WAY

SEC source: 0001104659-25-059839 · tm2518062-2_4seq1.xml · nonDerivative · entry 1

DRISCOLL JOHN PATRICK · CIK 0001257287 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 90,757

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: 0001104659-25-059836 · tm2518062-1_4seq1.xml · nonDerivative · entry 1

Gupta Aashima · CIK 0001946262 · 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: 0001104659-25-058884 · tm2517879-3_4seq1.xml · nonDerivative · entry 1

Oreskovich Steven M · CIK 0001368470 · Chief Financial Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 368,550

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 $40.48 to $40.99, 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 September 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F3 · balance_after: Includes unvested RSU's.

SEC source: 0001104659-25-058881 · tm2517879-2_4seq1.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 192,484

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 $40.47 to $40.99, 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 20, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F3 · balance_after: Includes unvested RSU's.

SEC source: 0001104659-25-058877 · tm2517879-1_4seq1.xml · nonDerivative · entry 1

Bridge T. Craig · CIK 0001998332 · Chief Transformation Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 767,843

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 $40.47 to $40.99, 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 27, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F3 · balance_after: Includes unvested RSU's

SEC source: 0001104659-25-058579 · tm2517745-2_4seq1.xml · derivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 120,732

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: 0001104659-25-058579 · tm2517745-2_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 $40.335 to $41.05, 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: 0001104659-25-058579 · tm2517745-2_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: 0001104659-25-058576 · tm2517745-1_4seq1.xml · derivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,226,214

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.

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: 0001104659-25-058576 · tm2517745-1_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 · 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 $40.13 to $41.07, 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: 0001104659-25-058576 · tm2517745-1_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: 0001998251-25-000006 · wk-form4_1756414968.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 193,261

F1 · balance_after: This transaction was not timely filed. The transaction represents shares of common stock withheld to pay taxes upon vesting of Non-Qualified Stock Options granted to the Reporting Person on June 6, 2024. The number of shares withheld was determined on June 6, 2025, based on the closing price of WAY common stock on that date. In addition, the total number of shares beneficially owned following the reported transaction reflects a correction to prior filings to account for an earlier misclassification of an option exercise. The ending balance reported herein is accurate and reflects the Reporting Person's current holdings.

SEC source: 0002020858-25-000004 · wk-form4_1757372260.xml · nonDerivative · entry 1

Wittman Kimberly S. · CIK 0002020858 · Chief People Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 193,261

F1 · balance_after: This transaction was not timely filed. The transaction represents shares of common stock withheld to pay taxes upon vesting of Non-Qualified Stock Options granted to the Reporting Person on June 6, 2024. The number of shares withheld was determined on June 6, 2025, based on the closing price of WAY common stock on that date. In addition, the total number of shares beneficially owned following the reported transaction reflects a correction to prior filings to account for an earlier misclassification of an option exercise. The ending balance reported herein is accurate and reflects the Reporting Person's current holdings.

SEC source: 0001998332-25-000005 · wk-form4_1757526634.xml · nonDerivative · entry 1

Bridge T. Craig · CIK 0001998332 · Chief Transformation Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 668,355

F1 · balance_after: Includes unvested RSUs.

F2 · balance_after: This transaction was not timely filed. The transaction represents shares of common stock withheld to pay taxes upon vesting of Non-Qualified Stock Options granted to the Reporting Person on June 6, 2024. The number of shares withheld was determined on June 6, 2025, based on the closing price of WAY common stock on that date. In addition, the total number of shares beneficially owned following the reported transaction reflects a correction to prior filings to account for an earlier misclassification of an option exercise. The ending balance reported herein is accurate and reflects the Reporting Person's current holdings.

SEC source: 0001998250-25-000006 · wk-form4_1757526443.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 474,826

F1 · balance_after: Includes unvested RSUs.

