Krystal Biotech, Inc.

Insider Trading Arrangements

On August 31, 2026, Kathryn Romano, our Executive Vice President & 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 11,527 shares of our common stock (including up to 10,927 shares to be acquired upon the exercise of vested stock options), the exercise of vested stock options for up to 1,573 shares of our common stock to be held by Ms. Romano, and a charitable gift of up to 1,163 shares of our common stock, in each case subject to certain conditions. The trading arrangement will terminate on December 31, 2027, subject to early termination in accordance with its terms, including upon the completion of all transactions contemplated by the trading arrangement.

On September 10, 2026, Laurent Goux, our Executive Vice President, Head of International, 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 3,045 shares of our common stock to be acquired upon the exercise of vested stock options, subject to certain conditions. The trading arrangement will terminate on September 10, 2027, subject to early termination in accordance with its terms, including upon the completion of the sale of all of the shares of our common stock subject to the trading arrangement.

During the three months ended September 30, 2026, other than as disclosed above, no director or officer (as that term is defined by the SEC in Rule 16a-1(f) under the Exchange Act)adopted orterminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408 of Regulation S-K.