 2013 Employee Non-Employee Total Employee Non-Employee Total Employee Non-Employee Total (in thousands) Cost of revenues $ $ $ $ $ $ $ $ $ Research and development Selling, general and administrative Total $ $ $ $ $ $ $ $
Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of assumptions used in valuation of fair value of employee stock options	Year ended December 31, 2015 2014 2013 Expected term 5.6 — 10.0 4.91 — 7.06 6.0 Expected volatility 69.7 % — 78.8 % 73.4 % — 87.0 % 63.7 % — 85.7 % Expected dividend rate % % % Risk-free interest rate 1.56 % — 2.32 % 1.65 % — 2.04 % 0.44 % — 2.86 %
Non-employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of assumptions used in valuation of fair value of employee stock options	Year ended December 31, 2015 2014 2013 Expected term 4.9 — 9.8 4.4 — 10.0 8.4 Expected volatility 70.2 % — 75.4 % 71.9 % — 80.2 % 75.6 % — 81.5 % Expected dividend rate % % % Risk-free interest rate 1.74 % — 2.24 % 1.41 % — 2.61 % 1.44 % — 2.51 %

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2015
Convertible Preferred Stock.
Schedule of convertible preferred stock	Shares Shares Issued and Liquidation Proceeds, net of Series Authorized Outstanding Amount Issuance Costs (in thousands) A-1 $ $ A B C D E F $ $

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Taxes
Schedule of effective tax rates differing from U.S. federal statutory rate	December 31, 2015 2014 (in thousands, except percentages) U.S. federal taxes (benefit) at statutory rate $ % $ % State tax expense % % Research and development credits % % Stock-based compensation % % Mark to market fair value adjustments % % Other nondeductible items % % Change in valuation allowance % % Provision for income taxes $ — — % $ %
Schedule of tax effects of temporary differences that give rise to significant portions of the deferred tax assets	December 31, 2015 2014 (in thousands) Deferred tax assets Net operating loss carryforwards $ $ Research and development tax credit carryforwards Reserves and accruals Stock-based compensation Total deferred tax assets before valuation allowance Less: valuation allowance Deferred tax liabilities Property and equipment Net deferred tax assets $ — $ —
Schedule of reconciliation of the beginning and ending amount of gross unrecognized tax benefits	December 31, 2015 2014 (in thousands) Balance at beginning of year $ $ Additions based on tax positions related to the current year Additions for tax positions of prior years — — Balance at end of year $ $

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Net Loss per Share
Basic and diluted net loss per common share	Year ended December 31, (in thousands, except per share data) 2015 2014 2013 Basic and diluted loss per share: Net loss $ $ $ Net loss attributable to common shares, basic and diluted Weighted-average common shares outstanding Less: weighted-average unvested common shares subject to repurchase Weighted-average number of shares used in computing net loss per share, basic and diluted Basic and diluted net loss per share $ $ $
Potentially dilutive shares not included in the calculation of dilutive EPS	Year ended December 31, 2015 2014 2013 Options to purchase common stock Warrants to purchase common stock Common stock subject to repurchase Convertible preferred stock —

Geographic Information (Tables)

Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2015
Geographic Information
Schedule of total revenue by geographic area	Year ended December 31, (in thousands) 2015 2014 2013 United States $ $ $ Americas, excluding U.S. Europe, Middle East, India, Africa Other Total $ $ $

Quarterly Financial Data (Table

Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Data
Schedule of quarterly financial data	Three months ended December 31, September 30, June 30, March 31, (in thousands, except per share data) 2015 Operating results: Total revenues $ $ $ $ Cost of product revenues Gross profit Other costs and expenses Interest expense and other income (expense), net Net loss Per share data: Net income - basic and diluted $ $ $ $ 2014 Operating results: Total revenues $ $ $ $ Cost of product revenues Gross profit Other costs and expenses Interest expense and other income (expense), net Net income (loss) Per share data: Net income - basic $ - $ $ $ Net income - diluted -

Description of Business (Detail

Description of Business (Details) $ / shares in Units, $ in Millions	Jun. 19, 2015	Jul. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2015segment$ / sharesshares
Number of operating segment | segment			1
Stock split conversion	0.6135
Common stock
Initial public offering (in shares) | shares			10,900,000
Initial public offering price (in dollars per share) | $ / shares			$ 11.57
IPO | Common stock
Initial public offering (in shares) | shares		10,900,000
Initial public offering price (in dollars per share) | $ / shares		$ 18
Proceeds from initial public offering, net of offering costs | $		$ 178.5

Summary of Significant Accoun37

Summary of Significant Accounting Policies (Additional Capital) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Policies
Net (loss) income	$ (22,960)	$ (17,630)	$ (19,681)	$ (10,004)	$ 1,254	$ 3,724	$ (514)	$ (9,616)	$ (70,275)	$ (5,152)	$ (37,110)
Accumulated deficit	250,083				179,808				250,083	179,808
Cash and cash equivalents	28,947				87,176				28,947	87,176	$ 30,496	$ 5,747
Short-term investments	201,586								201,586
Restricted cash
Restricted cash, current portion	901				503				901	503
Restricted cash, long term portion	683				$ 808				683	$ 808
Corporate Headquarters Lease
Restricted cash
Restricted cash, current portion	800								800
Restricted cash, long term portion	300								300
Cancellation of Service
Restricted cash
Restricted cash, current portion	100								100
Credit Card
Restricted cash
Restricted cash, long term portion	$ 400								$ 400

