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Stock Incentive Plans and Stock Based Compensation
 12 Months Ended
Dec. 31, 2025
Share-Based Payment Arrangement [Abstract]  
Stock Incentive Plans and Stock Based Compensation Stock Incentive Plans and Stock-Based Compensation
Equity Incentive Plans
On July 24, 2019, we adopted the 2019 Equity Incentive Plan (the “2019 Plan”). As of December 31, 2025, there were 1,279,290 shares remained available for grant under the 2019 Plan. The 2019 Plan provides for automatic annual increases to the number of shares authorized for issuance, equal to 5% of our common shares outstanding as of the immediately preceding year end, through January 1, 2029. Under this provision, effective January 1, 2026, an additional 1,484,315 shares became available under the 2019 Plan.
Prior to adopting the 2019 Plan, we had adopted the 2008 Stock Plan (the “2008 Plan”) on September 6, 2008 and the 2018 Stock Plan (the “2018 Plan”) on August 15, 2018. No additional shares have been issued from each respective plan following the chronological adoption of each succeeding plan.
Our stock incentive plans provide for the granting of awards to employees, directors and consultants. Available awards under our incentive plans include options to purchase common stock as well as RSU, PSUs and other equity-based awards providing recipients the right to receive common shares.
Inducement Plan
On December 22, 2022, our board of directors approved the 2022 Inducement Plan (the “Inducement Plan”). The Inducement Plan provides for the granting of awards as inducement material to the grantee’s entering into employment with us to the extent such grantee was not previously an employee of ours or is entering into employment following a bona fide period of non-employment with us. On August 5, 2025, our compensation committee amended the Inducement Plan to increase the number of shares issuable under the Inducement Plan by 700,000 shares. As of December 31, 2025, there were 718,454 shares available for grant under the amended Inducement Plan.
Options Granted Under our Plans
Our 2019 Plan and Inducement Plan provide for the granting of options in form of incentive stock options (“ISO”) and non-statutory stock options (“NSOs”). ISOs may only be granted to our employees and employee-directors. NSOs may be granted to our employees, employee-directors, nonemployee directors and consultants. Options may be granted for terms up to ten years from the date of grant, as determined by the board of directors; provided, however, that with respect to an ISO granted to a person who owns stock representing more than 10% of the voting power of all classes of stock of ours, the terms shall be for no more than five years from the date of grant. The exercise price of options granted must be no less than 100% of the fair market value of the shares on the date of grant, provided, however, that with respect to an ISO granted to an employee who at the time of grant of such options owns stock representing more than 10% of the voting power of all classes of stock of ours, the exercise price shall not be less than 110% of the fair market value of the shares on the date of grant. Options generally vest over four years (generally 25% after one year and monthly thereafter), subject to the option holder’s continued service with us. We issue new shares to satisfy option exercises.
Stock Options
The following table summarizes our stock option activity:
  Weighted-Average 
 Stock Options
Outstanding		Exercise
Price		Remaining
Contractual
Term (Years)		Aggregate
Intrinsic
Value
(in thousands)
Balance as of January 1, 20233,419,840 $35.11 
Granted170 $25.06 
Exercised(71,525)$3.77 
Forfeited/Cancelled(139,506)$44.87 
Balance as of December 31, 20233,208,979 $35.38 
Granted3,379 $71.22 
Exercised(135,875)$14.85 
Forfeited/Cancelled(86,720)$39.74 
Balance as of December 31, 20242,989,763 $36.23 
Granted— $— 
Exercised(108,458)$20.34 
Forfeited/Cancelled(96,873)$45.51 
Balance as of December 31, 20252,784,432 $36.53 4.6$24,372 
Exercisable as of December 31, 20252,779,739 $36.55 4.6$24,306 
Restricted Stock Units
RSUs represent the right to receive shares of our common stock at a specified future date, subject to vesting. Our RSUs generally vest annually from the grant date in four equal installments subject to the holder’s continued service with us. We issue new shares of common stock upon the vesting of RSUs.
