X0306 4 2019-05-18 0 0001351288 GW PHARMACEUTICALS PLC GWPH 0001754122 Knappertz Volker SOVEREIGN HOUSE, VISION PARK, HISTON CAMBRIDGE X0 CB24 9BZ UNITED KINGDOM 0 1 0 0 Chief Medical Officer Ordinary Shares 2019-05-18 4 M 0 12144 0.0013 A 97968 D Ordinary Shares 2019-05-20 4 S 0 5832 14.52 D 92136 D Ordinary Shares 2019-05-20 4 S 0 6312 14.76 D 85824 D Restricted Stock Units 0.0013 2019-05-18 4 M 0 12144 0.00 D 2019-05-18 2019-05-18 Ordinary Shares 12144 0 D Vesting of restricted stock units previously reported as stock options on the reporting person's Form 3 filed on October 1, 2018. These ordinary shares are subsequently converted into American Depositary Shares ("ADS") of the Issuer. Converted from British Pounds Sterling to U.S. Dollars using currency ratio of 1.00 British Pound Sterling = 1.27 U.S. Dollars as of May 17, 2019. Includes 49,632 and 27,456 ordinary shares underlying restricted stock units previously reported as stock options on the reporting person's Form 3 filed on October 1, 2018 and Form 4 filed on March 5, 2019, respectively. Represented by ADSs. The price reported in Column 4 is price per ordinary share converted from price per ADS. The price reported in Column 4 is a weighted average price per ordinary share ($177.13 per ADS). These shares were sold in multiple transactions at prices ranging from $177.06 per ADS (or $14.76 per ordinary share) to $177.13 per ADS (or $14.76 per ordinary share), inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range. The reporting person's Form 3 filed on October 1, 2018 contained stock options to purchase 12,144 ordinary shares vesting on May 18, 2019 and expiring on March 15, 2020. These securities are restricted stock units with a nominal exercise price and vest automatically upon vesting date. /s/ Volker Knappertz 2019-05-21