Summary of Significant Accoun38

Summary of Significant Accounting Policies (Concentration) (Details) - customer	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Sales | Customer
Risk and Uncertainties
Number of customers	0	0	2
Sales | Customer | Quest
Risk and Uncertainties
Concentration risk (as a percent)			16.00%
Sales | Customer | Progenity
Risk and Uncertainties
Concentration risk (as a percent)			12.00%
Accounts Receivable | Credit
Risk and Uncertainties
Number of customers	0	0	2
Accounts Receivable | Credit | Customer one
Risk and Uncertainties
Concentration risk (as a percent)			37.00%
Accounts Receivable | Credit | Customer two
Risk and Uncertainties
Concentration risk (as a percent)			18.00%

Summary of Significant Accoun39

Summary of Significant Accounting Policies (Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary of Significant Accounting Policies
Advertising costs	$ 1,100	$ 1,100	$ 400
Shipping and handling costs	7,000	4,500	$ 2,000
Capitalized software	800	0
Capitalized software expense	200
Accumulated other comprehensive loss	1,416
Reclassifications out of accumulated other comprehensive loss	$ 0	$ 0

Summary of Significant Accoun40

Summary of Significant Accounting Policies (Property) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Apr. 30, 2015	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property and Equipment
Estimated useful life										P3Y
Gain (loss) from operations										$ (59,838)	$ 665	$ (25,268)
Net loss		$ 22,960	$ 17,630	$ 19,681	$ 10,004	$ (1,254)	$ (3,724)	$ 514	$ 9,616	$ 70,275	$ 5,152	$ 37,110
Basic and diluted net loss per share (in dollars per share)		$ (0.47)	$ (0.39)	$ (3.58)	$ (1.89)					$ (2.68)	$ (1.07)	$ (9.66)
Machinery and equipment | Change to estimated useful life
Property and Equipment
Estimated useful life	P3Y									P5Y
Net loss										$ 1,700
Basic and diluted net loss per share (in dollars per share)										$ (0.07)

Fair Value Measurements (Hierar

Fair Value Measurements (Hierarchy) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Transfers between Levels 1 and 2
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	$ 0	$ 0
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	0	0
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount	0	0
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount	0	0
Transfers into and out of Level 3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3	0	0
Recurring
Financial Assets:
Total financial assets	207,552,000
Current Liabilities:
Warrants	3,649,000	2,232,000
Long‑term Liabilities:
Senior secured term loan		20,964,000
Total financial liabilities	3,649,000	23,196,000
Recurring | Money market deposits
Financial Assets:
Total financial assets	5,966,000
Recurring | U.S. Treasury securities
Financial Assets:
Total financial assets	103,813,000
Recurring | U.S. agency securities
Financial Assets:
Total financial assets	78,853,000
Recurring | Municipal securities
Financial Assets:
Total financial assets	18,920,000
Recurring | Level 1
Financial Assets:
Total financial assets	109,779,000
Recurring | Level 1 | Money market deposits
Financial Assets:
Total financial assets	5,966,000
Recurring | Level 1 | U.S. Treasury securities
Financial Assets:
Total financial assets	103,813,000
Recurring | Level 2
Financial Assets:
Total financial assets	97,773,000
Recurring | Level 2 | U.S. agency securities
Financial Assets:
Total financial assets	78,853,000
Recurring | Level 2 | Municipal securities
Financial Assets:
Total financial assets	18,920,000
Recurring | Level 3
Current Liabilities:
Warrants	3,649,000	2,232,000
Long‑term Liabilities:
Senior secured term loan		20,964,000
Total financial liabilities	$ 3,649,000	$ 23,196,000

Fair Value Measurements (Level

Fair Value Measurements (Level III) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Loss on debt extinguishment		$ (7,313)
Secured Loan Arrangement
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Loss on debt extinguishment	$ (2,000)	2,000
Royalty Agreement
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Loss on debt extinguishment		5,300
Long-term Debt | Secured Loan Arrangement
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		20,964	$ 21,082
Settled		(20,000)
Ending balance			20,964
Long-term Debt | Non‑Operating Expense | Secured Loan Arrangement
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in fair value		(964)	(118)
Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		2,232	568
Change in fair value		1,657	1,664
Settled		(240)
Ending balance		$ 3,649	$ 2,232

Fair Value Measurements (Assump

Fair Value Measurements (Assumptions) (Details) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2015USD ($)company	Sep. 30, 2015company	Dec. 31, 2015USD ($)
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Volatility, basket of companies | company	4	15
Warrants
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Volatility (as a percent)			79.60%
Warrant valuation increase	$ 200
Warrants | Level 3
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Warrants	$ 3,649		$ 3,649

