X0508 4 2026-01-20 0 0001990354 Waystar Holding Corp. WAY 0001998250 Sinclair III Eric L. (Ric) 1550 DIGITAL DRIVE, #300 LEHI UT 84043 0 1 0 0 Chief Business Officer 1 Common Stock 2026-01-20 4 M 0 7562 18.19 A 482388 D Common Stock 2026-01-20 4 M 0 32663 4.14 A 515051 D Common Stock 2026-01-20 4 S 0 40225 30.0827 D 474826 D Stock Options (right to buy) 18.19 2026-01-20 4 M 0 7562 0 D 2030-08-09 Common Stock 7562 173938 D Stock Options (right to buy) 4.14 2026-01-20 4 M 0 32663 0 D 2027-11-01 Common Stock 32663 6141 D Includes unvested RSUs. These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on August 24, 2025 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 $30.00 to $30.23, 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. Options granted on August 9, 2020 of which 50% of the option vests in five substantially equal annual installments commencing on August 9, 2021 and the remaining 50% of the option vests upon achievement of certain specified performance-based vesting criteria. These options are currently vested. /s/ Gregory R. Packer, as Attorney-in-Fact 2026-01-22