X0609 4 2026-09-01 0 0001990354 Waystar Holding Corp. WAY 0001998256 Hawkins Matthew J. false 1550 DIGITAL DRIVE, #300 LEHI UT 84043 1 1 0 0 Chief Executive Officer 1 Common Stock 2026-09-01 4 F 0 30287 25.73 D 1804794 D Common Stock 2026-09-02 4 M 0 82500 4.14 A 1887294 D Common Stock 2026-09-02 4 S 0 82500 25.9707 D 1804794 D Stock Options (right to buy) 4.14 2026-09-02 4 M 0 82500 0 D 2027-11-01 Common Stock 82500 1510098 D Stock Options (right to buy) 4.14 2027-11-01 Common Stock 1592598 1510098 D Stock Options (right to buy) 4.14 2027-11-01 Common Stock 66374 66374 I By 2024 grantor retained annuity trust Stock Options (right to buy) 4.14 2027-11-01 Common Stock 46208 46208 I By 2025 grantor retained annuity trust The transaction represents shares of common stock withheld to pay taxes upon vesting of restricted stock units (RSUs) granted to the Reporting Person on April 1, 2025. The number of shares withheld was determined based on the actual sale price of shares sold on September 1, 2026 pursuant to a "sell-to-cover" transaction. The vesting schedule for this RSU grant, as originally reported on the Reporting Person's prior Form 4, was modified by the Talent & Compensation Committee. The original vesting schedule provided for 40% vesting on the third anniversary of the Vesting Commencement Date and 60% vesting on the fourth anniversary of the Vesting Commencement Date. The modified vesting schedule provides for 25% vesting on September 1, 2026, and 25% vesting on each of the second, third, and fourth anniversaries of the Vesting Commencement Date. Includes unvested RSUs. These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on March 13, 2026 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). The price reported in Column 4 is a weighted average price. These shares of common stock, par value $0.01 per share ("Common Stock") of Waystar Holding Corp. (the "Issuer") were sold in multiple transactions ranging from $25.51 to $26.51, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock sold at each separate price in the range set forth in this footnote. These options are currently vested. Reflects annuity payments resulting in a change in the form of beneficial ownership (direct and trust holdings) without a change in pecuniary interest, exempt under Rule 16a-13. /s/ Gregory R. Packer, as Attorney-in-Fact 2026-09-03