Financial Instruments (Details)

Financial Instruments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)position
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Estimated Fair Value	$ 201,586
Interest income	$ 300
Number of investments, unrealized loss position | position	73
Amortized Cost
Less than one year	$ 55,128
Greater than one year but less than five years	153,840
Total	208,968
Fair Value
Less than one year	55,010
Greater than one year but less than five years	152,542
Total	207,552
Available-for-sale securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	208,968
Unrealized Gain	3
Unrealized Loss	(1,419)
Estimated Fair Value	207,552
Money market deposits
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	5,966
Estimated Fair Value	5,966
U.S. Treasury securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	104,537
Unrealized Gain	1
Unrealized Loss	(725)
Estimated Fair Value	103,813
U.S. agency securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	79,491
Unrealized Loss	(638)
Estimated Fair Value	78,853
Municipal securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	18,974
Unrealized Gain	2
Unrealized Loss	(56)
Estimated Fair Value	18,920
Cash equivalents | Available-for-sale securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Estimated Fair Value	5,966
Short-term investments | Available-for-sale securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Estimated Fair Value	$ 201,586

Balance Sheet Components (Allow

Balance Sheet Components (Allowance for Doubtful Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for doubtful accounts
Beginning balance	$ 527	$ 508
Provision for estimated bad debts	529	349	$ 527
Write offs	(85)	(330)
Ending balance	$ 971	$ 527	$ 508

Balance Sheet Components (Prope

Balance Sheet Components (Property) (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 31, 2016	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015
Property and Equipment, net
Property and equipment, gross		$ 26,500,000	$ 26,500,000	$ 24,168,000
Less: Accumulated depreciation and amortization		(13,790,000)	(13,790,000)	(9,594,000)
Total Property and Equipment, net		12,710,000	12,710,000	14,574,000
Impairment of assets			1,557,000
Proceeds from sale of impaired machinery and equipment			463,000	15,000
Equipment pledged					$ 0
Machinery and equipment
Property and Equipment, net
Property and equipment, gross		20,670,000	20,670,000	18,632,000
Impairment of assets			1,000,000
Proceeds from sale of impaired machinery and equipment		500,000
Asset held for sale		200,000	200,000
Machinery and equipment | Subsequent Event
Property and Equipment, net
Proceeds from sale of impaired machinery and equipment	$ 200,000
Furniture and fixtures
Property and Equipment, net
Property and equipment, gross		217,000	$ 217,000	217,000
Useful Life			3 years
Computer equipment
Property and Equipment, net
Property and equipment, gross		911,000	$ 911,000	700,000
Useful Life			3 years
Capitalized software held for internal use
Property and Equipment, net
Property and equipment, gross		1,037,000	$ 1,037,000
Useful Life			3 years
Leasehold improvements
Property and Equipment, net
Property and equipment, gross		1,686,000	$ 1,686,000	1,036,000
Construction-in-process
Property and Equipment, net
Property and equipment, gross		$ 1,979,000	$ 1,979,000	$ 3,583,000
Minimum | Machinery and equipment
Property and Equipment, net
Useful Life			3 years
Maximum | Machinery and equipment
Property and Equipment, net
Useful Life			5 years

Balance Sheet Components (Compe

Balance Sheet Components (Compensation) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Balance Sheet Components
Accrued paid time off	$ 2,024	$ 1,577
Accrued commissions	3,691	2,651
Accrued bonuses	1,348	1,141
Other accrued compensation	1,489	611
Total accrued compensation	$ 8,552	$ 5,980

Balance Sheet Components (Accur

Balance Sheet Components (Accured liab) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Balance Sheet Components
Accrued expenses	$ 17,870	$ 8,560
Accrued rent	450	551
Deferred lease obligation	42	99
Accrued interest		764
Sales tax payable	346	367
Total other accrued liabilities	$ 18,708	$ 10,341

Commitments and Contingencies49

Commitments and Contingencies (Details)	1 Months Ended			12 Months Ended
	Oct. 31, 2015USD ($)ft²item	Sep. 30, 2015USD ($)	Apr. 30, 2015USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Mar. 21, 2014USD ($)	Jan. 31, 2013USD ($)
Future minimum lease payments
2,016				$ 3,212,000
2,017				5,442,000
2,018				5,976,000
2,019				6,140,000
2,020				6,304,000
2021 and thereafter				25,922,000
Total future minimum lease payment				52,996,000
Rent expense				$ 2,700,000	$ 1,500,000	$ 1,300,000
Corporate Headquarters Lease
Operating Leases
Restricted cash							$ 300,000	$ 800,000
Monthly base rent	$ 200,000
Security deposit	500,000
Allowance for leasehold improvements	$ 400,000
Number of office spaces | item	2
Office space | ft²	88,000
Renewal term of lease	5 years
Redwood City Lease
Operating Leases
Monthly base rent			$ 100,000
Security deposit			$ 100,000
Austin TX, Long-term Lease
Operating Leases
Term of lease		132 months
Monthly base rent		$ 100,000
Security deposit		400,000
Maximum monthly base rent after escalation		200,000
Allowance for leasehold improvements		$ 7,800,000
Austin TX, Short-term Lease
Operating Leases
Term of lease	1 year
Monthly base rent	$ 12,900
Security deposit	12,900
Maximum | Corporate Headquarters Lease
Operating Leases
Monthly base rent	$ 400,000

