ACV Auctions Inc.

Our Section 16 officers (as defined in Rule 16a-1 under the Exchange Act) may from time to time enter into plans for the purchase or sale of ACV stock that are intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act.

During the quarter ended September 30, 2025, the following Section 16 officers adopted, modified, or terminated “Rule 10b5-1 trading arrangements” (as defined in Item 408 under Regulation S-K of the Exchange Act):

•On September 15, 2025, George Chamoun, ACV's Chief Executive Officer, terminated a trading plan. The Plan was originally entered into on June 13, 2025 and contemplated the sale of up to 600,000 shares between September 16, 2025 and March 13, 2026, excluding specified "No Sale" periods. Prior to its termination, the Plan was scheduled to terminate on March 13, 2026. No shares were sold under the Plan prior to termination.

•On September 15, 2025, George Chamoun, ACV's Chief Executive Officer, adopted a stock purchase plan. Mr. Chamoun's purchase plan provides for the purchase of up to $625,000 worth of shares. The first purchase will not occur until December 15, 2025 at the earliest. Mr. Chamoun's purchase plan is scheduled to terminate on June 15, 2026.

The Rule 10b5-1 trading arrangements described above were terminated, adopted, and pre-cleared in accordance with ACV’s Insider Trading Policy and actual sale transactions made pursuant to such trading arrangements will be disclosed publicly in future Section 16 filings with the SEC. Other than disclosed above, no other officer adopted, modified orterminated a Rule 10b5-1 trading arrangement or “non-Rule 10b5-1 trading arrangement” (as defined in Item 408 of Regulation S-K) during the three months ended June 30, 2025.