F2 · balance_after: This transaction was not timely filed. The transaction represents shares of common stock withheld to pay taxes upon vesting of Non-Qualified Stock Options granted to the Reporting Person on June 6, 2024. The number of shares withheld was determined on June 6, 2025, based on the closing price of WAY common stock on that date. In addition, the total number of shares beneficially owned following the reported transaction reflects a correction to prior filings to account for an earlier misclassification of an option exercise. The ending balance reported herein is accurate and reflects the Reporting Person's current holdings.

SEC source: 0001368470-25-000007 · wk-form4_1757605343.xml · nonDerivative · entry 1

Oreskovich Steven M · CIK 0001368470 · Chief Financial Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 354,512

F1 · balance_after: This transaction was not timely filed. The transaction represents shares of common stock withheld to pay taxes upon vesting of Non-Qualified Stock Options granted to the Reporting Person on June 6, 2024. The number of shares withheld was determined on June 6, 2025, based on the closing price of WAY common stock on that date.

SEC source: 0001998333-25-000006 · wk-form4_1757605867.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 422,371

F1 · balance_after: This transaction was not timely filed. The transaction represents shares of common stock withheld to pay taxes upon vesting of Non-Qualified Stock Options granted to the Reporting Person on June 6, 2024. The number of shares withheld was determined on June 6, 2025, based on the closing price of WAY common stock on that date.

SEC source: 0001998256-25-000007 · wk-form4_1758733478.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 717,474

F1 · balance_after: Includes unvested RSUs.

F2 · balance_after: This transaction was not timely filed. The transaction represents shares of common stock withheld to pay taxes upon vesting of Non-Qualified Stock Options granted to the Reporting Person on June 6, 2024. The number of shares withheld was determined on June 6, 2025, based on the closing price of WAY common stock on that date. The ending balance reported herein is accurate and reflects the Reporting Person's current holdings.

SEC source: 0001104659-25-057293 · tm2517351-1_4seq1.xml · derivative · entry 3

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,272,881

Underlying: Common Stock · 59,836 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: 0001104659-25-057293 · tm2517351-1_4seq1.xml · nonDerivative · entry 2

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 764,131

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 $40.10 to $40.43, 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 pursuant to broker sales conducted in accordance with Rule 144 under the Securities Act of 1933, as amended.

SEC source: 0001104659-25-057293 · tm2517351-1_4seq1.xml · nonDerivative · entry 1

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 823,967

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.

SEC source: 0001104659-25-055422 · tm2516824-1_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: 135,820

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.

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

SEC source: 0001104659-25-055422 · tm2516824-1_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

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: 0001104659-25-055422 · tm2516824-1_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: 0001104659-25-053111 · tm2516256-1_4seq1.xml · derivative · entry 9

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,332,717

Underlying: Common Stock · 140,164 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: 0001104659-25-053111 · tm2516256-1_4seq1.xml · nonDerivative · entry 6

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 764,131

F4 · price: The price reported in Column 4 is a weighted average price. These shares of Common Stock of Issuer were sold in multiple transactions ranging from $38.7500 to $39.4800, 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: 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 $39.15 to $39.16, 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.

SEC source: 0001104659-25-053111 · tm2516256-1_4seq1.xml · nonDerivative · entry 5

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 904,295

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.

SEC source: 0001104659-25-053111 · tm2516256-1_4seq1.xml · derivative · entry 8

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,472,881

Underlying: Common Stock · 197,847 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: 0001104659-25-053111 · tm2516256-1_4seq1.xml · nonDerivative · entry 4

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 764,131

F3 · price: The price reported in Column 4 is a weighted average price. These shares of Common Stock of Issuer were sold in multiple transactions ranging from $38.37 to $38.6150, 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 pursuant to broker sales conducted in accordance with Rule 144 under the Securities Act of 1933, as amended.

SEC source: 0001104659-25-053111 · tm2516256-1_4seq1.xml · nonDerivative · entry 3

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 961,978

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.

