X0202 SCHEDULE 13G/A 0001274173-26-000072 0001274173 XXXXXXXX LIVE 1 Common Stock 03/31/2026 0001070081 PTC THERAPEUTICS, INC. 69366J200 500 WARREN CORPORATE CENTER DRIVE WARREN NJ 07059 Rule 13d-1(b) JANUS HENDERSON GROUP PLC Y9 0 7193433 0 7193433 7193433 8.7 HC PTC THERAPEUTICS, INC. 500 WARREN CORPORATE CENTER DRIVE WARREN, NJ 07059 Janus Henderson Group plc 201 Bishopsgate EC2M 3AE, United Kingdom Y9 N HC Janus Henderson Group plc (JHG) is the ultimate parent of a number of SEC-registered investment advisers and foreign equivalents thereof, including but not limited to Janus Henderson Investors US LLC, Janus Henderson Investors UK Limited, Janus Henderson Investors Australia Institutional Funds Management Limited, Janus Henderson Investors Middle East Limited, Janus Henderson Investors (Jersey) Limited, Janus Henderson Investors (Japan) Limited, Janus Henderson Investors (Singapore) Limited, Kapstream Capital Pty Limited, Privacore Capital Advisors LLC, Tabula Investment Management Limited, and Victory Park Capital Advisors LLC (each, an Asset Manager and together, the Asset Managers). The Asset Managers generally exercise investment and/or voting discretion on behalf of their clients which include investment companies, other investment advisers, institutional separate accounts and retail separate accounts (collectively referred to herein as Managed Portfolios). As a result of their exercise of investment and/or voting discretion on behalf of the Managed Portfolios, the Asset Managers may be deemed to be the beneficial owner of 7,193,433 common stock of PTC Therapeutics, Inc. However, the Asset Managers do not have the right to receive any dividends from, or the proceeds from the sale of, the securities held in the Managed Portfolios and disclaim any ownership associated with such rights. 8.7 0 7193433 0 7193433 Y N N The Managed Portfolios have the right to receive all dividends from, and the proceeds from the sale of, the securities held in their respective accounts. Of the Managed Portfolios, none own more than five percent of the common stock of PTC Therapeutics, Inc. N Please refer to Exhibit 99. N N/A N N/A 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 24: Power of Attorney Exhibit 99: Item 7 JANUS HENDERSON GROUP PLC Kristin Mariani 5/15/2026