Release Details

SOUTH PLAINFIELD, NJ – February 10, 2014 – PTC Therapeutics, Inc. (NASDAQ: PTCT) announced today that it has commenced an underwritten public offering of approximately $75 million of shares of its common stock. The number of shares to be offered and the price for the proposed offering have not yet been determined. All of the shares in the offering are to be sold by PTC. PTC intends to grant the underwriters a 30-day option to purchase up to an additional 15 percent of the shares of common stock sold in the offering. The offering is subject to market and other conditions, and there can be no assurance as to whether or when the offering may be completed.

J.P. Morgan and Credit Suisse are acting as joint lead book-running managers for the offering.

A registration statement on Form S-1 relating to the securities proposed to be sold in this offering has been filed with the Securities and Exchange Commission but has not yet become effective. These securities may not be sold nor may offers to buy be accepted prior to the time that the registration statement becomes effective.

The offering will be made only by means of a prospectus. Copies of the preliminary prospectus relating to the offering may be obtained from J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717; telephone: 866-803-9204; or Credit Suisse Securities (USA) LLC, Attn: Prospectus Department, One Madison Avenue, New York, NY 10010; telephone: 800-221-1037; email: newyork.prospectus@credit-suisse.com.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of, these securities in any state or jurisdiction in which such offer, solicitation, or sale would be unlawful prior to the registration or qualification under the securities laws of such state or jurisdiction.

ABOUT PTC THERAPEUTICS, INC.

PTC is a biopharmaceutical company focused on the discovery and development of orally administered, proprietary small molecule drugs that target post-transcriptional control processes. Post-transcriptional control processes regulate the rate and timing of protein production and are essential to proper cellular function. PTC's internally discovered pipeline addresses multiple therapeutic areas, including rare disorders, oncology and infectious diseases. PTC has developed proprietary technologies that it applies in its drug discovery activities and which form the basis for collaborations with leading biopharmaceutical companies.

CONTACT Jane Baj PTC Therapeutics, Inc. 908-912-9167 jbaj@ptcbio.com