WAY

SEC source: 0001193125-25-205033 · ownership.xml · nonDerivative · entry 1

Derby LuxCo S.a r.l. · CIK 0001998443 · 10% owner

EQT Fund Management S.a r.l. · CIK 0001834239 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Held directly by Derby LuxCo

Disclosed balance after: 24,879,437

F1 · price: This amount represents the $39.21 sale price per share of Common Stock, par value $0.01 per share, in a secondary offering, which closed on September 12, 2025.

F2 · ownership.nature: Consists of shares of common stock held directly by Derby LuxCo S.a r.l. ("Derby LuxCo"). Several investment vehicles collectively make up the fund known as "EQT VIII." EQT VIII owns 100% of the membership interests in Derby LuxCo. EQT Fund Management S.a r.l. ("EFMS") has exclusive responsibility for the management and control of the business and affairs of investment vehicles which constitute the majority of the total commitments to EQT VIII. EFMS is overseen by a board of not less than three individuals that acts by majority approval.

SEC source: 0001104659-25-090429 · tm2526226-1_4seq1.xml · nonDerivative · entry 1

CANADA PENSION PLAN INVESTMENT BOARD · CIK 0001283718 · 10% owner

CPP Investment Board Private Holdings (4) Inc. · CIK 0001978825 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnote

Disclosed balance after: 19,025,452

F1 · price: This amount represents the $39.21 sale price per share of Common Stock, par value $0.01 per share, in a secondary offering, which closed on September 12, 2025.

F2 · ownership.nature: The securities reported herein are held directly by CPP Investment Board Private Holdings (4) Inc. ("Holdings (4)"), a wholly-owned subsidiary of Canada Pension Plan Investment Board ("CPPIB"). CPPIB is an indirect beneficial owner of such securities directly held by Holdings (4).

SEC source: 0001368470-25-000007 · wk-form4_1757605343.xml · derivative · entry 4

Oreskovich Steven M · CIK 0001368470 · Chief Financial Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 101,205

Underlying: Common Stock · 16,666 shares

Expires 2028-09-17

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: These options are currently vested.

SEC source: 0001368470-25-000007 · wk-form4_1757605343.xml · nonDerivative · entry 3

Oreskovich Steven M · CIK 0001368470 · Chief Financial Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 354,512

F4 · price: 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 $40.09 to $40.90, 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.

F2 · balance_after: Includes unvested RSUs.

F3 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on September 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001368470-25-000007 · wk-form4_1757605343.xml · nonDerivative · entry 2

Oreskovich Steven M · CIK 0001368470 · Chief Financial Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 371,178

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · balance_after: Includes unvested RSUs.

F3 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on September 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998333-25-000006 · wk-form4_1757605867.xml · derivative · entry 4

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 94,863

Underlying: Common Stock · 8,623 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: These options are currently vested.

SEC source: 0001998333-25-000006 · wk-form4_1757605867.xml · nonDerivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 422,371

F4 · price: 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 $40.10 to $40.87, 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.

F2 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on December 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F3 · balance_after: Includes unvested RSUs.

SEC source: 0001998333-25-000006 · wk-form4_1757605867.xml · nonDerivative · entry 2

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 430,994

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on December 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F3 · balance_after: Includes unvested RSUs.

SEC source: 0001998332-25-000005 · wk-form4_1757526634.xml · nonDerivative · entry 2

Bridge T. Craig · CIK 0001998332 · Chief Transformation Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 583,355

F3 · price: 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 $40.00 to $40.22, 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.

F1 · balance_after: Includes unvested RSUs.

F4 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 27, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998250-25-000006 · wk-form4_1757526443.xml · derivative · entry 4

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 77,608

Underlying: Common Stock · 19,404 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: These options are currently vested.

SEC source: 0001998250-25-000006 · wk-form4_1757526443.xml · nonDerivative · entry 3

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 474,826

F4 · price: 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 $40.00 to $40.25, 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.

F1 · balance_after: Includes unvested RSUs.

F3 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998250-25-000006 · wk-form4_1757526443.xml · nonDerivative · entry 2

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 494,230

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes unvested RSUs.

F3 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0002020858-25-000004 · wk-form4_1757372260.xml · derivative · entry 3

Wittman Kimberly S. · CIK 0002020858 · Chief People Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 90,695

Underlying: Common Stock · 18,000 shares

Expires 2034-06-06

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: Options granted June 6, 2024, which vest in five equal annual installments commencing on June 6, 2025.