Commitments and Contingencies50

Commitments and Contingencies (Legal) (Details) $ in Millions	Feb. 17, 2016	Jun. 02, 2015USD ($)	Aug. 31, 2015USD ($)	Nov. 30, 2013item	Mar. 31, 2016lawsuit	Dec. 31, 2015USD ($)	Jan. 31, 2015USD ($)
Inventory Material
Other commitments
Purchase commitment						$ 12.2
Tests
Other commitments
Purchase commitment							$ 5.1
Supplier One | Inventory Material
Other commitments
Purchase commitment						12.2
Supplier, Aggregate of Other | Inventory Material
Other commitments
Purchase commitment						$ 1.5
Patent infringement
Other commitments
Number of judgements appealed | item				3
Third-party payer
Other commitments
Amount sought		$ 1.9
Settlement amount			$ 1.2
Subsequent Event | IPO claims
Other commitments
Shareholders (as a percent)	5.00%
Number of purported class action lawsuits filed | lawsuit					2

Stock_Based Compensation (Detai

Stock‑Based Compensation (Details)	1 Months Ended	12 Months Ended
	Jun. 30, 2015USD ($)periodshares	Dec. 31, 2015USD ($)$ / sharesshares
2015 Plan
Stock Based Compensation
Shares reserved for issuance	3,451,495	3,743,382
Shares reserved for issuance as a proportion common stock outstanding (as a percent)	4.00%
Automatic termination of plan, term		10 years
2015 Plan | Non-employee directors
Stock Based Compensation
Aggregate grant date fair value of awards granted, annual ceiling limitation amount | $	$ 500,000
2015 Plan | Newly appointed non-employee directors
Stock Based Compensation
Aggregate grant date fair value of awards granted, annual ceiling limitation amount | $	$ 1,000,000
2015 Plan | Minimum
Stock Based Compensation
Shares reserved for issuance	3,500,000
2007 Plan
Stock Based Compensation
Shares reserved for issuance		15,258,947
Automatic termination of plan, term		10 years
2015 Employee Stock Purchase Plan
Stock Based Compensation
Shares reserved for issuance	893,548
Shares reserved for issuance as a proportion common stock outstanding (as a percent)	1.00%
Price in relation to fair market value of common stock on the date of grant, lower range limit (as a percent)	85.00%
Maximum amount of award or purchase during a calendar year | $	$ 25,000
Requisite service requirement (in hours per week)	20 hours
Requisite service requirement (in months per year)	5 months
Maximum offering period, term	27 months
Number of expected offering periods each year | period	2
Offering period, expected term	6 months
Maximum employee contribution of employee's cash compensation (as a percent)	15.00%
Maximum aggregate amount of shares a participant may receive during the fiscal year | $	$ 5,000
2015 Employee Stock Purchase Plan | Minimum
Stock Based Compensation
Shares reserved for issuance	880,000
Employee and non-employee stock options | 2015 Plan
Stock Based Compensation
Price in relation to fair market value of common stock on the date of grant, lower range limit (as a percent)	100.00%
Vesting period	4 years
Expiration period	10 years
Maximum number of shares a participant may receive during the fiscal year (in shares)	1,725,000
Additional number of shares a new employee may receive during initial fiscal year of employment (in shares)	350,000
Employee and non-employee stock options | 2007 Plan
Stock Based Compensation
Price in relation to fair market value of common stock on the date of grant, lower range limit (as a percent)		100.00%
Vesting period		4 years
Expiration period		10 years
Stock options, exercise price range, number outstanding (in shares)		8,621,395
Stock options, exercise price range, lower range limit (in dollars per share) | $ / shares		$ 0.0065
Stock options, exercise price range, upper range limit (in dollars per share) | $ / shares		12.8501
Stock options, exercise price range, weighted-average exercise price (in dollars per share) | $ / shares		$ 3.27
Shares exercised and unvested		1,300,000
Period after Market Stand-off repurchase right expires		210 days
Accelerated stock-based compensation expense | $		$ 1,300,000
Stock appreciation rights | 2015 Plan
Stock Based Compensation
Price in relation to fair market value of common stock on the date of grant, lower range limit (as a percent)	100.00%
Vesting period	4 years
Expiration period	10 years
Maximum number of shares a participant may receive during the fiscal year (in shares)	1,725,000
Additional number of shares a new employee may receive during initial fiscal year of employment (in shares)	350,000
Restricted shares and stock Units | 2015 Plan
Stock Based Compensation
Maximum number of shares a participant may receive during the fiscal year (in shares)	1,500,000
Additional number of shares a new employee may receive during initial fiscal year of employment (in shares)	300,000
Performance awards | 2015 Plan
Stock Based Compensation
Maximum amount of award or purchase during a calendar year | $	$ 5,000,000

