SOUTH PLAINFIELD, NJ - November 10, 2005 - PTC Therapeutics, Inc. (PTC), a privately held biopharmaceutical company focused on the discovery, development, and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms, today announced the closing of a $26.6 million equity financing. The round was led by current investors, Credit Suisse First Boston Private Equity and HBM BioVentures, with a strong syndicate of new and existing investors, including: Vulcan Ventures, Novo A/S, Delphi Ventures, Bay City Capital, Novartis BioVentures, Amgen Ventures, and HealthCap."The proceeds of this round of financing will be applied towards the clinical development of PTC124, the advancement of our preclinical oncology and antiviral programs, and our drug discovery programs in multiple therapeutic areas," stated Stuart Peltz, Ph.D., President and CEO of PTC Therapeutics. "The continued support from our investors reflects our track-record of consistently meeting our scientific and corporate milestones." "The founders of PTC were pathfinders in anticipating the significance of targeting RNA biology for the development of pharmaceutical products," commented Michael Schmertzler of Credit Suisse First Boston Private Equity. "Since our early investment in PTC, the management team has done an excellent job building on the founders' original insights. We are impressed by the portfolio of compounds that PTC is developing and the range of critical diseases that they may address. We look forward to the results of PTC's first clinical trials in Duchenne muscular dystrophy and cystic fibrosis." "We are proud to co-lead this additional round of financing which strengthens PTC's financial position in preparation for critical milestones expected in 2006," added Axel Bolte, of HBM Bioventures. "PTC continues to excel in translating its proprietary approach to drug discovery into programs targeting diseases with large unmet medical needs." ABOUT PTC THERAPEUTICS, INC. PTC is a biopharmaceutical company focused on the discovery, development, and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms. Post-transcriptional control processes are the sequence of events in the cell that ultimately regulate the rate and timing of all protein production. PTC's compounds alter these processes by selectively modulating how RNA is used to produce proteins. By applying this approach, PTC has advanced its drug discovery programs rapidly from targets to preclinical and clinical drug candidates, building a robust pipeline across genetic disorders, oncology, and infectious diseases.