Waystar Holding Corp.

On August 24, 2025, Eric Lee (Ric) Sinclair III, our Chief Business Officer, adopted a trading plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. Mr. Sinclair’s plan provides for (i) the exercise of up to 90,750 vested stock options and the associated sale of up 90,750 shares of the Company’s common stock; (ii) the exercise of vested stock options and the associated sale shares of the Company’s common stock with the actual number of such options and associated shares to be determined based on unsold shares from Mr. Sinclair's previously adopted trading plan dated February 19, 2025; and (iii) the exercise of options subject to performance-based vesting conditions and the associated sale of shares of the Company’s common stock, with the actual number of such options and associated shares to be determined based on the level of achievement of the performance criteria associated with the award. Mr. Sinclair’s trading plan will expire December 31, 2026, or upon the earlier sale of all the shares subject to the plan.

On September 9, 2025, Craig Bridge, our Chief Transformation Officer, adopted a trading plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. Mr. Bridge’s plan provides for (i) the exercise of up to 112,485 vested stock options and the associated sale of up 112,485 shares of the Company’s common stock; (ii) the exercise of vested stock options and the associated sale shares of the Company’s common stock with the actual number of such options and associated shares to be determined based on unsold shares from Mr. Bridge's previously adopted trading plan dated November 27, 2024; and (iii) the exercise of options subject to performance-based vesting conditions and the associated sale of shares of the Company’s common stock, with the actual number of such options and associated shares to be determined based on the level of achievement of the performance criteria associated with the award. . Mr. Bridge’s trading plan will expire December 31, 2026, or upon the earlier sale of all the shares subject to the plan.

On September 11, 2025, Melissa Miller, our Chief Marketing Officer, adopted a trading plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. Ms. Miller’s plan provides for (i) the exercise of up to 101,470 vested stock options and the associated sale of up 101,470 shares of the Company’s common stock; and (ii) the exercise of options subject to performance-based vesting conditions and the associated sale of shares of the Company’s common stock, with the actual number of such options and associated shares to be determined based on the level of achievement of the performance criteria associated with the award. Ms. Miller’s trading plan will expire December 31, 2026, or upon the earlier sale of all the shares subject to the plan.

On September 11, 2025, Steven Oreskovich, our Chief Financial Officer, adopted a trading plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. Mr. Oreskovich’s plan provides for (i) the exercise of up to 519,277 vested stock options and the associated sale of up 519,277 shares of the Company’s common stock; and (ii) the exercise of options subject to performance-based vesting conditions and the associated sale of shares of the Company’s common stock, with the actual number of such options and associated shares to be determined based on the level of achievement of the performance criteria associated with the award. Mr. Oreskovich’s trading plan will expire December 31, 2026, or upon the earlier sale of all the shares subject to the plan.

On September 11, 2025, Christopher Schremser, our Chief Technology Officer, adopted a trading plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. Mr. Schremser’s plan provides for (i) the exercise of up to 454,682 vested stock options and the associated sale of up 454,682 shares of the Company’s common stock; and (ii) the exercise of options subject to performance-based vesting conditions and the associated sale of shares of the Company’s common stock, with the actual number of such options and associated shares to be determined based on the level of achievement of the performance criteria associated with the award. Mr. Schremser's trading plan will expire December 31, 2026, or upon the earlier sale of all the shares subject to the plan.

During the nine months ended September 30, 2025, none of the Company’s other directors or officers adopted, modified, orterminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement” as each term is defined in Item 408 of Regulation S-K.