Schremser Christopher L.

SEC source: 0001998333-26-000004 · wk-form4_1781038770.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 495,033

F1 · balance_after: 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 based on the actual sale price of shares sold on June 9, 2026 pursuant to a sell-to-cover transaction.

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: 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: 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: 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: 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: 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: 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: 0001104659-25-058579 · 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: 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: 0001104659-25-047354 · tm2514848-1_4seq1.xml · derivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 129,355

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.

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: 0001104659-25-047354 · tm2514848-1_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 $39.97 to $40.58, 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: 0001104659-25-047354 · tm2514848-1_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: 0001104659-25-034705 · tm2512190-2_4seq1.xml · derivative · entry 4

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 137,978

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.

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: 0001104659-25-034705 · tm2512190-2_4seq1.xml · nonDerivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 438,044

F3 · price: The price reported in Column 4 is a weighted average price. These shares of Common Stock of the Issuer were sold in multiple transactions ranging from $36.63 to $37.05, 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: 0001104659-25-034705 · tm2512190-2_4seq1.xml · nonDerivative · entry 2

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 440,557

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 $35.63 to $36.62, 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: 0001104659-25-034705 · tm2512190-2_4seq1.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

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: 0001104659-25-031494 · tm2511308-6_4seq1.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 438,044

F1 · kind: 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: 0001104659-25-022577 · tm258784-1_4seq1.xml · derivative · entry 8

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 146,601

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.

F7 · 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 December 6, 2024 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

SEC source: 0001104659-25-022577 · tm258784-1_4seq1.xml · nonDerivative · entry 7

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 173,913

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: 0001104659-25-022577 · tm258784-1_4seq1.xml · nonDerivative · entry 6

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 174,013

F6 · price: The price reported in Column 4 is a weighted average price. These shares of Common Stock of the Issuer were sold in multiple transactions ranging from $39.54 to $40.49, 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: 0001104659-25-022577 · tm258784-1_4seq1.xml · nonDerivative · entry 5

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 174,913

F5 · price: The price reported in Column 4 is a weighted average price. These shares of Common Stock of the Issuer were sold in multiple transactions ranging from $38.54 to $39.00, 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: 0001104659-25-022577 · tm258784-1_4seq1.xml · nonDerivative · entry 4

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 175,213

F4 · price: The price reported in Column 4 is a weighted average price. These shares of Common Stock of the Issuer were sold in multiple transactions ranging from $37.27 to $37.69, 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: 0001104659-25-022577 · tm258784-1_4seq1.xml · nonDerivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 178,785

F3 · price: The price reported in Column 4 is a weighted average price. These shares of Common Stock of the Issuer were sold in multiple transactions ranging from $36.25 to $37.24, 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: 0001104659-25-022577 · tm258784-1_4seq1.xml · nonDerivative · entry 2

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 180,972

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 $35.23 to $36.15, 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: 0001104659-25-022577 · tm258784-1_4seq1.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 182,536

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: 0001104659-24-070870 · tm2416795-3_4seq1.xml · nonDerivative · entry 1

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 173,913

F1 · kind: Reflects a grant of restricted stock units ("RSUs") which vest in five substantially equal annual installments commencing on June 6, 2025. 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: 0001104659-24-070870 · tm2416795-3_4seq1.xml · derivative · entry 3

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 434,782

Underlying: Common Stock · 434,782 shares

Expires 2034-06-06

F4 · derivative.exercise_date: On June 6, 2024 reporting person was granted options to purchase shares of Common Stock which vest in five substantially equal annual installments commencing on June 6, 2025. Such securities were originally included on the Form 3 filed by the reporting person on June 7, 2024.

SEC source: 0001104659-24-070870 · tm2416795-3_4seq1.xml · derivative · entry 2

Schremser Christopher L. · CIK 0001998333 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 72,600

Underlying: Common Stock · 72,600 shares

Expires 2034-05-01

F3 · kind: On May 1, 2024 reporting person was granted options to purchase shares of Common Stock which vest in three substantially equal annual installments commencing on May 1, 2025. Such securities were originally included on the Form 3 filed by the reporting person on June 7, 2024. Reflects the 0.605-for-1 reverse stock split which became effective on May 15, 2024.

F3 · derivative.exercise_date: On May 1, 2024 reporting person was granted options to purchase shares of Common Stock which vest in three substantially equal annual installments commencing on May 1, 2025. Such securities were originally included on the Form 3 filed by the reporting person on June 7, 2024. Reflects the 0.605-for-1 reverse stock split which became effective on May 15, 2024.