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PTC Therapeutics, Inc.

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Your Vote Counts! Smartphone users Point your camera here and vote without entering a control number V1.1 For complete information and to vote, visit www.ProxyVote.com Control # V14029-P92483 PTC THERAPEUTICS, INC. 100 CORPORATE COURT SOUTH PLAINFIELD, NJ 07080-2449 PTC THERAPEUTICS, INC. 2023 Annual Meeting June 6, 2023 9:00 AM ET Virtual Meeting Site: www.virtualshareholdermeeting.com/PTCT2023 Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting to Be Held on June 6, 2023 You invested in PTC THERAPEUTICS, INC. and it’s time to vote! You have the right to vote on proposals being presented at the 2023 Annual Meeting. Vote Virtually at the 2023 Annual Meeting* Vote on June 6, 2023 9:00 AM ET Visit www.virtualshareholdermeeting.com/PTCT2023 *Please check the proxy and www.virtualshareholdermeeting.com/PTCT2023 for any special requirements for meeting attendance. Get informed before you vote View the Notice and Proxy Statement and 2022 Annual Report online OR you can receive a free paper or email copy of the material(s) by requesting prior to May 23, 2023. 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 sendmaterial@proxyvote.com. 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 in Advance of the 2023 Annual Meeting Vote by June 5, 2023 11:59 PM ET. For shares held in a Plan, vote by June 3, 2023 11:59 PM ET. Visit www.ProxyVote.com

Vote at www.ProxyVote.com Voting Items Board Recommends V14030-P92483 THIS IS NOT A VOTABLE BALLOT This is 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. Please follow the instructions on the reverse side to vote these important matters. Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Delivery Settings”. 2. Ratification of the appointment of Ernst & Young LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2023. 3. Approval on a non-binding, advisory basis, of the Company’s named executive officer compensation as described in the proxy statement. NOTE: To transact any other business that may be properly brought before the meeting or any adjournment or postponement of the meeting. For For For 1. Election of Four Class I Directors Nominees: 01) William F. Bell, Jr. 02) Matthew B. Klein, M.D., M.S., F.A.C.S. 03) Stephanie S. Okey, M.S. 04) Jerome B. Zeldis, M.D., Ph.D.