WAY

SEC source: 0002020858-26-000002 · wk-form4_1773269053.xml · nonDerivative · entry 1

Wittman Kimberly S. · CIK 0002020858 · Chief People Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 272,964

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vests in four equal annual installments from the initial grant date through March 1, 2030. 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: 0001998251-26-000002 · wk-form4_1773269097.xml · nonDerivative · entry 1

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 254,964

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vests in four equal annual installments from the initial grant date through March 1, 2030. 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: 0001735839-26-000002 · wk-form4_1773268912.xml · nonDerivative · entry 1

PACKER GREGORY R · CIK 0001735839 · Chief Legal officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 196,964

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vests in four equal annual installments from the initial grant date through March 1, 2030. 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: 0001998332-26-000002 · wk-form4_1773268831.xml · nonDerivative · entry 1

Bridge T. Craig · CIK 0001998332 · Chief Transformation Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 670,768

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vests in four equal annual installments from the initial grant date through March 1, 2030. 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: 0001368470-26-000002 · wk-form4_1773268666.xml · nonDerivative · entry 1

Oreskovich Steven M · CIK 0001368470 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 436,783

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vests in four equal annual installments from the initial grant date through March 1, 2030. 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: 0001998333-26-000002 · wk-form4_1773268720.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 509,784

F1 · shares: Reflects a grant of restricted stock units ("RSUs") which vests in four equal annual installments from the initial grant date through March 1, 2030. 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: 0001998256-26-000002 · wk-form4_1773268608.xml · nonDerivative · entry 1

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 974,570

F1 · kind: Reflects a grant of restricted stock units ("RSUs") which vests in four equal annual installments from the initial grant date through March 1, 2030. 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: 0001199930-26-000002 · wk-form4_1772572333.xml · nonDerivative · entry 1

MILLER HEIDI · CIK 0001199930 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By Family Trusts

Disclosed balance after: 7,200

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 purchased in multiple transactions ranging from $26.247 to $26.248 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: 0001998250-26-000002 · wk-form4_1769116455.xml · derivative · entry 5

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 6,141

Underlying: Common Stock · 32,663 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: 0001998250-26-000002 · wk-form4_1769116455.xml · derivative · entry 4

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 173,938

Underlying: Common Stock · 7,562 shares

Expires 2030-08-09

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: 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.

SEC source: 0001998250-26-000002 · wk-form4_1769116455.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

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 $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.

F1 · balance_after: Includes unvested RSUs.

F2 · balance_after: 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).

SEC source: 0001998250-26-000002 · wk-form4_1769116455.xml · nonDerivative · entry 2

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 515,051

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.

F2 · balance_after: 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).

SEC source: 0001998250-26-000002 · wk-form4_1769116455.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 482,388

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.

F2 · balance_after: 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).

SEC source: 0001998250-25-000015 · wk-form4_1766507528.xml · derivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 38,804

Underlying: Common Stock · 9,701 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: 0001998250-25-000015 · wk-form4_1766507528.xml · nonDerivative · entry 2

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 474,826

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 $32.57 to $32.98, 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.

F2 · 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: 0001998250-25-000015 · wk-form4_1766507528.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 484,527

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.

F2 · 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: 0001998333-25-000013 · wk-form4_1765469358.xml · derivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 68,994

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: 0001998333-25-000013 · wk-form4_1765469358.xml · nonDerivative · entry 2

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 422,371

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).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998333-25-000013 · wk-form4_1765469358.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

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.

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).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998251-25-000009 · wk-form4_1764169966.xml · derivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 28,750

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.

F3 · 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.

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).

SEC source: 0001998251-25-000009 · wk-form4_1764169966.xml · nonDerivative · entry 2

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 193,261

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).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998251-25-000009 · wk-form4_1764169966.xml · nonDerivative · entry 1

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.

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).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998250-25-000013 · wk-form4_1763740888.xml · derivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 48,505

Underlying: Common Stock · 9,701 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: 0001998250-25-000013 · wk-form4_1763740888.xml · nonDerivative · entry 2

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 474,826

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 $34.79 to $35.80, 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: Includes unvested RSUs.

F2 · 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: 0001998250-25-000013 · wk-form4_1763740888.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 484,527

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.

F2 · 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: 0001998333-25-000011 · wk-form4_1762967662.xml · derivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 77,617

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.

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

SEC source: 0001998333-25-000011 · wk-form4_1762967662.xml · nonDerivative · entry 2

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 422,371

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 $35.63 to $36.50, 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 December 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998333-25-000011 · wk-form4_1762967662.xml · nonDerivative · entry 1

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.

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).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998250-25-000011 · wk-form4_1761077378.xml · derivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,206

Underlying: Common Stock · 9,701 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: 0001998250-25-000011 · wk-form4_1761077378.xml · nonDerivative · entry 2

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 474,826

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 $36.52 to $37.86, 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.

F2 · 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: 0001998250-25-000011 · wk-form4_1761077378.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 484,527

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.

