SCHEDULE: Advent International Discloses 5.8% Stake in Waystar

Advent International, L.P. and its affiliates reported a 5.8% beneficial ownership in Waystar Holding Corp. following the closing of Waystar's acquisition of Iodine Software Holdings, Inc.

Summary

• Advent International, L.P., Advent International GP, LLC, and AIO Holdings L.P. (collectively, the "Reporting Persons") beneficially own 11,059,899 shares of Waystar Holding Corp. Common Stock.
• This ownership represents approximately 5.8% of Waystar's outstanding Common Stock, calculated based on 174,146,070 shares outstanding as of September 11, 2025, plus 16,639,920 shares issued in connection with the merger.
• The shares were acquired as part of the consideration for Waystar Holding Corp.'s acquisition of Iodine Software Holdings, Inc. (Iodine), which closed on October 1, 2025.
• The merger consideration included approximately $458,598,270 in cash and 16,639,920 shares of Common Stock issued to certain equityholders of Iodine Software Parent, LLC.
• In connection with the merger, Advent International, L.P. and certain affiliates entered into a Stockholder and Lock-Up Agreement, restricting the transfer of their Common Stock for 18 months after the closing date.
• Advent International, L.P. also gained the right to nominate a director to Waystar's Board of Directors as long as they beneficially own at least 5% of the outstanding Common Stock.
• Waystar's Board of Directors was expanded from twelve to thirteen members, and Lauren Young was appointed as a director pursuant to Advent International, L.P.'s nomination right.
• Advent International, L.P. also entered into a Joinder Agreement to the Amended and Restated Registration Rights Agreement, providing for certain registration rights after the 18-month lock-up period.

Sentiment

Score: 7

Explanation: The filing indicates a significant strategic acquisition by Waystar, supported by Advent International's continued substantial ownership and board representation, suggesting confidence in the combined entity's future. The lock-up period provides stability for the new ownership structure.

Positives

• Advent International, L.P. maintains a significant 5.8% beneficial ownership in Waystar Holding Corp., indicating continued investment and confidence.
• Advent International, L.P. has secured a right to nominate a director to Waystar's Board, providing direct influence on corporate governance and strategic direction.
• The acquisition of Iodine Software Holdings, Inc. by Waystar Holding Corp. suggests strategic growth and expansion in the healthcare technology sector.
• Advent International, L.P. will have registration rights for its shares after an 18-month lock-up period, providing a clear path for potential future liquidity.

Negatives

• Advent International, L.P. and the Iodine CEO are subject to an 18-month lock-up period, restricting the transfer of their Common Stock received in the merger.

Risks

• The Reporting Persons intend to review their investment on an ongoing basis and may increase or decrease their position, which could lead to market volatility.
• Future transactions by the Reporting Persons will depend on various factors including the price and availability of Waystar's securities, general industry and economic conditions, and tax considerations.

Future Outlook

The Reporting Persons hold their securities for investment purposes and intend to review their investment on an ongoing basis. They may seek to increase or decrease their position in Waystar Holding Corp. through various transactions, including purchasing or selling shares or other financial instruments, depending on market conditions, Waystar's business prospects, and other factors. Registration rights for Advent International, L.P.'s shares will become active 18 months after the merger closing date.

Management Comments

• The Reporting Persons hold the reported securities for investment purposes, but intend to review their investment in the Issuer on an ongoing basis and may seek to increase or decrease their position.

Industry Context

This filing highlights a significant M&A activity in the healthcare technology sector, with Waystar Holding Corp. acquiring Iodine Software Holdings, Inc. The involvement of a major private equity firm like Advent International, L.P. as a substantial shareholder post-merger underscores continued investor interest and potential for growth in solutions for revenue cycle management and clinical artificial intelligence.

Management Changes

Corporate Governance

Related Party Transactions

• Waystar Holding Corp. entered into a Stockholder and Lock-Up Agreement with certain affiliates of Advent International, L.P. and other equityholders, restricting share transfers for 18 months.
• Waystar Holding Corp. entered into a Joinder Agreement to the Amended and Restated Registration Rights Agreement with Advent International, L.P., granting certain registration rights after the lock-up period.

Stakeholder Impact

• Shareholders: The issuance of 16,639,920 shares for the merger consideration results in dilution. The 18-month lock-up provides short-term stability, but potential future sales by Advent International, L.P. could impact share price.
• Employees: The acquisition of Iodine Software Holdings, Inc. means Iodine employees are now part of the combined Waystar entity, potentially leading to integration efforts and changes.
• Management: The addition of a new director nominated by Advent International, L.P. to the Board will introduce a new voice and perspective to strategic decision-making.

Next Steps

• Advent International, L.P. and its affiliates will continue to review their investment in Waystar Holding Corp. on an ongoing basis.
• Advent International, L.P. may engage in future transactions to increase or decrease its position in Waystar, including open market purchases or sales.
• The 18-month lock-up period for Advent International, L.P.'s shares will expire, after which their registration rights will become active.

Key Dates

Recommendation

The filing details the closing of Waystar's acquisition of Iodine Software and Advent International's resulting 5.8% beneficial ownership, along with a board seat. While the acquisition is a strategic move, and Advent's continued significant stake is a positive signal, the 18-month lock-up period and the stated intent of Advent to potentially adjust its position in the future suggest a 'hold' recommendation. Investors should monitor the integration of Iodine and the performance of the combined entity before making further investment decisions.

Keywords

Waystar Holding Corp., Advent International, Iodine Software, Schedule 13D, Merger, Beneficial Ownership, Healthcare Technology, Private Equity, Corporate Governance, Lock-Up Agreement