PTC THERAPEUTICS, INC.

Director and Officer Trading Arrangements

A portion of the compensation of our directors and officers (as defined in Rule 16a-1(f) under the Securities Exchange Act of 1934, as amended, or the Exchange Act) is in the form of equity awards and, from time to time, directors and officers engage in open-market transactions with respect to the securities acquired pursuant to such equity awards or other Company securities, including to satisfy tax withholding obligations when equity awards vest or are exercised, and for diversification or other personal reasons.

Transactions in Company securities by directors and officers are required to be made in accordance with our insider trading policy, which requires that the transactions be in accordance with applicable U.S. federal securities laws that prohibit trading while in possession of material nonpublic information. Rule 10b5-1 under the Exchange Act provides an affirmative defense that enables directors and officers to prearrange transactions in Company securities in a manner that avoids concerns about initiating transactions while in possession of material nonpublic information.

The following table describes, for the fourth quarter of 2025, each trading arrangement for the sale or purchase of Company securities adopted orterminated by our directors and officers that is either (1) a contract, instruction or written plan for the purchase or sale of the Company’s securities intended to satisfy the affirmative defense conditions of Rule 10b5-1(c), or a “Rule 10b5-1 trading arrangement”, or (2) a “non-Rule 10b5-1 trading arrangement” (as defined in Item 408(c) of Regulation S-K):

*This Rule 10b5-1 trading arrangement includes up to 353,311 shares of Company common stock available to be sold under Mr. Almstead’s previously executed trading arrangement, or the Prior Plan, which expires on March 31, 2026. Such shares are only available to be sold under this trading arrangement to the extent they remain unsold under the Prior Plan upon its expiration or termination.

(1) As previously disclosed, this trading arrangement related to 57,654 shares of Company common stock and had a scheduled expiration date of September 15, 2026, or such earlier date upon which all transactions were completed.