F2 · 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: 0001998256-25-000009 · wk-form4_1760967653.xml · derivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,264,545

Underlying: Common Stock · 200 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: 0001998256-25-000009 · wk-form4_1760967653.xml · nonDerivative · entry 2

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: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on June 6, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998256-25-000009 · wk-form4_1760967653.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 717,674

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.

F2 · balance_after: These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on June 6, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998333-25-000009 · wk-form4_1760452820.xml · derivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 86,240

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.

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

SEC source: 0001998333-25-000009 · wk-form4_1760452820.xml · nonDerivative · entry 2

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 422,371

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 $35.66 to $37.22, 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: 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).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998333-25-000009 · wk-form4_1760452820.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

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.

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).

F2 · balance_after: Includes unvested RSUs.

SEC source: 0001998256-25-000007 · wk-form4_1758733478.xml · derivative · entry 7

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,264,745

Underlying: Common Stock · 12,800 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.

F6 · derivative.exercise_date: These options are currently vested.

SEC source: 0001998256-25-000007 · wk-form4_1758733478.xml · nonDerivative · entry 5

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 717,474

F5 · 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 $38.00 to $38.16, 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: 0001998256-25-000007 · wk-form4_1758733478.xml · nonDerivative · entry 4

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 730,274

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 June 6, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998256-25-000007 · wk-form4_1758733478.xml · derivative · entry 6

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,277,545

Underlying: Common Stock · 12,200 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.

F6 · derivative.exercise_date: These options are currently vested.

SEC source: 0001998256-25-000007 · wk-form4_1758733478.xml · nonDerivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 717,474

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 $38.00 to $38.20, 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 June 6, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998256-25-000007 · wk-form4_1758733478.xml · nonDerivative · entry 2

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 729,674

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 June 6, 2025 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001998250-25-000008 · wk-form4_1758733435.xml · derivative · entry 3

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 67,907

Underlying: Common Stock · 9,701 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: 0001998250-25-000008 · wk-form4_1758733435.xml · nonDerivative · entry 2

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 474,826

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 $37.24 to $38.14, 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.

F2 · 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: 0001998250-25-000008 · wk-form4_1758733435.xml · nonDerivative · entry 1

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 484,527

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.

F2 · 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: 0001193125-25-205034 · 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: 13,243,539

F4 · kind: On September 12, 2025, Derby Investor distributed 397,013 shares of Common Stock and Derby SPV Investor distributed 119,358 shares of Common Stock to one or more of their respective members or partners in connection with certain charitable gifts made by such members or partners or their direct or indirect owners. Such shares of Common Stock are subject to lock-up agreements that, subject to certain exceptions, restrict the sale of such shares until November 11, 2025 except with the prior written consent of J.P. Morgan Securities LLC.

F4 · price: On September 12, 2025, Derby Investor distributed 397,013 shares of Common Stock and Derby SPV Investor distributed 119,358 shares of Common Stock to one or more of their respective members or partners in connection with certain charitable gifts made by such members or partners or their direct or indirect owners. Such shares of Common Stock are subject to lock-up agreements that, subject to certain exceptions, restrict the sale of such shares until November 11, 2025 except with the prior written consent of J.P. Morgan Securities LLC.

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: 0001193125-25-205034 · 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: 13,759,910

F3 · kind: Pursuant to a registered public offering that closed on September 12, 2025, 298,303 shares of Common Stock were sold by Derby Investor and 3,996,836 shares of Common Stock were sold by Derby SPV Investor at a price of $39.21 (net of underwriting discount).

F3 · price: Pursuant to a registered public offering that closed on September 12, 2025, 298,303 shares of Common Stock were sold by Derby Investor and 3,996,836 shares of Common Stock were sold by Derby SPV Investor at a price of $39.21 (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: 0000950130-25-000135 · 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: 13,243,539

F4 · kind: On September 12, 2025, Derby Investor distributed 397,013 shares of Common Stock and Derby SPV Investor distributed 119,358 shares of Common Stock to one or more of their respective members or partners in connection with certain charitable gifts made by such members or partners or their direct or indirect owners. Such shares of Common Stock are subject to lock-up agreements that, subject to certain exceptions, restrict the sale of such shares until November 11, 2025 except with the prior written consent of J.P. Morgan Securities LLC.

F4 · price: On September 12, 2025, Derby Investor distributed 397,013 shares of Common Stock and Derby SPV Investor distributed 119,358 shares of Common Stock to one or more of their respective members or partners in connection with certain charitable gifts made by such members or partners or their direct or indirect owners. Such shares of Common Stock are subject to lock-up agreements that, subject to certain exceptions, restrict the sale of such shares until November 11, 2025 except with the prior written consent of J.P. Morgan Securities LLC.

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: 0000950130-25-000135 · 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: 13,759,910

F3 · kind: Pursuant to a registered public offering that closed on September 12, 2025, 298,303 shares of Common Stock were sold by Derby Investor and 3,996,836 shares of Common Stock were sold by Derby SPV Investor at a price of $39.21 (net of underwriting discount).

F3 · price: Pursuant to a registered public offering that closed on September 12, 2025, 298,303 shares of Common Stock were sold by Derby Investor and 3,996,836 shares of Common Stock were sold by Derby SPV Investor at a price of $39.21 (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.