SCHEDULE 13G/A 0001663900 XXXXXXXX LIVE 1 Common Stock, $0.001 par value per share 09/30/2025 0001842718 Integral Ad Science Holding Corp. 45828L108 12 East 49th Street, 20th Floor New York NY 10017 Rule 13d-1(b) SUNRIVER MANAGEMENT LLC b DE 0.00 7120157.00 0.00 7120157.00 7120157.00 N 4.3 IA OO RANDOLPH WILLETT COOK b X1 0.00 7120157.00 0.00 7120157.00 7120157.00 N 4.3 HC IN Integral Ad Science Holding Corp. 12 East 49th Street, 20th Floor, New York, NY 10017 Sunriver Management LLC Randolph Willett Cook Sunriver Management LLC 2 Sound View Drive, 2nd Floor Greenwich, CT 06830 Randolph Willett Cook 2 Sound View Drive, 2nd Floor Greenwich, CT 06830 Sunriver Management LLC - Delaware Randolph Willett Cook - United States N IA HC Sunriver Management LLC - 7,120,157 Randolph Willett Cook - 7,120,157 Sunriver Management LLC - 4.3% Randolph Willett Cook - 4.3% Sunriver Management LLC - 0 Randolph Willett Cook - 0 Sunriver Management LLC - 7,120,157 Randolph Willett Cook - 7,120,157 Sunriver Management LLC - 0 Randolph Willett Cook - 0 Sunriver Management LLC - 7,120,157 Randolph Willett Cook - 7,120,157 N Y N All of the securities reported in this Schedule 13G are directly owned by advisory clients of Sunriver Management LLC. None of those advisory clients may be deemed to beneficially own more than 5% of the Common Stock, $0.001 par value. N Please see Exhibit B attached hereto. Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. [Exhibit A - Joint Filing Agreement] [Exhibit B - Control Person Identification] SUNRIVER MANAGEMENT LLC By: /s/ Randolph Willett Cook 11/13/2025 RANDOLPH WILLETT COOK By: /s/ Randolph Willett Cook 11/13/2025 * Each Reporting Person disclaims beneficial ownership of the reported securities except to the extent of his, her or its pecuniary interest therein, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose. To the extent that "ownership of 5 percent or less of a class" was indicated in Item 5, such response only applies to the Reporting Person(s) that indicated elsewhere herein that it beneficially owns five percent (5%) or less of the class.