SEC source: 0001104659-25-053111 · tm2516256-1_4seq1.xml · derivative · entry 7

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,670,728

Underlying: Common Stock · 2,153 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: 0001104659-25-053111 · tm2516256-1_4seq1.xml · nonDerivative · entry 2

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 76,413

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 $39.15 to $39.16, 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 pursuant to broker sales conducted in accordance with Rule 144 under the Securities Act of 1933, as amended.

SEC source: 0001104659-25-053111 · tm2516256-1_4seq1.xml · nonDerivative · entry 1

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 766,284

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.

SEC source: 0001104659-25-052088 · tm2515964-1_4seq1.xml · derivative · entry 4

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 145,522

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: 0001104659-25-052088 · tm2515964-1_4seq1.xml · nonDerivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 490,870

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).

F3 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-052088 · tm2515964-1_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: 490,907

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 $38.53 to $39.50, 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).

F3 · balance_after: Includes unvested RSUs.

SEC source: 0001104659-25-052088 · tm2515964-1_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).

F3 · balance_after: Includes unvested RSUs.

SEC source: 0000950170-25-075513 · ownership.xml · nonDerivative · entry 3

BAIN CAPITAL INVESTORS LLC · CIK 0001040508 · 10% owner

BCPE Derby Investor, LP · CIK 0002025342 · 10% owner

BCPE Derby GP, LLC · CIK 0002025234 · 10% owner

Bain Capital Fund XI, L.P. · CIK 0001568889 · 10% owner

Bain Capital Partners XI, L.P. · CIK 0001851748 · 10% owner

BCPE Derby (DE) SPV, LP · CIK 0002048434 · 10% owner

BCPE Derby (DE) SPV (GP), LLC · CIK 0002048242 · 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: 18,055,049

F5 · kind: In connection with the exercise of the underwriters' option to purchase additional shares of Common Stock in a registered public offering that closed on May 20, 2025, 65,295 shares of Common Stock were sold by Derby Investor and 386,542 shares of Common Stock were sold by Derby SPV Investor at a price of $37.3937 (net of underwriting discount).

F5 · price: In connection with the exercise of the underwriters' option to purchase additional shares of Common Stock in a registered public offering that closed on May 20, 2025, 65,295 shares of Common Stock were sold by Derby Investor and 386,542 shares of Common Stock were sold by Derby SPV Investor at a price of $37.3937 (net of underwriting discount).

F1 · ownership.nature: Bain Capital Investors, LLC ("BCI") is the manager of Bain Capital Partners XI, L.P. ("Partners XI"), which is the general partner of Bain Capital Fund XI, L.P. ("Fund XI"). Fund XI is the (i) sole member of BCPE Derby GP, LLC ("Derby GP"), which is the general partner of BCPE Derby Investor, LP ("Derby Investor") and (ii) sole member of BCPE Derby (DE) SPV, LLC ("Derby SPV GP"), which is the general partner of BCPE Derby (DE) SPV, LP ("Derby SPV Investor" and, together with BCI, Partners XI, Fund XI, Derby GP, Derby Investor and Derby SPV GP, the "Bain Capital Entities").

F2 · ownership.nature: (Continued from footnote 1) As a result, the Bain Capital Entities may be deemed to share voting and dispositive power with respect to the shares of the Issuer's common stock, par value $0.01 per share (the "Common Stock"), held by Derby Investor and Derby SPV Investor. The Bain Capital Entities disclaim beneficial ownership of such securities, except to the extent of their pecuniary interest therein.

SEC source: 0000950170-25-075495 · ownership.xml · nonDerivative · entry 3

Moskowitz Paul G · CIK 0001997404 · Director · 10% owner

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 18,055,049

F5 · kind: In connection with the exercise of the underwriters' option to purchase additional shares of Common Stock in a registered public offering that closed on May 20, 2025, 65,295 shares of Common Stock were sold by Derby Investor and 386,542 shares of Common Stock were sold by Derby SPV Investor at a price of $37.3937 (net of underwriting discount).