Stock_Based Compensation (Optio

Stock‑Based Compensation (Options) (Details) - Employee and non-employee stock options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Based Compensation
Shares available for grant, beginning balance	294
Additional shares authorized	4,985
Options granted (in shares)	(2,181)
Options forfeited (in shares)	645
Shares available for grant, end balance	3,743	294
Number of shares
Outstanding, beginning balance (in shares)	8,463
Options granted (in shares)	2,181
Options exercised (in shares)	(683)
Options forfeited (in shares)	(645)
Outstanding, end balance (in shares)	9,316	8,463
Exercisable (in shares)	5,602
Vested and expected to vest (in shares)	8,414
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per shares)	$ 2.28
Granted (in dollars per share)	10.16
Exercised (in dollars per share)	1.72
Forfeited (in dollars per share)	5.25
Outstanding, end balance (in dollars per shares)	3.96	$ 2.28
Exercisable (in dollars per share)	1.90
Vested and expected to vest (in dollars per share)	$ 3.72
Additional disclosures
Weighted average contractual term, options outstanding	8 years 3 months 22 days	8 years 9 months 29 days
Exercisable (in years)	5 years 3 months 22 days
Vested and expected to vest (in years)	7 years 3 months 26 days
Aggregate intrinsic value, options outstanding	$ 63,713	$ 43,659
Aggregate intrinsic value, options exercisable	49,880
Aggregate intrinsic value, vested and expected to vest	59,529
Aggregate intrinsic value, options exercised	6,900	1,200	$ 700
Fair value, options vested	$ 4,500	$ 4,100	$ 1,000
Weighted-average grant date fair value, options granted	$ 7.29	$ 3.28	$ 0.99

Stock_Based Compensation (CompE

Stock‑Based Compensation (CompExp) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee and non-employee stock options
Stock based compensation expense
Stock based compensation expense	$ 7,326	$ 5,157	$ 1,657
Unrecognized compensation expense	$ 14,700
Unrecognized compensation expense recognized over weighted average period	1 year 11 months 16 days
Employee and non-employee stock options | Cost of revenues
Stock based compensation expense
Stock based compensation expense	$ 592	291	62
Employee and non-employee stock options | Research and development
Stock based compensation expense
Stock based compensation expense	1,575	1,593	616
Employee and non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock based compensation expense	5,159	3,273	979
Employee stock options
Stock based compensation expense
Stock based compensation expense	6,910	5,005	1,637
Employee stock options | Cost of revenues
Stock based compensation expense
Stock based compensation expense	351	262	55
Employee stock options | Research and development
Stock based compensation expense
Stock based compensation expense	1,566	1,563	612
Employee stock options | Selling, general and administrative
Stock based compensation expense
Stock based compensation expense	4,993	3,180	970
Non-employee stock options
Stock based compensation expense
Stock based compensation expense	416	152	20
Non-employee stock options | Cost of revenues
Stock based compensation expense
Stock based compensation expense	241	29	7
Non-employee stock options | Research and development
Stock based compensation expense
Stock based compensation expense	9	30	4
Non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock based compensation expense	$ 166	$ 93	$ 9

Stock_Based Compensation (Assum

Stock‑Based Compensation (Assumptions) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee and non-employee stock options
Stock Based Compensation
Options granted (in shares)	2,181
Employee stock options
Valuation of Stock Option Grants to Employees
Expected term			6 years
Expected volatility, minimum	69.70%	73.40%	63.70%
Expected volatility, maximum	78.80%	87.00%	85.70%
Expected dividend rate	0.00%	0.00%	0.00%
Risk‑free interest rate, minimum	1.56%	1.65%	0.44%
Risk‑free interest rate, maximum	2.32%	2.04%	2.86%
Employee stock options | Minimum
Valuation of Stock Option Grants to Employees
Expected term	5 years 7 months 6 days	4 years 10 months 28 days
Employee stock options | Maximum
Valuation of Stock Option Grants to Employees
Expected term	10 years	7 years 22 days
Non-employee stock options
Stock Based Compensation
Options granted (in shares)	200
Options unvested (in shares)	100
Valuation of Stock Option Grants to Employees
Expected term			8 years 4 months 24 days
Expected volatility, minimum	70.20%	71.90%	75.60%
Expected volatility, maximum	75.40%	80.20%	81.50%
Expected dividend rate	0.00%	0.00%	0.00%
Risk‑free interest rate, minimum	1.74%	1.41%	1.44%
Risk‑free interest rate, maximum	2.24%	2.61%	2.51%
Non-employee stock options | Minimum
Valuation of Stock Option Grants to Employees
Expected term	4 years 10 months 24 days	4 years 4 months 24 days
Non-employee stock options | Maximum
Valuation of Stock Option Grants to Employees
Expected term	9 years 9 months 18 days	10 years

Debt (Details)

