Waystar Holding Corp. Secondary Offering by Derby LuxCo S.a r.l.

On September 12, 2025, Derby LuxCo S.a r.l., a significant owner of Waystar Holding Corp., sold 7,766,088 shares of common stock at $39.21 per share in a secondary offering. Following this transaction, Derby LuxCo still holds 24,879,437 shares of Waystar Holding Corp. common stock. The filing includes a disclaimer that the reporting persons are not admitting beneficial ownership of the securities for purposes of Section 16 of the Exchange Act, and they disclaim beneficial ownership except to the extent of their pecuniary interest. The filing was signed by representatives of Derby LuxCo S.a r.l. and EQT Fund Management S.a r.l. on September 16, 2025.