X0609 4 2026-09-04 0 0001711279 Krystal Biotech, Inc. KRYS 0001298711 Krishnan Suma false C/O KRYSTAL BIOTECH, INC. 2100 WHARTON STREET, SUITE 701 PITTSBURGH PA 15203 1 1 1 0 President, R&D 1 Common Stock 2026-09-04 4 S 0 520 354.54 D 1326625 D Common Stock 2026-09-04 4 S 0 2006 355.5719 D 1324619 D Common Stock 2026-09-04 4 S 0 3267 356.3679 D 1321352 D Common Stock 2026-09-04 4 S 0 3962 357.5742 D 1317390 D Common Stock 2026-09-04 4 S 0 3180 358.4203 D 1314210 D Common Stock 2026-09-04 4 S 0 3392 359.3862 D 1310818 D Common Stock 2026-09-04 4 S 0 2320 360.466 D 1308498 D Common Stock 2026-09-04 4 S 0 1242 361.61 D 1307256 D Common Stock 2026-09-04 4 S 0 1992 362.6527 D 1305264 D Common Stock 2026-09-04 4 S 0 565 363.3404 D 1304699 D Common Stock 2026-09-04 4 S 0 1329 364.4771 D 1303370 D Common Stock 2026-09-04 4 S 0 826 365.4139 D 1302544 D Common Stock 2026-09-04 4 S 0 399 366.556 D 1302145 D Common Stock 90000 I By Krishnan Spousal Trust Common Stock 51010 I By Suma Mani Krishnan Trust Common Stock 50000 I By Krishnan Family Trust The Reporting Person may be deemed to beneficially own shares of the Issuer's common stock directly owned by the Reporting Person's spouse, Krish S. Krishnan. Such shares and transactions by the Reporting Person's spouse are not included in this Form 4, as they are being reported separately on a Form 4 filed by her spouse. The Reporting Person disclaims beneficial ownership of such shares except to the extent of her pecuniary interest therein. The sales reported were pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 4, 2025. The Rule 10b5-1 trading plan has reached the maximum number of shares to be sold under such plan and has terminated. The transaction was executed in multiple trades ranging from $353.98 to $354.97. 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. The transaction was executed in multiple trades ranging from $354.98 to $355.97. 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. The transaction was executed in multiple trades ranging from $355.98 to $356.96. 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. The transaction was executed in multiple trades ranging from $356.99 to $357.97. 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. The transaction was executed in multiple trades ranging from $357.99 to $358.98. 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. The transaction was executed in multiple trades ranging from $358.99 to $359.98. 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. The transaction was executed in multiple trades ranging from $360.01 to $361.005. 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. The transaction was executed in multiple trades ranging from $361.02 to $362.00. 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. The transaction was executed in multiple trades ranging from $362.02 to $363.00. 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. The transaction was executed in multiple trades ranging from $363.05 to $364.01. 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. The transaction was executed in multiple trades ranging from $364.07 to $365.05. 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. The transaction was executed in multiple trades ranging from $365.07 to $366.03. 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. The transaction was executed in multiple trades ranging from $366.39 to $366.91. 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. Held by the Krishnan Spousal Trust, an irrevocable trust established by Mr. Krishnan for the benefit of Mrs. Krishnan who serves as a co-trustee and shares voting and investment power with a 3rd party co-trustee. Held by the Suma Mani Krishnan Trust dated July 7, 2026. The Reporting Person is the grantor and trustee of the trust, has the power to revoke the trust, and has voting and investment power with respect to the shares held by the trust. Held by the Krishnan Family Trust. The Reporting Person and her spouse are each joint beneficial owners of the trust with joint voting and investment control. /s/ Suma M. Krishnan 2026-09-04