F5 · price: In connection with the exercise of the underwriters' option to purchase additional shares of Common Stock in a registered public offering that closed on May 20, 2025, 65,295 shares of Common Stock were sold by Derby Investor and 386,542 shares of Common Stock were sold by Derby SPV Investor at a price of $37.3937 (net of underwriting discount).

F1 · ownership.nature: Represents shares held by BCPE Derby Investor, LP ("Derby Investor") and BCPE Derby (DE) SPV, LP ("Derby SPV Investor"). Bain Capital Investors, LLC ("BCI") is the manager of Bain Capital Partners XI, L.P. ("Partners XI"), which is the general partner of Bain Capital Fund XI, L.P. ("Fund XI"). Fund XI is the (i) sole member of BCPE Derby GP, LLC ("Derby GP"), which is the general partner of Derby Investor and (ii) sole member of BCPE Derby (DE) SPV, LLC ("Derby SPV GP" and, together with BCI, Partners XI, Fund XI, Derby GP, Derby Investor and Derby SPV Investor, the "Bain Capital Entities"), which is the general partner of Derby SPV Investor.

F2 · ownership.nature: (Continued from footnote 1) Paul G Moskowitz, a member of the board of directors of Waystar Holding Corp. (the "Issuer"), is a Partner of BCI. By virtue of the relationships described in this footnote, Mr. Moskowitz may be deemed to share voting and dispositive power with respect to the shares of the Issuer's common stock, par value $0.01 per share (the "Common Stock"), held by the Bain Capital Entities. Mr. Moskowitz disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein.

SEC source: 0001104659-25-051037 · tm2515695-1_4seq1.xml · nonDerivative · entry 2

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: 24,964,225

F3 · price: This amount represents the $37.3937 sale price per share of Common Stock, par value $0.01 per share, in connection with the underwriters' exercise of their over-allotment option relating to the secondary offering, which closed on May 20, 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: 0000950170-25-075228 · ownership.xml · nonDerivative · entry 2

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: 32,645,525

F3 · price: This amount represents the $37.3937 sale price per share of Common Stock, par value $0.01 per share, in connection with the underwriters' exercise of their over-allotment option relating to the secondary offering, which closed on May 20, 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: 0000950170-25-075513 · ownership.xml · nonDerivative · entry 2

BAIN CAPITAL INVESTORS LLC · CIK 0001040508 · 10% owner

BCPE Derby Investor, LP · CIK 0002025342 · 10% owner

BCPE Derby GP, LLC · CIK 0002025234 · 10% owner

Bain Capital Fund XI, L.P. · CIK 0001568889 · 10% owner

Bain Capital Partners XI, L.P. · CIK 0001851748 · 10% owner

BCPE Derby (DE) SPV, LP · CIK 0002048434 · 10% owner

BCPE Derby (DE) SPV (GP), LLC · CIK 0002048242 · 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: 18,506,886

F4 · kind: On May 16, 2025, Derby Investor distributed 235,397 shares of Common Stock to one or more of its members or partners in connection with certain charitable gifts made by such members or partners or their direct or indirect owners.

F4 · price: On May 16, 2025, Derby Investor distributed 235,397 shares of Common Stock to one or more of its members or partners in connection with certain charitable gifts made by such members or partners or their direct or indirect owners.

F1 · ownership.nature: Bain Capital Investors, LLC ("BCI") is the manager of Bain Capital Partners XI, L.P. ("Partners XI"), which is the general partner of Bain Capital Fund XI, L.P. ("Fund XI"). Fund XI is the (i) sole member of BCPE Derby GP, LLC ("Derby GP"), which is the general partner of BCPE Derby Investor, LP ("Derby Investor") and (ii) sole member of BCPE Derby (DE) SPV, LLC ("Derby SPV GP"), which is the general partner of BCPE Derby (DE) SPV, LP ("Derby SPV Investor" and, together with BCI, Partners XI, Fund XI, Derby GP, Derby Investor and Derby SPV GP, the "Bain Capital Entities").

