X0306 4 2017-10-26 0 0001629137 Global Blood Therapeutics, Inc. GBT 0001192591 HOMCY CHARLES J C/O GLOBAL BLOOD THERAPEUTICS, INC. 400 EAST JAMIE COURT, SUITE 101 SOUTH SAN FRANCISCO CA 94080 1 0 0 0 Common Stock 2017-10-26 4 S 0 54400 33.9298 D 83328 D Common Stock 2017-10-27 4 S 0 15600 34.0878 D 67728 D Common Stock 1600 I By Trust This transaction was executed in multiple trades at prices ranging from $33.75 to $34.15. The price reported above reflects the weighted average price. The Reporting person hereby undertakes to provide upon request to the SEC staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $33.90 to $34.45. The price reported above reflects the weighted average price. The Reporting person hereby undertakes to provide upon request to the SEC staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transaction was effected. /s/ Tricia Suvari, as Attorney-in-Fact 2017-10-27