Additional Proxy Soliciting Materials (Form DEFA14A)

Your Vote Counts! Smartphone users Point your camera here and vote without entering a control number For complete information and to vote, visit www.ProxyVote.com Control # V93017-P48220 *Please check the meeting materials for any special requirements for meeting attendance. PUBMATIC, INC. 601 MARSHALL ST. REDWOOD CITY, CA 94063 PUBMATIC, INC. 2026 Annual Meeting Vote by May 28, 2026 11:59 PM ET You invested in PUBMATIC, INC. and it's time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy materials for the stockholder meeting to be held on May 29, 2026. Get informed before you vote View the Notice, Proxy Statement and Annual Report on Form 10-K online OR you can receive a free paper or email copy of the material(s) by requesting prior to May 15, 2026. If you would like to request a copy of the material(s) for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to [email protected]. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy. Vote Virtually at the Meeting* May 29, 2026 9:00 a.m. Pacific Time Virtually at: www.virtualshareholdermeeting.com/PUBM2026

Vote at www.ProxyVote.com THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming stockholder meeting. Please follow the instructions on the reverse side to vote these important matters. 1. Election of Directors For Nominees: Susan Daimler 04) Rajeev K. Goel 07) Nick Mehta Shelagh Glaser 05) Anton Hanebrink 08) Jacob Shulman Amar K. Goel 06) Ramon Jones 2. The ratification of the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026. For 3. To approve, on a non-binding advisory basis, the compensation of our named executive officers. For NOTE: Such other business as may properly come before the meeting or any adjournment thereof. Voting Items Board Recommends V93018-P48220 Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click "Delivery Settings".