X0508 4 2026-02-27 0 0001711279 Krystal Biotech, Inc. KRYS 0001198325 JANNEY DANIEL C/O KRYSTAL BIOTECH, INC. 2100 WHARTON STREET, SUITE 701 PITTSBURGH PA 15203 1 0 0 0 1 Common Stock 2026-02-27 4 S 0 9430 275.4487 D 75666 I Directly beneficially owned by Alta Bioequities, L.P. Common Stock 2026-02-27 4 S 0 2373 276.1665 D 73293 I Directly beneficially owned by Alta Bioequities, L.P. The sale of common stock reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person. The Rule 10b5-1 trading plan was entered into on November 25, 2025, and will terminate on November 5, 2026, subject to early termination in accordance with the terms of the Rule 10b5-1 trading plan, including upon completion of the sale of all of the shares of the Company's common stock subject to the Rule 10b5-1 trading plan. The transaction was executed in multiple trades ranging from $275 to $275.986. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price within the range set forth herein. Alta Bioequities Management, LLC is the general partner of Alta Bioequities, L.P. and may be deemed to have sole voting and investment power over the shares beneficially owned by Alta Bioequities, L.P. The Reporting Person is the Managing Director of Alta Bioequities Management, LLC. The Reporting Person disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein. The transaction was executed in multiple trades ranging from $276 to $276.4924. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price within the range set forth herein. /s/ Krish Krishnan, as attorney-in-fact for Daniel Janney 2026-03-03