SEC source: 0002020858-25-000004 · wk-form4_1757372260.xml · nonDerivative · entry 2

Wittman Kimberly S. · CIK 0002020858 · Chief People Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 211,261

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998251-25-000006 · wk-form4_1756414968.xml · derivative · entry 4

Miller Melissa F. (Missy) · CIK 0001998251 · Chief Marketing Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 32,150

Underlying: Common Stock · 3,400 shares

Expires 2030-08-17

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: Options granted August 17, 2020 of which 50% of the option vests in five substantially equal annual installments commencing on August 17, 2021 and the remaining 50% of the option vests upon achievement of certain specified performance-based vesting criteria.

F2 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 20, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998251-25-000006 · wk-form4_1756414968.xml · nonDerivative · entry 3

Miller Melissa F. (Missy) · CIK 0001998251 · Chief Marketing Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 193,261

F4 · price: 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 $37.00 to $37.03, 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.

F2 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 20, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F3 · balance_after: Includes unvested RSUs.

SEC source: 0001998251-25-000006 · wk-form4_1756414968.xml · nonDerivative · entry 2

Miller Melissa F. (Missy) · CIK 0001998251 · Chief Marketing Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 196,661

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 20, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F3 · balance_after: Includes unvested RSUs.

SEC source: 0001998250-25-000004 · wk-form4_1755724162.xml · derivative · entry 3

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 97,012

Underlying: Common Stock · 9,702 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: These options are currently vested.

SEC source: 0001998250-25-000004 · wk-form4_1755724162.xml · nonDerivative · entry 2

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 490,870

F3 · price: 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 $34.73 to $35.28, 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.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998250-25-000004 · wk-form4_1755724162.xml · nonDerivative · entry 1

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 500,572

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001735839-25-000003 · wk-form4_1755641459.xml · nonDerivative · entry 1

PACKER GREGORY R · CIK 0001735839 · Chief Legal officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 131,147

F1 · acquired: Reflects a grant of restricted stock units ("RSUs") which vest over 4 years, with 40% vesting in year 3 and 60% vesting in year 4. Each RSU represents a contingent right to receive one share of common stock, $0.01 par value per share (the "Common Stock") upon settlement.

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998256-25-000005 · wk-form4_1755035011.xml · derivative · entry 3

Hawkins Matthew J. · CIK 0001998256 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,289,745

Underlying: Common Stock · 46,667 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: These options are currently vested.

SEC source: 0001998256-25-000005 · wk-form4_1755035011.xml · nonDerivative · entry 2

Hawkins Matthew J. · CIK 0001998256 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 764,131

F2 · price: 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 $34.44 to $34.89, 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.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 22, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998256-25-000005 · wk-form4_1755035011.xml · nonDerivative · entry 1

Hawkins Matthew J. · CIK 0001998256 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 810,798

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 22, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998333-25-000004 · wk-form4_1755034683.xml · derivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 103,486

Underlying: Common Stock · 8,623 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: These options are currently vested.

SEC source: 0001998333-25-000004 · wk-form4_1755034683.xml · nonDerivative · entry 2

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 438,044

F2 · price: 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 $34.28 to $34.80, 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.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on December 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998333-25-000004 · wk-form4_1755034683.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 446,667

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on December 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998256-25-000003 · wk-form4_1754090270.xml · derivative · entry 2

Hawkins Matthew J. · CIK 0001998256 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,336,412

Underlying: Common Stock · 156,865 shares

Expires 2027-11-01

F1 · derivative.exercise_date: These options are currently vested.

F2 · balance_after: Options previously reported as indirectly owned through a grantor retained annuity trust of which the reporting person is beneficiary were transferred to the reporting person directly. This transaction represents a change in the form of ownership from indirect to direct, with no change in the reporting person's pecuniary interest in the securities.

SEC source: 0001998256-25-000003 · wk-form4_1754090270.xml · derivative · entry 1

Hawkins Matthew J. · CIK 0001998256 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Indirect · By 2024 grantor retained annuity trust

Disclosed balance after: 343,135

Underlying: Common Stock · 156,865 shares

Expires 2027-11-01

F1 · derivative.exercise_date: These options are currently vested.

F2 · balance_after: Options previously reported as indirectly owned through a grantor retained annuity trust of which the reporting person is beneficiary were transferred to the reporting person directly. This transaction represents a change in the form of ownership from indirect to direct, with no change in the reporting person's pecuniary interest in the securities.

SEC source: 0001998250-25-000001 · wk-form4_1753225425.xml · derivative · entry 3

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 106,714

Underlying: Common Stock · 9,702 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: These options are currently vested.

