WAY · Waystar Holding Corp.

Includes unvested RSUs.

These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on March 13, 2026 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

These options are currently vested.

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 $25.00 to $25.05, 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.

Includes unvested RSUs.

These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on March 13, 2026 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

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 $25.00 to $25.08, 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.

Includes unvested RSUs.

These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on March 13, 2026 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

These options are currently vested.

Includes unvested RSUs.

These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on March 13, 2026 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Reflects a grant of restricted stock units ("RSUs") which vest over 2 years, with 12.5% vesting each quarter during year 1 and 50% vesting in year 2. Each RSU represents a contingent right to receive one share of common stock, $0.01 par value per share (the "Common Stock") upon settlement.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest over 2 years, with 12.5% vesting each quarter during year 1 and 50% vesting in year 2. Each RSU represents a contingent right to receive one share of common stock, $0.01 par value per share (the "Common Stock") upon settlement.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest in three equal annual installments from the initial grant date. Each RSU represents a contingent right to receive one share of common stock, $0.01 par value per share (the "Common Stock") upon settlement.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest over 2 years, with 12.5% vesting each quarter during year 1 and 50% vesting in year 2. Each RSU represents a contingent right to receive one share of common stock, $0.01 par value per share (the "Common Stock") upon settlement.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") awarded on July 24, 2026. Subject to the reporting person's continued service through the applicable vesting date, 6.25% of the RSUs vest quarterly during the first 12 months following the grant date, and 25% of the RSUs vest on each July 22 thereafter through July 22, 2030. Each RSU represents a contingent right to receive one share of common stock, par value $0.01 per share ("Common Stock"), upon settlement.

Includes unvested RSUs.

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 $23.00 to $23.27, 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.

Includes unvested RSUs.

These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on March 13, 2026 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Includes unvested RSUs.

These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on March 13, 2026 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

These options are currently vested.

These options are currently vested.

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 $23.00 to $23.08, 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.

Includes unvested RSUs.

These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on March 13, 2026 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Includes unvested RSUs.

These transactions occurred automatically pursuant to a plan adopted by the Reporting Person on March 13, 2026 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 1, 2027 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.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 1, 2027 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.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 1, 2027 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.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 1, 2027 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.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 1, 2027 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.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 1, 2027 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.

Includes unvested RSUs.

Reflects a grant of restricted stock units ("RSUs") which vest on the earlier of (i) June 1, 2027 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.

Includes unvested RSUs.

Includes unvested RSUs.

The transaction represents shares of common stock withheld to pay taxes upon vesting of restricted stock units granted to the Reporting Person on April 1, 2025. The number of shares withheld was determined based on the actual sale price of shares sold on April 7, 2026 pursuant to a sell-to-cover transaction.

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.

Reflects restricted stock units ("RSUs") that were issued to the reporting person on October 2, 2025 in connection with the acquisition of Iodine Software Holdings, Inc. by Waystar Holding Corp. These shares are subject to a lock-up agreement that restricts transfer for a period of six months following the closing of the acquisition.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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.

Includes unvested RSUs.

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).

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.

Includes unvested RSUs.

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).

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.

Includes unvested RSUs.

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).

These options are currently vested.

Includes unvested RSUs.

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).

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.

Includes unvested RSUs.

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).

These options are currently vested.

These options are currently vested.

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).

Includes unvested RSUs.