XML 56 R39.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Stock-based Compensation (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2024
Share-Based Payment Arrangement [Abstract] |
Schedule of Stock-based Compensation Expense | Stock-based compensation expense is included in the consolidated statements of operations as follows (in thousands):
| Year Ended December 31,
| 2024 |  | 2023 |  | 2022
Costs of product revenue | $ | 429 |  |  | $ | 354 |  |  | $ | 452 |
Research and development | 2,928 |  |  | 2,631 |  |  | 3,907 |
Selling, general and administrative | 9,730 |  |  | 6,986 |  |  | 10,172 |
Total | $ | 13,087 |  |  | $ | 9,971 |  |  | $ | 14,531 |
The following table presents total stock-based compensation expense by security type included in the consolidated statements of operations (in thousands):
| Year Ended December 31,
| 2024 |  | 2023 |  | 2022
Stock options | $ | 6,423 |  |  | $ | 3,962 |  |  | $ | 4,167 |
RSUs and RSAs | 4,717 |  |  | 4,447 |  | 4,807
PSUs | 247 |  |  | 1,649 |  |  | 3,268 |
PBOs | 1,357 |  |  | $ | (112) |  |  | 2,289
ESPP | 343 |  |  | 25 |  |  | — |
Total | $ | 13,087 |  |  | $ | 9,971 |  |  | $ | 14,531 |
Schedule of Assumptions Used to Estimate the Fair Value of Option Grants | The following summarizes the weighted-average assumptions used to estimate the fair value of employee stock options granted:
| Year Ended December 31,
| 2024 |  | 2023 |  | 2022
Expected life (years) | 5.9 |  | 5.8 |  | 5.7
Volatility | 73.3 | % |  | 66.2 | % |  | 62.1 | %
Risk-free interest rate | 3.9 | % |  | 4.0 | % |  | 3.1 | %
Expected dividend yield | 0.0 | % |  | 0.0 | % |  | 0.0 | %
The following summarizes the weighted-average assumptions used to estimate the fair value of 20,000 and 50,000 shares of stock options granted to non-employees for services valued at $44 thousand and $0.1 million during the years ended December 31, 2024 and 2023, respectively:
| Year Ended December 31,
| 2024 |  | 2023
Expected life (years) | 5.8 |  | 5.8
Volatility | 74.7 | % |  | 70.1 | %
Risk-free interest rate | 4.4 | % |  | 4.7 | %
Expected dividend yield | 0.0 | % |  | 0.0 | %
The following summarize the weighted-average assumptions used to estimate the fair value of PBOs granted:
| Year Ended December 31,
| 2022
Expected life (years) | 5.6
Volatility | 54.9 | %
Risk-free interest rate | 1.8 | %
Expected dividend yield | 0.0 | %
Schedule of Share-based Compensation, Stock Options, Activity | The following tables summarize s stock option activities:
| Number of Shares |  | Weighted Average Exercise Price Per Share
| (In Thousands) |  |
Outstanding at December 31, 2021 | 2,935 |  |  | $ | 8.90 |
Granted | 2,000 |  |  | $ | 8.90 |
Exercised | (410) |  |  | $ | 2.33 |
Forfeited/Expired | (275) |  |  | $ | 19.01 |
Outstanding at December 31, 2022 | 4,250 |  |  | $ | 8.88 |
Granted | 2,046 |  |  | $ | 5.23 |
Exercised | (283) |  |  | $ | 1.97 |
Forfeited/Expired | (839) |  |  | $ | 12.08 |
Outstanding at December 31, 2023 | 5,174 |  |  | $ | 7.31 |
Granted | 4,837 |  |  | $ | 3.08 |
Exercised | (399) |  |  | $ | 3.24 |
Forfeited/Expired | (484) |  |  | $ | 8.75 |
Outstanding at December 31, 2024 | 9,128 |  |  | $ | 5.17 |
| Number of Shares |  | Weighted Average Exercise Price Per Share |  | Weighted Average Remaining Contractual Term |  | Aggregate Intrinsic Value
| (In Thousands) |  |  |  | (In Years) |  | (In Thousands)
Outstanding at December 31, 2024 | 9,128 |  |  | $ | 5.17 |  |  | 6.3 |  | $ | 8,497 |
Exercisable at December 31, 2024 | 2,840 |  |  | $ | 8.05 |  |  | 4.5 |  | $ | 402 |
Vested and expected to vest at December 31, 2024 | 8,508 |  |  | $ | 5.27 |  |  | 6.2 |  | $ | 7,724 |
Schedule of Share-based Compensation, RSA Activity | The following table summarizes RSA activities:
| Number of Shares |  | Weighted Average Grant Date Fair Value Per Share
| (In Thousands) |  |
Non-vested balance at December 31, 2021 | 80 |  |  | $ | 17.53 |
Granted | 159 |  |  | $ | 7.53 |
Vested | (58) |  |  | $ | 18.42 |
Non-vested balance at December 31, 2022 | 181 |  |  | $ | 8.45 |
Granted | 277 |  |  | $ | 2.89 |
Vested | (133) |  |  | $ | 9.04 |
Non-vested balance at December 31, 2023 | 325 |  |  | $ | 3.48 |
Granted | 211 |  |  | $ | 3.32 |
Vested | (302) |  |  | $ | 3.31 |
Non-vested balance at December 31, 2024 | 234 |  |  | $ | 3.56 |
Schedule of Share-based Compensation, RSU Activity | The following table summarizes RSU activities:
| Number of Shares |  | Weighted Average Grant Date Fair Value Per Share