Debt (Details) $ / shares in Units, $ in Thousands	1 Months Ended					12 Months Ended
	Nov. 30, 2015USD ($)	Oct. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2014USD ($)item	Apr. 30, 2013USD ($)$ / sharesshares	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)item	Dec. 31, 2013USD ($)	Apr. 30, 2014$ / shares	Dec. 31, 2007$ / shares
Debt Instrument [Line Items]
Interest expense						$ 3,505	$ 4,219	$ 1,873
Royalty due						1,800
Exercise price of warrants (in dollars per share) | $ / shares										$ 0.0978
Prepayment penalty						7,313
Repayments of equipment financing						$ 5,850	$ 2,480	$ 475
Secured Loan Arrangement
Debt Instrument [Line Items]
Effective interest rate (as a percent)				19.80%		20.90%	19.80%	12.60%
Number of shares of common stock that may be called by warrants | shares					376,691
Exercise price of warrants (in dollars per share) | $ / shares					$ 2.3229				$ 2.3229
Prepayment premium (as a percent)		10.00%			10.00%
Debt paid off		$ 20,000
Amount paid to extinguish debt		28,000
Prepayment penalty		2,000				$ (2,000)
Credit Agreement
Debt Instrument [Line Items]
Borrowing capacity					$ 40,000
Borrowings					$ 20,000
Base interest rate (as a percent)					1.00%
Spread on base interest rate (as a percent)					8.00%
Interest rate floor (as a percent)					9.00%
Interest expense						1,400	$ 1,800	$ 1,300
Minimum liquidity required under debt covenants					$ 5,000
Royalty Agreement
Debt Instrument [Line Items]
Royalty payment percentage owed on fiscal year revenues up to threshold					1.00%
Revenue threshold amount for determination of royalty payment percentage					$ 50,000
Royalty payment percentage owed on fiscal year revenues in excess of threshold					1.50%
Interest expense		6,000				7,100	$ 2,200	$ 500
Prepayment penalty						$ (5,300)
Line Of Credit-UBS
Debt Instrument [Line Items]
Borrowing capacity			$ 50,000
Borrowings	$ 10,000	$ 32,000
Effective interest rate (as a percent)	0.85%	0.84%
Line Of Credit-UBS | 30-day LIBOR
Debt Instrument [Line Items]
Spread on variable rate (as a percent)			0.65%
Equipment Financing Facility
Debt Instrument [Line Items]
Borrowing capacity					$ 5,000
Borrowings				$ 5,900
Effective interest rate (as a percent)				6.35%	7.35%		6.35%
Number of payment installments | item				30			30
Repayments of equipment financing			$ 4,100
Equipment Financing Facility | 30-day LIBOR
Debt Instrument [Line Items]
Spread on reference rate (as a percent)					2.50%
Spread on variable rate (as a percent)					4.10%
Equipment Financing Facility | Prime
Debt Instrument [Line Items]
Spread on reference rate (as a percent)				3.10%

Warrants (Details)

Warrants (Details)	Nov. 20, 2014$ / sharesshares	Jul. 31, 2015shares	Dec. 31, 2015$ / sharesshares	Apr. 30, 2014$ / sharesshares	Apr. 30, 2013$ / shares	Dec. 31, 2009$ / sharesshares	Dec. 31, 2007$ / sharesshares
Class of Stock [Line Items]
Warrants outstanding (in shares)							24,538
Warrants exercise price (in dollars per share) | $ / shares							$ 0.0978
Secured Loan Arrangement
Class of Stock [Line Items]
Warrants outstanding (in shares)				376,691
Warrants exercise price (in dollars per share) | $ / shares				$ 2.3229	$ 2.3229
B
Class of Stock [Line Items]
Warrants outstanding (in shares)						33,742
Warrants exercise price (in dollars per share) | $ / shares						$ 1.8908
E
Class of Stock [Line Items]
Warrants outstanding (in shares)	429,440
Warrants exercise price (in dollars per share) | $ / shares	$ 0.0163
Liquidation preference change (as a percent)	2
Common stock
Class of Stock [Line Items]
Closing price (in dollars per share) | $ / shares			$ 11.57
Conversion into common shares (in shares)			31,397,000
Common stock | B
Class of Stock [Line Items]
Common stock issued for each warrant (in shares)		1	28,227
Common stock | E
Class of Stock [Line Items]
Conversion into common shares (in shares)		429,042

