Stock-based Compensation Expense

6 Months Ended

Jun. 30, 2026

Stock-based Compensation Expense [Abstract]

9. Stock-based Compensation Expense

The following table summarizes stock-based compensation expense for the three and six months ended June 30, 2026 and 2025 (in thousands):


	Three Months Ended				Six Months Ended
	June 30,				June 30,
		2026		2025		2026		2025
Cost of sales	$	176	$	610	$	323	$	710
Research, development and patent expense		25,098		19,542		49,804		39,840
Selling, general and administrative expense		20,321		9,538		38,743		18,858
Stock-based compensation expense, net of amounts capitalized		45,595		29,690		88,870		59,408
Capitalized stock-based compensation expense		-		509		18		1,000
Total stock-based compensation expense	$	45,595	$	30,199	$	88,888	$	60,408

As of June 30, 2026, total unrecognized estimated stock-based compensation expense related to non-vested stock options, RSUs and PRSUs was $58.4 million, $166.6 million and $23.9 million, respectively. Our actual expenses will likely differ from these estimates because we will adjust our unrecognized stock-based compensation expense for future forfeitures, including any PRSUs that do not vest. We expect to recognize the cost of stock-based compensation expense related to our non-vested stock options, RSUs and PRSUs over a weighted average amortization period of 1.3 years, 1.6 years and 1.6 years, respectively.

Stock Options:

The weighted-average grant date fair value of stock options granted to employees for the six months ended June 30, 2026 and 2025 was $38.07 and $16.51 per share, respectively.

In the second quarter of 2026, two new members were appointed to the Board of Directors following the retirement of two Board members. In June 2026, we issued stock options to the two new Board members. The weighted-average grant date fair value of stock options granted to non-employee members of the Board of Directors for the six months ended June 30, 2026 was $39.04 per share. There were no stock options granted to non-employee members of the Board of Directors for the six months ended June 30, 2025 because no new members were appointed during the period.

RSUs:

The weighted-average grant date fair value of RSUs granted to employees for the six months ended June 30, 2026 and 2025 was $77.19 and $32.97 per share, respectively.

PRSUs:

Under the terms of the PRSUs we granted in 2026 and 2025, the PRSUs may vest at the end of the three-year performance period based on our relative total shareholder return, or TSR, as compared to a peer group of companies and as measured at the end of the performance period. Under the terms of the grants, no number of PRSUs is guaranteed to vest and the actual number of PRSUs that will vest at the end of each performance period may be anywhere from zero to 200 percent of the target number depending on our relative TSR.

The weighted-average grant date fair value of PRSUs we granted to our executive officers for the six months ended June 30, 2026 and 2025 was $115.05 and $48.81 per share, respectively.

Black-Scholes Assumptions:

For the six months ended June 30, 2026 and 2025, we used the following weighted-average assumptions in our Black-Scholes calculations:

Employee Stock Options:


	Six Months Ended
	June 30,
		2026		2025
Risk-free interest rate		3.9	%	4.5	%
Dividend yield		0.0	%	0.0	%
Volatility		43.1	%	42.0	%
Expected life		6.3 years		6.3 years

Board of Directors Stock Options:

	Six Months Ended
	June 30,
	2026
Risk-free interest rate	4.4	%
Dividend yield	0.0	%
Volatility	42.4	%
Expected life	7.3 years

ESPP:


	Six Months Ended
	June 30,
		2026		2025
Risk-free interest rate		3.6	%	4.3	%
Dividend yield		0.0	%	0.0	%
Volatility		51.7	%	41.3	%
Expected life		6 months		6 months