STOCK-BASED COMPENSATION
Stock-Based Compensation Expense
Stock-based compensation expense was recognized in the accompanying Statements of Operations and Comprehensive Loss as follows:
 Year Ended December 31,
 202520242023
Cost of sales$697 $603 $190 
Research and development10,035 6,804 5,833 
Selling, general and administrative30,988 20,411 13,807 
Total stock-based compensation$41,720 $27,818 $19,830 
Stock-based compensation expense was recognized by equity type as follows:
 Year Ended December 31,
 202520242023
Stock options$13,816 $15,182 $13,032 
Restricted stock units17,676 11,800 6,508 
Performance stock units9,232 — — 
Employee stock purchase plan996 836 290 
Total stock-based compensation$41,720 $27,818 $19,830 
As of December 31, 2025, total unrecognized stock-based compensation expense and average remaining vesting period by equity type is as follows:
Unrecognized Compensation Expense ($)Average Remaining Vesting Period (Years)
Stock options27,002 2.26
Restricted stock units43,214 2.69
Performance stock units23,218 2.00
The fair value of granted stock options was estimated as of the date of grant using the Black-Scholes option-pricing model, based on the following inputs:
 Year Ended December 31,
202520242023
Exercise price
$39.99 to $79.44
$20.16 to $50.40
$12.48 to $18.78
Risk-free interest rate
3.78% to 4.53%
3.57% to 4.65%
3.38% to 4.83%
Expected volatility
65.8% to 68.6%
69.3% to 71.6%
69.7% to 73.3%
Weighted-average grant-date fair value per stock option$45.78 $35.60 $15.49 
Stock Option Activity
Stock option activity during the year was as follows:
Number of
Shares
Weighted-Average
Exercise
Price/Share ($)
Weighted-Average
Remaining
Contractual
Term (Years)
Aggregate
Intrinsic
Value ($)(1)
Outstanding - December 31, 20245,007,908 19.29 6.91180,669 
Granted583,236 45.78 
Exercised(307,192)20.64 
Forfeited(52,827)24.66 
Outstanding - December 31, 20255,231,125 22.11 6.26312,647 
Vested - December 31, 20253,868,858 17.76 5.52248,052 
Unvested - December 31, 20251,362,267 34.46 8.3564,594 
(1) The aggregate intrinsic value is calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock as of December 31, 2025.
The total grant-date fair value of options that vested during the years ended December 31, 2025, 2024, and 2023, was $14.2 million, $13.5 million, and $13.4 million, respectively. The total intrinsic value of options exercised during the years ended December 31, 2025, 2024, and 2023 was $10.1 million, $7.0 million, and $1.6 million, respectively.
Restricted Stock Unit Activity
Restricted stock unit activity during the year was as follows:
Number of
Shares
Weighted-Average Grant Date
 Fair Value ($)
Outstanding - December 31, 20241,915,281 24.41 
Granted568,636 46.51 
Vested(598,256)23.62 
Forfeited(129,332)24.47 
Outstanding - December 31, 20251,756,329 31.83 
The total grant-date fair value of restricted stock units that vested during the years ended December 31, 2025, 2024, and 2023, was $14.1 million, $7.3 million, and $3.7 million, respectively.
Performance Stock Unit Activity
During the year ended December 31, 2025, the Company granted certain employees performance stock units. During the third quarter of 2025, the Company began recognizing stock-based compensation expense related to a performance condition that was determined to be probable of achievement.
Performance stock unit activity during the year was as follows:
Number of
Shares
Weighted-Average Grant Date
 Fair Value ($)
Outstanding - December 31, 2024— — 
Granted724,793 44.77 
Outstanding - December 31, 2025724,793 44.77 

About Stock Compensation Disclosures

Stock-based compensation disclosures detail the equity awards granted to employees and executives — including stock options, restricted stock units (RSUs), and performance shares — along with the valuation methods and assumptions used to expense them. This section reveals the true cost of talent retention and the alignment between management incentives and shareholder interests.

Key signals: total unrecognized compensation expense and its expected recognition period signal future earnings headwinds from already-granted awards. For stock options, examine Black-Scholes assumptions — expected volatility, risk-free rate, and expected term — as understating any of these reduces reported compensation expense. Compare stock compensation expense as a percentage of revenue against peers to assess dilution cost. Watch vesting schedules for acceleration clauses tied to change-of-control events. Performance-based awards with undemanding targets may indicate weak governance. Add back stock compensation to operating cash flow to calculate a more conservative free cash flow figure.