Convertible Preferred Stock (De

Convertible Preferred Stock (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2014USD ($)director$ / sharesshares	Dec. 31, 2015$ / sharesshares	Jul. 31, 2015shares	Dec. 31, 2013$ / shares
Stock
Convertible preferred stock, shares outstanding | shares	31,397,000		31,397,221
Common stock, shares authorized | shares	82,000,000	750,000,000
Preferred stock, shares authorized | shares	50,000,000	50,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Liquidation Amount	$ 133,757
Proceeds, net of Issuance Costs	240,612
Minimum IPO price for automatic conversion	$ 40,000
Minimum holder consenting to automatic conversion (as a percent)	70.00%
Maximum recapitalization for automatic conversion	$ 100,000
Convertible preferred stock
Stock
Convertible preferred stock, shares outstanding | shares	31,397,000
Preferred stock, shares authorized | shares	51,233,000
Liquidation Amount	$ 133,757
Proceeds, net of Issuance Costs	$ 240,612
A1
Stock
Convertible preferred stock, shares outstanding | shares	3,067,000
Preferred stock, shares authorized | shares	5,000,000
Liquidation Amount	$ 20
Proceeds, net of Issuance Costs	$ 20
Convertible preferred stock conversion numerator (in dollars per share) | $ / shares	$ 0.0065
Convertible preferred stock conversion denominator (in dollars per share) | $ / shares	$ 0.0065
Dividend rate (as a percent)	0.0005%
A
Stock
Convertible preferred stock, shares outstanding | shares	5,014,000
Preferred stock, shares authorized | shares	8,173,000
Liquidation Amount	$ 4,005
Proceeds, net of Issuance Costs	$ 3,927
Convertible preferred stock conversion numerator (in dollars per share) | $ / shares	$ 0.7987
Convertible preferred stock conversion denominator (in dollars per share) | $ / shares	$ 0.7987
Dividend rate (as a percent)	0.0639%
B
Stock
Convertible preferred stock, shares outstanding | shares	3,491,000
Preferred stock, shares authorized | shares	5,745,000
Liquidation Amount	$ 6,600
Proceeds, net of Issuance Costs	$ 6,569
Convertible preferred stock conversion numerator (in dollars per share) | $ / shares	$ 1.8908
Convertible preferred stock conversion denominator (in dollars per share) | $ / shares	$ 1.8908
Dividend rate (as a percent)	0.1513%
C
Stock
Convertible preferred stock, shares outstanding | shares	5,485,000
Preferred stock, shares authorized | shares	8,941,000
Liquidation Amount	$ 12,160
Proceeds, net of Issuance Costs	$ 58,876
Convertible preferred stock conversion numerator (in dollars per share) | $ / shares	$ 2.2168
Convertible preferred stock conversion denominator (in dollars per share) | $ / shares	$ 2.2168
Number of directors electable | director	1
Number of directors elected | director	0
Dividend rate (as a percent)	0.1773%
D
Stock
Convertible preferred stock, shares outstanding | shares	4,107,000
Preferred stock, shares authorized | shares	6,694,000
Liquidation Amount	$ 20,047
Proceeds, net of Issuance Costs	$ 80,788
Convertible preferred stock conversion numerator (in dollars per share) | $ / shares	$ 4.8819
Convertible preferred stock conversion denominator (in dollars per share) | $ / shares	$ 4.8819
Dividend rate (as a percent)	0.3911%
E
Stock
Convertible preferred stock, shares outstanding | shares	5,884,000
Preferred stock, shares authorized | shares	9,592,000
Liquidation Amount	$ 35,425
Proceeds, net of Issuance Costs	$ 35,019
Convertible preferred stock conversion numerator (in dollars per share) | $ / shares	$ 6.0199			$ 6.02
Convertible preferred stock conversion denominator (in dollars per share) | $ / shares	$ 6.0199
Dividend rate (as a percent)	0.4817%
F
Stock
Convertible preferred stock, shares outstanding | shares	4,349,000
Preferred stock, shares authorized | shares	7,088,000
Liquidation Amount	$ 55,500
Proceeds, net of Issuance Costs	$ 55,413
Convertible preferred stock conversion numerator (in dollars per share) | $ / shares	$ 12.7629
Convertible preferred stock conversion denominator (in dollars per share) | $ / shares	$ 12.7629
Dividend rate (as a percent)	1.021%
A and B
Stock
Number of directors electable | director	2

Common Stock (Details)

Common Stock (Details) shares in Thousands	Jun. 19, 2015	Dec. 31, 2015item$ / sharesshares	Dec. 31, 2014$ / sharesshares
Common Stock.
Authorized common stock (in shares)		750,000	82,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001	$ 0.0001
Common stock outstanding (in shares)		50,346	6,879
Number of votes | item		1
Stock split conversion	0.6135

Income Taxes (Effective Tax Rat

Income Taxes (Effective Tax Rates) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Effective tax rates differing from U.S. federal statutory rate
U.S. Federal taxes (Benefit) at statutory rate	$ (24,375)	$ (1,747)
State tax expense	(2,428)	(294)
Research and development credits	(751)	(530)
Stock-based compensation	1,683	755
Mark to market fair value adjustments	504	566
Other nondeductible items	841	414
Change in valuation allowance	$ 24,526	851
Provision for income taxes		$ 15
U.S. Federal taxes (Benefit) at statutory rate (as a percent)	(34.00%)	(34.00%)
State tax expense (as a percent)	(3.39%)	(5.72%)
Research and development credits (as a percent)	(1.05%)	(10.32%)
Stock-based compensation (as a percent)	2.35%	14.70%
Mark to market fair value adjustments (as a percent)	0.70%	11.01%
Other nondeductible items (as a percent)	1.17%	8.05%
Change in valuation allowance (as a percent)	34.21%	16.57%
Provision for income taxes (as a percent)		0.29%
State income tax expense		$ 15