The following table summarizes our RSU activity:
Restricted Stock Units OutstandingWeighted-Average Grant Date Fair Value
Balance as of January 1, 20233,477,922 $27.56 
Granted549,296 $17.92 
Vested(1)
(901,547)$28.85 
Forfeited/Cancelled(320,596)$25.62 
Balance as of December 31, 20232,805,075 $25.48 
Granted1,708,028 $22.37 
Vested(1)
(982,403)$27.68 
Forfeited/Cancelled(334,476)$21.79 
Balance as of December 31, 20243,196,224 $23.52 
Granted1,715,247 $22.65 
Vested(1)
(1,237,950)$25.38 
Forfeited/Cancelled(277,759)$23.38 
Balance as of December 31, 20253,395,762 $22.42 
(1)The aggregate number of shares withheld upon vesting for employee tax obligations was 366,776, 281,275 and 254,197 for the years ended December 31, 2025, 2024 and 2023, respectively.
Performance-Based Restricted Stock Units
PSUs represent the right to receive shares of our common stock contingent upon the achievement of certain financial performance measures. We issue new shares of common stock upon the vesting of PSUs.
On August 9, 2024 (the “Initial Vesting Date”), the board of directors certified that the revenue goal for the PSUs granted on December 23, 2022 (“2022 PSUs”) was achieved. Therefore, 50% of the 2022 PSUs were vested and we immediately recognized approximately $0.1 million of stock-based compensation related to this performance metric. The remaining 50% of the 2022 PSUs were subject to time-based vesting and vested in full on August 9, 2025.
The following table summarizes our PSU activity:
Performance-Based Restricted Stock Units OutstandingWeighted-Average Grant Date Fair Value
Balance as of January 1, 2023196,033 $23.23 
Granted— $— 
Vested— $— 
Forfeited/Cancelled— $— 
Balance as of December 31, 2023196,033 $23.23 
Granted177,513 $21.23 
Vested(1)
(98,018)$23.23 
Forfeited/Cancelled— $— 
Balance as of December 31, 2024275,528 $21.94 
Granted172,631 $22.23 
Vested(1)
(98,015)$23.23 
Forfeited/Cancelled— $— 
Balance as of December 31, 2025350,144 $21.72 
(1)The aggregate number of shares withheld upon vesting for employee tax obligations was 35,426 and 30,046 for the years ended December 31, 2025 and 2024, respectively.
Employee Stock Purchase Plan
The ESPP became effective July 24, 2019. Offerings under the ESPP are generally 24 months in length with four six-month purchase periods unless terminated earlier, as described below. Eligible employees who enroll in an offering are able to purchase shares of our common stock at a discount through payroll deductions, subject to certain limitations. The purchase price of the shares of common stock is the lesser of (i) 85% of the fair market value of such shares on the offering date and (ii) 85% of the fair market value of such shares on the purchase date. A new offering begins approximately every six months. Offerings are concurrent, but in the event the fair market value of a share of common stock on the first day of any purchase period during an offering (the “New Offering”) is less than or equal to the fair market value of a share of common stock on the offering date for an ongoing offering (the “Ongoing Offering”), then the Ongoing Offering terminates immediately following the purchase of shares on the purchase date immediately preceding the New Offering and the participants in the terminated Ongoing Offering are automatically enrolled in the New Offering. In such case, we account for this event as a modification of the Ongoing Offering. Notwithstanding the above, our board of directors (or an authorized committee thereof) may modify the terms of or suspend any future offerings prior to their commencement.
As of December 31, 2025, 1,170,613 shares remained available for issuance under the ESPP. The ESPP provides for certain automatic increases in the number of shares of common stock reserved for issuance, which resulted in an additional 296,863 shares becoming available under the ESPP effective January 1, 2026. We issue new shares to satisfy the ESPP purchases.
Determining Fair Value - Summary of Assumptions
We use the closing price of our common stock on the date of grant to determine the fair value of RSUs and PSUs.
We use the Black-Scholes option-pricing model to estimate the fair value of stock options and purchase rights issued under the ESPP at the date of grant, start of the offering or other relevant measurement date. Set forth below is a description of the significant assumptions used:
•Expected term. The expected term is the period of time that granted options are expected to be outstanding. For stock options, we have set the expected term using the simplified method based on the weighted-average of both the period to vesting and the period to maturity for each option, as we have concluded that its stock option exercise history does not provide a reasonable basis upon which to estimate the expected term. For the ESPP, the expected term is the period of time from the offering date to the purchase date.
