Accelerant Holdings

Rule 10b5-1 Trading Arrangements

During the three months ended March 31, 2026, none of the Company’s directors or officers adopted, modified orterminated any “Rule 10b5-1 trading arrangement” or any “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408 of Regulation S-K, except as follows:

•On March 24, 2026, Jeff Radke, Chief Executive Officer, entered into a Rule 10b5-1 trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c), with a term scheduled to end on June 21, 2027, relating to the sale of the lesser of (1)4,160,000 Class A common shares, or (2) a number of Class A common shares of the Company sufficient to generate $45.0 million in gross proceeds, exclusive of commissions. Assuming such shares are sold at an average price of $13.36 (the closing price on May 11, 2026), sales under the trading arrangement would represent approximately 11.8% of the shares beneficially owned by Mr. Radke as of the date of this Quarterly Report and the maximum number of shares that can be sold under the plan will not exceed 14.6% of such ownership.

•On February 18, 2026, Frank O'Neill, Chief Underwriting Officer, terminated a Rule 10b5-1 Trading Plan intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act that he had previously entered into on December 8, 2025. On March 23, 2026, Mr. O'Neill entered into a Rule 10b5-1 trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c), with a term scheduled to end on September 24, 2026, relating to the sale of the lesser of (1)1,600,730 Class A common shares, or (2) a number of Class A common shares of the Company sufficient to generate $12.33 million in gross proceeds, exclusive of commissions. Assuming such shares are sold at an average price of $13.36 (the closing price on May 11, 2026), sales under the trading arrangement would represent approximately 12.8% of the shares beneficially owned by Mr. O’Neill as of the date of this Quarterly Report and the maximum number of shares that can be sold under the plan will not exceed 22.1% of such ownership.

•On March 23, 2026, Christopher Lee-Smith, Head of Distribution, entered into a Rule 10b5-1 trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c), with a term scheduled to end on April 1, 2027, relating to the sale of up to 1,767,000 Class A common shares of the Company, which represents approximately 10% of the shares beneficially owned by Mr. Lee-Smith’s as of the date of this Quarterly Report.

The Company encourages the use of Rule 10b5‑1 plans to facilitate long‑term financial, tax and liquidity planning by executives.