Additional Proxy Soliciting Materials (Form DEFA14A)

Step 1: Go to www.envisionreports.com/OABI. Step 2: Click on Cast Your Vote or Request Materials. Step 3: Follow the instructions on the screen to log in. www.envisionreports.com/OABI Online Go to www.envisionreports.com/OABI or scan the QR code - login details are located in the shaded bar below. Shareholder Meeting Notice 0495MC Important Notice Regarding the Availability of Proxy Materials for the OmniAb, Inc. Shareholder Meeting to be Held on Wednesday, June 17, 2026 Under Securities and Exchange Commission rules, you are receiving this notice that the proxy materials for the annual shareholders' meeting are available on the Internet. Follow the instructions below to view the materials and vote online or request a copy. The items to be voted on and location of the annual meeting are on the reverse side. Your vote is important! This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. We encourage you to access and review all of the important information contained in the proxy materials before voting. The 2025 Annual Report and Proxy Statement are available at: Obtaining a Copy of the Proxy Materials - If you want to receive a copy of the proxy materials, you must request one. There is no charge to you for requesting a copy. Please make your request as instructed on the reverse side on or before June 6, 2026 to facilitate timely delivery. 2 N O T Easy Online Access - View your proxy materials and vote. When you go online, you can also help the environment by consenting to receive electronic delivery of future materials. Step 4: Make your selections as instructed on each screen for your delivery preferences. Step 5: Vote your shares. Votes submitted electronically must be received by 11:59 PM, PT, on June 16, 2026.

Here's how to order a copy of the proxy materials and select delivery preferences: Current and future delivery requests can be submitted using the options below. If you request an email copy, you will receive an email with a link to the current meeting materials. PLEASE NOTE: You must use the number in the shaded bar on the reverse side when requesting a copy of the proxy materials. - Internet - Go to www.envisionreports.com/OABI. Click Cast Your Vote or Request Materials. - Phone - Call us free of charge at 1-866-641-4276. - Email - Send an email to [email protected] with "Proxy Materials OmniAb, Inc." in the subject line. Include your full name and address, plus the number located in the shaded bar on the reverse side, and state that you want a paper copy of the meeting materials. To facilitate timely delivery, all requests for a paper copy of proxy materials must be received by June 6, 2026. OmniAb, Inc.'s Annual Meeting of Shareholders will be held on Wednesday, June 17, 2026 at 5980 Horton Street, Suite 600, Emeryville, CA 94608, at 8:00 AM PT. Proposals to be voted on at the meeting are listed below along with the Board of Directors' recommendations. The Board of Directors recommends a vote FOR all the nominees listed and FOR Proposal 2: 1. Election of Directors: 01 - Matthew W. Foehr 02 - Jennifer Cochran, Ph.D. 2. Ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm PLEASE NOTE - YOU CANNOT VOTE BY RETURNING THIS NOTICE. To vote your shares you must go online or request a paper copy of the proxy materials to receive a proxy card. If you wish to attend and vote at the meeting, please bring this notice with you. Shareholder Meeting Notice