| (In Thousands) |  |
Non-vested balance at December 31, 2021 | 232 |  |  | $ | 21.83 |
Granted | 518 |  |  | $ | 17.46 |
Vested | (106) |  |  | $ | 21.21 |
Forfeited/Expired | (126) |  |  | $ | 19.55 |
Non-vested balance at December 31, 2022 | 518 |  |  | $ | 18.15 |
Granted | 1,049 |  |  | $ | 5.24 |
Vested | (204) |  |  | $ | 18.42 |
Forfeited/Expired | (343) |  |  | $ | 9.71 |
Non-vested balance at December 31, 2023 | 1,020 |  |  | $ | 7.66 |
Granted | 1,530 |  |  | $ | 3.08 |
Vested | (383) |  |  | $ | 8.96 |
Forfeited/Expired | (157) |  |  | $ | 4.66 |
Non-vested balance at December 31, 2024 | 2,010 |  |  | $ | 4.16 |
Schedule of Share-based Compensation, Performance Shares Award Outstanding Activity | The following table summarizes PSU activities:
| Number of Shares |  | Weighted Average Grant Date Fair Value Per Share
| (In Thousands) |  |
Non-vested balance at December 31, 2021 | 128 |  |  | $ | 21.24 |
Granted | 686 |  |  | $ | 9.55 |
Vested | (107) |  |  | $ | 20.52 |
Forfeited/Expired | (40) |  |  | $ | 19.93 |
Non-vested balance at December 31, 2022 | 667 |  |  | $ | 9.41 |
Vested | (315) |  |  | $ | 11.02 |
Forfeited/Expired | (75) |  |  | $ | 12.49 |
Other | 15 |  |  | $ | 25.05 |
Non-vested balance at December 31, 2023 | 292 |  |  | $ | 7.69 |
Vested | (248) |  |  | $ | 7.69 |
Forfeited/Expired | (44) |  |  | $ | 7.69 |
Non-vested balance at December 31, 2024 | — |  |  | $ | — |
The following tables summarizes PBOs activities:
| Number of Shares |  | Weighted Average Grant Date Fair Value Per Share
| (In Thousands) |  |
Outstanding at December 31, 2021 | 1,840 |  |  | $ | 4.11 |
Granted | 733 |  |  | $ | 9.89 |
Forfeited/Expired | (747) |  |  | $ | 8.29 |
Outstanding at December 31, 2022 | 1,826 |  |  | $ | 4.70 |
Forfeited/Expired | (178) |  |  | $ | 9.73 |
Outstanding at December 31, 2023 | 1,648 |  |  | $ | 5.64 |
Forfeited/Expired | (73) |  |  | $ | 10.23 |
Outstanding at December 31, 2024 | 1,575 |  |  | $ | 5.43 |
| Number of Shares |  | Weighted Average Exercise Price Per Share |  | Weighted Average Remaining Contractual Term |  | Aggregate Intrinsic Value
| (In Thousands) |  |  |  | (In Years) |  | (In Thousands)
Exercisable at December 31, 2024 | 1,575 |  |  | $ | 10.62 |  |  | 3.4 |  | $ | 114 |
Vested and expected to vest at December 31, 2024 | 1,575 |  |  | $ | 10.62 |  |  | 3.4 |  | $ | 114 |
Schedule of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions | The fair value of shares to be issued under the ESPP is computed using the Black-Scholes-Merton option pricing model at the commencement of the offering period. The following summarizes the weighted-average assumptions used to estimate the fair value of ESPP for the initial offering period:
| Year Ended December 31,
| 2024 |  | 2023
Expected life (years) | 1.2 |  | 0.4
Volatility | 89.4 | % |  | 89.6 | %
Risk-free interest rate | 4.6 | % |  | 5.3 | %
Expected dividend yield | 0.0 | % |  | 0.0 | %

X
- References No definition available. + Details
Name: | us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited during the year. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -SubTopic 10 -Topic 718 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (e) -SubTopic 10 -Topic 718 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of employee stock purchase plans, including, but not limited to: (a) expected term, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Subparagraph (f)(2) -Name Accounting Standards Codification -Paragraph 2 -Section 50 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanValuationAssumptionsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Subparagraph (f)(2) -Name Accounting Standards Codification -Paragraph 2 -Section 50 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Disclosure of the number and weighted-average grant date fair value for restricted stock and restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock and restricted stock units that were granted, vested, or forfeited during the year. + References No definition available. + Details
Name: | us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the number and weighted-average grant date fair value for outstanding performance shares. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Subparagraph (c) -Paragraph 2 -SubTopic 10 -Topic 718 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ShareBasedCompensationPerformanceSharesAwardOutstandingActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration