Company: CSTL
Filing Date: 2025-08-04
Form Type: 10-Q
Source: 0001447362-25-000097
Chunk: 28

Company: CASTLE BIOSCIENCES INC
Filing Date: 2025-08-04
Form: 10-Q
Item: Item 1
Chunk 28
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.48 Balance as of June 30, 20254,024,320$22.75 (1)The aggregate number of shares withheld upon vesting for employee tax obligations was 142,637 for the six months ended June 30, 2025.

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Table of ContentsCASTLE BIOSCIENCES, INC.NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (Continued)(UNAUDITED)

Performance-Based Restricted Stock UnitsThe following table summarizes our PSU activity for the six months ended June 30, 2025:Performance-Based Restricted Stock Units OutstandingWeighted-Average Grant Date Fair ValueBalance as of December 31, 2024275,528 $21.94 Granted172,631 $22.23 Vested— $— Forfeited/Cancelled— $— Balance as of June 30, 2025448,159$22.05 Employee Stock Purchase PlanThe ESPP provides for certain automatic increases in the number of shares of common stock reserved for issuance, which resulted in an additional 284,831 shares becoming available under the ESPP effective January 1, 2025. During the six months ended June 30, 2025, we issued 103,441 shares of common stock pursuant to scheduled purchases under the ESPP. As of June 30, 2025, 1,228,070 shares remained available for issuance under the ESPP.Determining Fair Value - Summary of AssumptionsWe use the Black-Scholes valuation model to estimate the fair value of the purchase rights issued under the ESPP at the date of grant, start of the offering or other relevant measurement date. The following table sets forth assumptions used under the ESPP: Six Months EndedJune 30,20252024Average expected term (years)1.21.3Expected stock price volatility 56.55% - 85.21%72.04% - 130.95%Risk-free interest rate 3.88% - 4.22%4.43% - 5.33%Dividend yield—%—%Fair ValueThere were no stock options granted for the six months ended June 30, 2025 and 2024. For the six months ended June 30, 2025 and 2024, the weighted-average grant date fair value of the purchase rights granted under the ESPP was $9.43 and $11.17 per share,