X0306 4 2021-04-19 0 0001070081 PTC THERAPEUTICS, INC. PTCT 0001808968 Klein Matthew B. C/O PTC THERAPEUTICS, INC. 100 CORPORATE COURT SOUTH PLAINFIELD NJ 07080 0 1 0 0 Chief Development Officer Common Stock 2021-04-19 4 S 0 859 48.168 D 18450 D Common Stock 2021-04-20 4 S 0 1444 46.582 D 17006 D Common Stock 2021-04-20 4 S 0 197 47.919 D 16809 D Represents shares automatically sold pursuant to an irrevocable sell to cover election to satisfy tax withholding obligations in connection with the vesting of 2,500 RSUs from a April 16, 2020 grant of 10,000 RSUs. This transaction was effected pursuant to a written Rule 10b5-1 plan adopted by the Reporting Person on March 10, 2021. This price represents the weighted average price of sale transactions that were executed in multiple trades at prices ranging from $46.24 to $47.06 per share. The Reporting Person hereby undertakes, upon request by the SEC staff, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price. This price represents the weighted average price of sale transactions that were executed in multiple trades at prices ranging from $47.68 to $48.17 per share. The Reporting Person hereby undertakes, upon request by the SEC staff, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price. /s/ Avraham S. Adler, attorney-in-fact 2021-04-21