F2 · ownership.nature: (Continued from footnote 1) As a result, the Bain Capital Entities may be deemed to share voting and dispositive power with respect to the shares of the Issuer's common stock, par value $0.01 per share (the "Common Stock"), held by Derby Investor and Derby SPV Investor. The Bain Capital Entities disclaim beneficial ownership of such securities, except to the extent of their pecuniary interest therein.

SEC source: 0000950170-25-075513 · ownership.xml · nonDerivative · entry 1

BAIN CAPITAL INVESTORS LLC · CIK 0001040508 · 10% owner

BCPE Derby Investor, LP · CIK 0002025342 · 10% owner

BCPE Derby GP, LLC · CIK 0002025234 · 10% owner

Bain Capital Fund XI, L.P. · CIK 0001568889 · 10% owner

Bain Capital Partners XI, L.P. · CIK 0001851748 · 10% owner

BCPE Derby (DE) SPV, LP · CIK 0002048434 · 10% owner

BCPE Derby (DE) SPV (GP), LLC · CIK 0002048242 · 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: 18,742,283

F3 · kind: Pursuant to a registered public offering that closed on May 16, 2025, 233,925 shares of Common Stock were sold by Derby Investor and 2,778,328 shares of Common Stock were sold by Derby SPV Investor at a price of $37.3937 (net of underwriting discount).

F3 · price: Pursuant to a registered public offering that closed on May 16, 2025, 233,925 shares of Common Stock were sold by Derby Investor and 2,778,328 shares of Common Stock were sold by Derby SPV Investor at a price of $37.3937 (net of underwriting discount).

F1 · ownership.nature: Bain Capital Investors, LLC ("BCI") is the manager of Bain Capital Partners XI, L.P. ("Partners XI"), which is the general partner of Bain Capital Fund XI, L.P. ("Fund XI"). Fund XI is the (i) sole member of BCPE Derby GP, LLC ("Derby GP"), which is the general partner of BCPE Derby Investor, LP ("Derby Investor") and (ii) sole member of BCPE Derby (DE) SPV, LLC ("Derby SPV GP"), which is the general partner of BCPE Derby (DE) SPV, LP ("Derby SPV Investor" and, together with BCI, Partners XI, Fund XI, Derby GP, Derby Investor and Derby SPV GP, the "Bain Capital Entities").

F2 · ownership.nature: (Continued from footnote 1) As a result, the Bain Capital Entities may be deemed to share voting and dispositive power with respect to the shares of the Issuer's common stock, par value $0.01 per share (the "Common Stock"), held by Derby Investor and Derby SPV Investor. The Bain Capital Entities disclaim beneficial ownership of such securities, except to the extent of their pecuniary interest therein.

SEC source: 0000950170-25-075495 · ownership.xml · nonDerivative · entry 2

Moskowitz Paul G · CIK 0001997404 · Director · 10% owner

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 18,506,886

F4 · kind: On May 16, 2025, Derby Investor distributed 235,397 shares of Common Stock to one or more of its members or partners in connection with certain charitable gifts made by such members or partners or their direct or indirect owners.

F4 · price: On May 16, 2025, Derby Investor distributed 235,397 shares of Common Stock to one or more of its members or partners in connection with certain charitable gifts made by such members or partners or their direct or indirect owners.

F1 · ownership.nature: Represents shares held by BCPE Derby Investor, LP ("Derby Investor") and BCPE Derby (DE) SPV, LP ("Derby SPV Investor"). Bain Capital Investors, LLC ("BCI") is the manager of Bain Capital Partners XI, L.P. ("Partners XI"), which is the general partner of Bain Capital Fund XI, L.P. ("Fund XI"). Fund XI is the (i) sole member of BCPE Derby GP, LLC ("Derby GP"), which is the general partner of Derby Investor and (ii) sole member of BCPE Derby (DE) SPV, LLC ("Derby SPV GP" and, together with BCI, Partners XI, Fund XI, Derby GP, Derby Investor and Derby SPV Investor, the "Bain Capital Entities"), which is the general partner of Derby SPV Investor.