Income Taxes (Deferred Tax Asse

Income Taxes (Deferred Tax Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes
Valuation allowance increase	$ 24,500	$ 900	$ 10,800
Deferred tax assets
Net operating loss carryforwards	41,451	21,587
Research and development tax credit carryforwards	4,794	2,696
Reserves and accruals	3,108	1,717
Stock based compensation	2,206	1,505
Total deferred tax assets before valuation allowance	51,559	27,505
Less: valuation allowance	(51,153)	(26,627)
Deferred tax assets, net	406	878
Deferred tax liabilities
Property and equipment	$ (406)	$ (878)

Income Taxes (Net Operating Los

Income Taxes (Net Operating Loss Carryforwards) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Operating Loss Carryforwards [Line Items]
Excess tax benefits from employee stock option exercises, equity increase	$ 1.4
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	114.5
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 73.2

Income Taxes (Tax Credit Carryf

Income Taxes (Tax Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2015USD ($)
Tax Credit Carryforward [Line Items]
Taxable income required for full realization of deferred tax assets	$ 138.8
Federal | Research and development tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	4.6
State | Research and development tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 3.4

Income Taxes (Unrecognized Tax

Income Taxes (Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Interest and penalties accrued	$ 0
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Balance at beginning of year	1,360	$ 898
Additions based on tax positions related to the current year	1,045	462
Balance at end of year	2,405	1,360
Research and development tax credit carryforward
Unrecognized tax benefits increased	$ 1,000	$ 500

Related_Party Transactions (Det

Related‑Party Transactions (Details) - USD ($)	1 Months Ended	12 Months Ended
	Apr. 30, 2012	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Dr Rabinowitz | Apartment rent
Related‑Party Transactions
Related party cost expensed		$ 9,500	$ 22,800	$ 22,642
Dr Rabinowitz | Notes Receivable from Officers
Related‑Party Transactions
Note receivable	$ 154,000
Note receivable interest rate (as a percent)	1.15%
Mr Sheena | Notes Receivable from Officers
Related‑Party Transactions
Note receivable	$ 38,280
Note receivable interest rate (as a percent)	1.15%

Net Loss per Share (EPS) (Detai

Net Loss per Share (EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Basic and diluted loss per share:
Net loss	$ (22,960)	$ (17,630)	$ (19,681)	$ (10,004)	$ 1,254	$ 3,724	$ (514)	$ (9,616)	$ (70,275)	$ (5,152)	$ (37,110)
Net loss attributable to common shares, basic and diluted									$ (70,275)	$ (5,152)	$ (37,110)
Weighted-average common shares outstanding									27,687	6,670	6,093
Less: weighted-average unvested common shares subject to repurchase									(1,483)	(1,870)	(2,252)
Weighted-average number of shares used in computing net loss per share, basic and diluted									26,204	4,800	3,841
Basic and diluted net loss per share (in dollars per share)	$ (0.47)	$ (0.39)	$ (3.58)	$ (1.89)					$ (2.68)	$ (1.07)	$ (9.66)

Net Loss per Share (AntiDil) (D

Net Loss per Share (AntiDil) (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS	11,000	42,401	33,941
Employee and non-employee stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS	9,316	8,450	4,406
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS	377	864	410
Common stock subject to repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS	1,307	1,690	2,077
Redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS		31,397	27,048

Geographic Information (Details

Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 52,912	$ 44,921	$ 45,087	$ 47,435	$ 49,884	$ 46,274	$ 35,836	$ 27,295	$ 190,355	$ 159,289	$ 55,171
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									164,952	136,478	48,263
Americas, excluding U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									4,552	4,883	1,402
Europe, Middle East, India, Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									15,437	13,098	4,275
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 5,414	$ 4,830	$ 1,231

Quarterly Financial Data (Detai

Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating results:
Total revenues	$ 52,912	$ 44,921	$ 45,087	$ 47,435	$ 49,884	$ 46,274	$ 35,836	$ 27,295	$ 190,355	$ 159,289	$ 55,171
Cost of product revenues	31,814	30,456	25,732	24,843	22,662	20,820	19,014	15,900	112,845	78,396	37,275
Gross profit	21,098	14,465	19,355	22,592	27,222	25,454	16,822	11,395
Other costs and expenses	38,446	35,206	34,827	28,869	22,849	20,675	18,027	18,677
Interest expense and other income (expense), net	(5,612)	3,111	(4,209)	(3,727)	(3,119)	(1,055)	691	(2,334)
Net (loss)	$ (22,960)	$ (17,630)	$ (19,681)	$ (10,004)	$ 1,254	$ 3,724	$ (514)	$ (9,616)	$ (70,275)	$ (5,152)	$ (37,110)
Per share data:
Net income - basic and diluted (in dollars per share)	$ (0.47)	$ (0.39)	$ (3.58)	$ (1.89)					$ (2.68)	$ (1.07)	$ (9.66)
Net income - basic (in dollars per share)						$ 0.04	$ (0.11)	$ (2.09)
Net income - diluted (in dollars per share)						$ 0.03	$ (0.11)	$ (2.09)