The Company has maintained a stock incentive plan for the issuance of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock, other stock awards and performance cash awards, to employees, non-employee directors, and consultants. The Company also has an employee stock purchase plan (ESPP) for its employees.

The fair value of stock options granted to employees was estimated on the date of grant using the Black-Scholes option-pricing model with the following assumptions:


	Three Months Ended March 31,
	2026	2025
Expected term of options (in years)	6.1	6.1
Expected stock price volatility	93.3%	89.5% - 89.9%
Risk-free interest rate	3.8%-3.9%	4.1% - 4.5%
Expected dividend yield	—	—

Expected Term — The expected term represents the period that the stock options granted are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term) as the Company has limited historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants.

Expected Volatility — Prior to 2026, the expected volatility was determined by using a blended approach of the Company and its industry peers’ historical volatilities. Starting from 2026, the expected volatility is determined by using historical volatilities based on the Company’s stock prices over a look-back period corresponding to the expected term.

Risk-Free Interest Rate — The Company determines the risk-free interest rate over the expected term of the stock options based on the constant maturity rate of U.S. Treasury securities with similar maturities as of the date of the grant.

Expected Dividend Rate — The expected dividend is zero as the Company has not paid nor does it anticipate paying any dividends in the foreseeable future.

Stock-based compensation is recognized on a straight-line basis over the requisite service period, which is generally the vesting period. The following table sets forth the total stock-based compensation expense for all awards granted to employees and non-employees and the ESPP in the unaudited condensed consolidated statements of operations (in thousands):


	Three Months Ended March 31,
	2026		2025
Research and development	$	6,022	$	7,005
Selling, general and administrative	6,065		7,054
Total stock-based compensation	$	12,087	$	14,059