F2 · ownership.nature: (Continued from footnote 1) Paul G Moskowitz, a member of the board of directors of Waystar Holding Corp. (the "Issuer"), is a Partner of BCI. By virtue of the relationships described in this footnote, Mr. Moskowitz may be deemed to share voting and dispositive power with respect to the shares of the Issuer's common stock, par value $0.01 per share (the "Common Stock"), held by the Bain Capital Entities. Mr. Moskowitz disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein.

SEC source: 0000950170-25-075495 · ownership.xml · nonDerivative · entry 1

Moskowitz Paul G · CIK 0001997404 · Director · 10% owner

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 18,742,283

F3 · kind: Pursuant to a registered public offering that closed on May 16, 2025, 233,925 shares of Common Stock were sold by Derby Investor and 2,778,328 shares of Common Stock were sold by Derby SPV Investor at a price of $37.3937 (net of underwriting discount).

F3 · price: Pursuant to a registered public offering that closed on May 16, 2025, 233,925 shares of Common Stock were sold by Derby Investor and 2,778,328 shares of Common Stock were sold by Derby SPV Investor at a price of $37.3937 (net of underwriting discount).

F1 · ownership.nature: Represents shares held by BCPE Derby Investor, LP ("Derby Investor") and BCPE Derby (DE) SPV, LP ("Derby SPV Investor"). Bain Capital Investors, LLC ("BCI") is the manager of Bain Capital Partners XI, L.P. ("Partners XI"), which is the general partner of Bain Capital Fund XI, L.P. ("Fund XI"). Fund XI is the (i) sole member of BCPE Derby GP, LLC ("Derby GP"), which is the general partner of Derby Investor and (ii) sole member of BCPE Derby (DE) SPV, LLC ("Derby SPV GP" and, together with BCI, Partners XI, Fund XI, Derby GP, Derby Investor and Derby SPV Investor, the "Bain Capital Entities"), which is the general partner of Derby SPV Investor.

F2 · ownership.nature: (Continued from footnote 1) Paul G Moskowitz, a member of the board of directors of Waystar Holding Corp. (the "Issuer"), is a Partner of BCI. By virtue of the relationships described in this footnote, Mr. Moskowitz may be deemed to share voting and dispositive power with respect to the shares of the Issuer's common stock, par value $0.01 per share (the "Common Stock"), held by the Bain Capital Entities. Mr. Moskowitz disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein.

SEC source: 0001104659-25-051037 · tm2515695-1_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: 25,580,929

F1 · price: This amount represents the $37.3937 sale price per share of Common Stock, par value $0.01 per share, in a secondary offering, which closed on May 16, 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: 0000950170-25-075228 · 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: 33,451,984

F1 · price: This amount represents the $37.3937 sale price per share of Common Stock, par value $0.01 per share, in a secondary offering, which closed on May 16, 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: 0001104659-25-049882 · tm2515316-1_4seq1.xml · nonDerivative · entry 2

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 198,556

F1 · 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: 0001104659-25-049882 · tm2515316-1_4seq1.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 198,656

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 $38.89 to $39.45, 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 20, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F3 · balance_after: Includes unvested RSUs.

SEC source: 0001998251-25-000004 · wk-form4a_1756414855.xml · derivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 35,550

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.

F1 · kind: This Form 4/A is being filed to correct the original Form 4 filed on May 15, 2025 ("Original Form 4"). The Original Form 4 inadvertently omitted the reporting of an option exercise that occurred on May 15, 2025, immediately prior to the sale of shares reported in that filing. The number of shares sold as reported in the Original Form 4 was correct; however, the ending total was incorrect due to the omission of the option exercise. This amendment adds the previously unreported option exercise transaction and restates the sell of shares reported in the Original Form 4 in a single combined row, consistent with other filings for the Reporting Owner. No other changes have been made to the Original Form 4.

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).