Pierre Abinakle, Managing Director, Head of Compliance

SCHEDULE 13G/A 0001104659-24-117985 0001283718 XXXXXXXX LIVE 3 Common Stock 09/30/2025 0001990354 Waystar Holding Corp. 946784105 1550 Digital Drive #300 Lehi UT 84043 Rule 13d-1(d) Canada Pension Plan Investment Board Z4 0.00 19025452.00 0.00 19025452.00 19025452.00 N 9.9 FI Item 11 is calculated based on a total of 191,316,583 shares of common stock of the issuer outstanding as of October 20, 2025, as disclosed in the issuer's Form 10-Q filed with the Securities and Exchange Commission on October 29, 2025. Shares reported on this Schedule 13G are held directly by CPP Investment Board Private Holdings (4) Inc., a wholly-owned subsidiary of Canada Pension Plan Investment Board. CPP Investment Board Private Holdings (4) Inc. Z4 0.00 19025452.00 0.00 19025452.00 19025452.00 N 9.9 CO Item 11 is calculated based on a total of 191,316,583 shares of common stock of the issuer outstanding as of October 20, 2025, as disclosed in the issuer's Form 10-Q filed with the Securities and Exchange Commission on October 29, 2025. Shares reported on this Schedule 13G are held directly by CPP Investment Board Private Holdings (4) Inc., a wholly-owned subsidiary of Canada Pension Plan Investment Board. Waystar Holding Corp. 1550 Digital Drive #300 Lehi, UT, 84043 Canada Pension Plan Investment Board CPP Investment Board Private Holdings (4) Inc. One Queen Street East, Suite 2500, Toronto, Ontario M5C 2W5 Canada Canada (Federal) Y See Item 9 on pages 2 and 3. See Item 11 on pages 2 and 3. See Item 5 on pages 2 and 3. See Item 6 on pages 2 and 3. See Item 7 on pages 2 and 3. See Item 8 on pages 2 and 3. Y Y Y Y Y Y 99.1 Power of Attorney of Canada Pension Plan Investment Board (incorporated by reference to Exhibit 99.1 of the Schedule 13G/A filed by the reporting persons in respect of the issuer on March 6, 2025). Canada Pension Plan Investment Board /s/ Pierre Abinakle Pierre Abinakle, Managing Director, Head of Compliance 11/13/2025 CPP Investment Board Private Holdings (4) Inc. /s/ Pierre Abinakle Pierre Abinakle, Director 11/13/2025 99.1 Power of Attorney of Canada Pension Plan Investment Board (incorporated by reference to Exhibit 99.1 of the Schedule 13G/A filed by the reporting persons in respect of the issuer on March 6, 2025).