SEC source: 0001998250-25-000001 · wk-form4_1753225425.xml · nonDerivative · entry 2

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 490,870

F3 · price: 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 $36.41 to $37.42, 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.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998250-25-000001 · wk-form4_1753225425.xml · nonDerivative · entry 1

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 500,572

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998332-25-000001 · wk-form4_1753225336.xml · nonDerivative · entry 1

Bridge T. Craig · CIK 0001998332 · Chief Transformation Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 682,843

F1 · price: 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 $36.36 to $37.42, 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.

F2 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 27, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F3 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-068318 · tm2521026-1_4seq1.xml · derivative · entry 3

Hawkins Matthew J. · CIK 0001998256 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,179,547

Underlying: Common Stock · 46,667 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: These options are currently vested.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 22, 2024, that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001104659-25-068318 · tm2521026-1_4seq1.xml · nonDerivative · entry 2

Hawkins Matthew J. · CIK 0001998256 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 764,131

F2 · shares: This footnote notes a correction and clerical error in the number of securities reported in Table I, Column 4 of a Form 4 filed on June 11, 2025 (the "Prior Form 4") for the Reporting Person, which incorrectly stated the number of securities sold as 2,704 instead of 46,667. All other aspects of the Prior Form 4, including the total number of securities beneficially owned following the reported transaction, as shown in Column 5, were correctly reported in the Prior Form 4.

F3 · price: 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 $37.8000 to $38.5600, 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.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 22, 2024, that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001104659-25-068318 · tm2521026-1_4seq1.xml · nonDerivative · entry 1

Hawkins Matthew J. · CIK 0001998256 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 810,798

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on November 22, 2024, that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001104659-25-067392 · tm2520683-1_4seq1.xml · derivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 112,109

Underlying: Common Stock · 8,623 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: These options are currently vested.

SEC source: 0001104659-25-067392 · tm2520683-1_4seq1.xml · nonDerivative · entry 2

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 438,044

F2 · price: 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 $37.2100 to $37.9900, 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.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on December 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001104659-25-067392 · tm2520683-1_4seq1.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 446,667

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on December 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001104659-25-062657 · tm2519025-1_4seq1.xml · derivative · entry 3

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 116,416

Underlying: Common Stock · 9,702 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: These options are currently vested.

SEC source: 0001104659-25-062657 · tm2519025-1_4seq1.xml · nonDerivative · entry 2

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 490,870

F3 · price: 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 $40.00 to $40.4050, 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.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-062657 · tm2519025-1_4seq1.xml · nonDerivative · entry 1

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 500,572

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-061662 · tm2518589-1_4seq1.xml · derivative · entry 3

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 126,118

Underlying: Common Stock · 9,702 shares

Expires 2027-11-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: These options are currently vested.

SEC source: 0001104659-25-061662 · tm2518589-1_4seq1.xml · nonDerivative · entry 2

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 490,870

F3 · price: 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 $37.65 to $38.09, 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.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-061662 · tm2518589-1_4seq1.xml · nonDerivative · entry 1

Sinclair III Eric L. (Ric) · CIK 0001998250 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 500,572

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on February 19, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-059860 · tm2518062-7_4seq1.xml · nonDerivative · entry 1

Hung Priscilla · CIK 0001557593 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,829

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 4, 2026 and (ii) the first regularly scheduled annual meeting of the stockholders following the grant date. Each RSU represents a contingent right to receive one share of Common Stock upon settlement.

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-059857 · tm2518062-6_4seq1.xml · nonDerivative · entry 1

MILLER HEIDI · CIK 0001199930 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 31,614

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 4, 2026 and (ii) the first regularly scheduled annual meeting of the stockholders following the grant date. Each RSU represents a contingent right to receive one share of Common Stock upon settlement.

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-059852 · tm2518062-5_4seq1.xml · nonDerivative · entry 1

Riefberg Vivian E. · CIK 0001843139 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,829

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 4, 2026 and (ii) the first regularly scheduled annual meeting of the stockholders following the grant date. Each RSU represents a contingent right to receive one share of Common Stock upon settlement.

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-059850 · tm2518062-4_4seq1.xml · nonDerivative · entry 1

Roman Michael F · CIK 0001577544 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 5,134

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 4, 2026 and (ii) the first regularly scheduled annual meeting of the stockholders following the grant date. Each RSU represents a contingent right to receive one share of Common Stock upon settlement.

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-059843 · tm2518062-3_4seq1.xml · nonDerivative · entry 1

DeMichiei Robert · CIK 0001928634 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 36,896

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 4, 2026 and (ii) the first regularly scheduled annual meeting of the stockholders following the grant date. Each RSU represents a contingent right to receive one share of Common Stock upon settlement.

F2 · balance_after: Includes unvested RSUs.