Krystal Biotech, Inc.

Insider Trading Arrangements

On November 6, 2025, Kathryn Romano, our Chief Accounting Officer, adopted a Rule 10b5-1 trading arrangement that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act for the sale of up to 20,000 shares of the Company’s common stock and a gift of up to 750 shares of the Company’s common stock. The Rule 10b5-1 trading arrangement will continue until August 31, 2026, subject to early termination in accordance with the terms of the Rule 10b5-1 trading arrangement, including upon completion of the sale of all of the shares of the Company’s common stock subject to the Rule 10b5-1 trading arrangement.

On November 25, 2025, Daniel Janney, a member of the Company’s Board of Directors, adopted a Rule 10b5-1 trading arrangement that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act for the sale of up to 90,000 shares of the Company’s common stock, a portion of which will be issued upon exercise of stock options that if not exercised will expire in 2026. The Rule 10b5-1 trading arrangement will continue until November 5, 2026, subject to early termination in accordance with the terms of the Rule 10b5-1 trading arrangement, including upon completion of the sale of all of the shares of the Company’s common stock subject to the Rule 10b5-1 trading arrangement.

During the three months ended December 31, 2025, other than as disclosed above, none of our directors or officers (as that term is defined by the SEC in Rule 16a-1(f) under the Exchange Act) adopted or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement.