8. Stock-Based Compensation

2021 Equity Incentive Plan and 2021 Employee Stock Purchase Plan

In January 2021, the Company’s board of directors adopted the 2021 Equity Incentive Plan (the “2021 Plan”) and the Company’s stockholders approved the 2021 Plan. The 2021 Plan authorized issuance of up to 403,750 shares of common stock and it became effective upon the execution of the underwriting agreement for the Company’s IPO. In addition, the number of shares of common stock reserved for issuance under the 2021 Plan automatically increases on the first day of January of each calendar year that commences after the 2021 Plan became effective and continuing through and including January 1, 2031, in an amount equal to 5% of the total number of shares of the Company’s common stock outstanding on December 31, or a lesser number of shares determined by the Company's board of directors or compensation committee. As a result, common stock reserved for issuance under the 2021 Plan was increased by 96,028 shares on January 1, 2026.

In addition, in January 2021, the Company’s board of directors and stockholders adopted the 2021 Employee Stock Purchase Plan (the “ESPP”). The ESPP authorized issuance of up to 21,000 shares of common stock and it became effective

upon the execution of the underwriting agreement for the Company’s IPO. The ESPP permits participants to purchase common stock through payroll deductions of up to 15% of their eligible compensation. Employees purchase shares of common stock at a price per share equal to 85% of the lower of the fair market value at the start or end of six-month purchase periods within the two-year offering period. In addition, the number of shares of common stock reserved for issuance under the ESPP automatically increases on January 1 of each calendar year that commences after the ESPP became effective and continuing through and including January 1, 2031, by the lesser of (1) 1% of the total number of shares of the Company's common stock outstanding on December 31 of the preceding calendar year, (2) 42,000 shares, and (3) a number of shares determined by the Company's board of directors. As a result, common stock reserved for issuance under the 2021 ESPP was increased by 19,205 shares on January 1, 2026. During the six months ended June 30, 2026 and 2025, there were 4,778 and 2,498 shares issued under the ESPP, respectively.

Stock-Based Compensation Expense