Korro Bio, Inc.

Trading Plans

During the three months ended December 31, 2024, the following officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted contracts, instructions or written plans for the purchase or sale of our securities that were intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act (each, a “Rule 10b5-1 plan”): On November 22, 2024, Vineet Agarwal, our Chief Financial Officer, adopted a Rule 10b5-1 plan providing for the potential sale of up to 10,085 shares of our common stock issuable upon the exercise of stock options; this plan is scheduled to expire on March 24, 2026. On November 22, 2024, Oliver Dolan, our SVP of Finance and Interim Principal Accounting Officer, adopted a Rule 10b5-1 plan providing for thepotential sale of up to 7,187 shares of our common stock issuable upon the exercise of stock options; this plan is scheduled to expire on December 31, 2025. During the three months ended December 31, 2024, none of our other officers or directors informed us that they adopted, modified orterminated a Rule 10b5-1 plan or a trading plan not intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act.