Frank Stokes - 03 Mar 2026 Form 4 Insider Report for CASTLE BIOSCIENCES INC (CSTL)

Role
Chief Financial Officer
Signature
/s/ Frank Stokes, Attorney-in-fact
Issuer symbol
CSTL
Transactions as of
03 Mar 2026
Net transactions value
-$192,073
Form type
4
Filing time
05 Mar 2026, 17:08:38 UTC
Previous filing
14 Jan 2026
Next filing
09 Mar 2026
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Stokes Frank Chief Financial Officer C/O CASTLE BIOSCIENCES, INC., 1500 W. PARKWOOD AVE SUITE 400, FRIENDSWOOD /s/ Frank Stokes, Attorney-in-fact 05 Mar 2025 0001782815

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction CSTL Common Stock Sale $144,796 -5,300 -8.9% $27.32 54,183 03 Mar 2026 Direct F1, F2, F3
transaction CSTL Common Stock Sale $47,277 -1,700 -3.1% $27.81 52,483 03 Mar 2026 Direct F1, F4
transaction CSTL Common Stock Tax liability -3,611 -6.9% $27.57* 48,872 03 Mar 2026 Direct F5
transaction CSTL Common Stock Options Exercise +24,146 +49% 73,018 04 Mar 2026 Direct F6
transaction CSTL Common Stock Tax liability -10,732 -15% $28.17* 62,286 04 Mar 2026 Direct
transaction CSTL Common Stock Options Exercise +3,800 +6.1% $3.38* 66,086 04 Mar 2026 Direct

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction CSTL Restricted Stock Units Award +48,367 $0.000000* 48,367 03 Mar 2026 Common Stock 48,367 Direct F6, F7
transaction CSTL Restricted Stock Units Options Exercise -12,186 -33% $0.000000* 24,372 04 Mar 2026 Common Stock 12,186 Direct F6, F8
transaction CSTL Restricted Stock Units Options Exercise -11,960 -25% $0.000000* 35,878 04 Mar 2026 Common Stock 11,960 Direct F6, F9
transaction CSTL Stock option (right to buy) Options Exercise -3,800 -20% $0.000000* 14,912 04 Mar 2026 Common Stock 3,800 $3.38 Direct F10
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

Transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Explanation of Responses:

Id Content
F1 The transaction on this Form 4 was made pursuant to a Rule 10b5-1 plan adopted by Frank Stokes on November 13, 2025.
F2 This transaction was executed in multiple trades at prices ranging from $26.70 to $27.67, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
F3 Includes 1,033 shares acquired on February 27, 2026, under the Issuer's employee stock purchase plan.
F4 This transaction was executed in multiple trades at prices ranging from $27.72 to $27.97, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
F5 Reflects the withholding of shares of the Issuer's common stock to satisfy tax withholding obligations in connection with the delivery of vested performance stock units reported on January 12, 2026.
F6 Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock.
F7 The RSU's vest in four equal annual installments beginning on March 03, 2027.
F8 On March 4, 2024, the Reporting Person was granted 48,744 RSUs which vest in four equal installments beginning on March 4, 2025.
F9 On March 4, 2025, the Reporting Person was granted 47,838 RSUs which vest in four equal installments beginning on March 4, 2026.
F10 The shares subject to the option are fully vested.