•Expected volatility. For our ESPP, we estimate expected volatility based on the historical volatility of our common stock. For stock options, we previously estimated expected volatility using the historical stock prices of a group of comparable companies, together with our own stock price on a relative basis, due to the limited period during which our common stock had been actively traded. Beginning in the third quarter of 2025, our common stock established a sufficient trading history and, therefore, we use solely the historical volatility of our own stock in determining expected volatility.
•Risk-free interest rate. We base the risk-free interest rate used in the Black-Scholes valuation model on the market yield in effect at the time of option grant and at the offering date for the ESPP, provided from the Federal Reserve Board’s Statistical Releases and historical publications from the Treasury constant maturities rates for the equivalent remaining terms.
•Dividend yield. We have not paid, and do not have plans to pay, cash dividends. Therefore, we use an expected dividend yield of zero in the Black-Scholes option valuation model.
The fair value of our common stock is also an assumption used to determine the fair value of stock options. The fair value of our common stock is the closing selling price per share of its common stock as reported on the Nasdaq Global Market on the date of grant or other relevant determination date.
We use the Black-Scholes option pricing model to estimate the fair value of each option grant on the date of grant or any other measurement date. The following table sets forth the assumptions used to determine the fair value of stock options:
 Years Ended December 31,
2025(1)
20242023
Average expected term (years)
N/A
5.0
5.0
Expected stock price volatility
N/A
80.20% - 80.20%
75.57% - 76.01%
Risk-free interest rate
N/A
4.39% - 4.39%
3.57% - 3.57%
Dividend yield
N/A
—%
—%
(1)For the year ended December 31, 2025, no stock options were granted.
The following table sets forth assumptions used to determine the fair value of the purchase rights issued under the ESPP:
 Years Ended December 31,
202520242023
Average expected term (years)
1.2
1.2
1.3
Expected stock price volatility
56.55% - 85.21%
59.85% - 105.39%
72.80% - 130.95%
Risk-free interest rate
3.52% - 4.22%
3.82% - 5.14%
4.74% - 5.33%
Dividend yield
—%
—%
—%
Fair Value and Intrinsic Value
For the year ended December 31, 2025, no stock options were granted. For the years ended December 31, 2024 and 2023 the weighted-average grant date fair value of stock options was $9.23 and $15.99 per option, respectively. For the years ended December 31, 2025, 2024 and 2023 the weighted-average grant date fair value of the purchase rights issued under the ESPP was $9.71, $12.66 and $11.43 per share, respectively.
The aggregate intrinsic value of stock options exercised during the years ended December 31, 2025, 2024 and 2023 was $1.2 million, $1.7 million and $1.3 million, respectively. The aggregate intrinsic value of shares issued under the ESPP was $0.9 million, $1.0 million and $0.5 million during the years ended December 31, 2025, 2024 and 2023, respectively.
The aggregate fair value of RSUs that vested during the years ended December 31, 2025, 2024 and 2023 was $36.1 million, $27.7 million and $18.1 million, respectively.
Stock-Based Compensation Expense
Stock-based compensation expense is included in the consolidated statements of operations as follows (in thousands):
 Years Ended December 31,
 202520242023
Cost of sales (exclusive of amortization of acquired intangible assets)$5,666 $5,529 $4,938 
Research and development7,555 9,598 10,119 
Selling, general and administrative32,672 35,193 36,162 
Total stock-based compensation expense$45,893 $50,320 $51,219 
Included in total stock-based compensation expense for the years ended December 31, 2025, 2024 and 2023 is $0.7 million, $0.7 million and $1.6 million, respectively, from the accelerated recognition of expense for modifications of awards falling in scope of the Retirement Policy.
No tax benefits related to stock-based compensation expense were recorded in the consolidated statements of operations during the years ended December 31, 2025, 2024 and 2023 due to the valuation allowance on net deferred tax assets.
As of December 31, 2025, the total unrecognized stock-based compensation cost related to outstanding awards was $64.7 million, which is expected to be recognized over a weighted-average period of 2.4 years. The total unrecognized compensation cost will be adjusted for forfeitures in future periods as they occur.