ALUMIS INC.

Trading Arrangements

During the fourth quarter of 2025, neither the Company nor any of its director or officers adopted orterminated any 10b5-1 trading plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c ) or any other non-Rule 10b5-1 trading arrangement.

“At the Market” Equity Offering Program

On March 18, 2026, we entered into the Sales Agreement with Cantor as sales agent, pursuant to which we may offer and sell, from time to time through Cantor, at our option, shares of our common stock having an aggregate offering price of up to $300.0 million.

The sales of the ATM Shares will be made by any method permitted that is deemed to be an “at-the-market” equity offering as defined in Rule 415(a)(4) promulgated under the Securities Act, including sales made directly on or through the Nasdaq Global Select Market. We agreed to pay Cantor a commission of up to 3.0% of the aggregate gross proceeds from any ATM Shares sold by Cantor.

The foregoing description of the Sales Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Sales Agreement, a copy of which is filed as Exhibit 10.24 to this Annual Report on Form 10-K.

The foregoing disclosure shall not constitute an offer to sell or the solicitation of an offer to buy the securities discussed herein, nor shall there be any offer, solicitation, or sale of the securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.