X0306 4 2019-10-23 0 0001581280 Twist Bioscience Corp TWST 0001755970 Finn Patrick John C/O TWIST BIOSCIENCE CORPORATION 455 MISSION BAY BOULEVARD SOUTH SAN FRANCISCO CA 94158 0 1 0 0 SVP, Commercial Operations Common Stock 2019-10-23 4 S 0 26664 23.0945 D 12338 D Common Stock 2019-10-23 4 S 0 100 23.68 D 12238 D Common Stock 2019-10-24 4 S 0 6236 22.4318 D 6002 D The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan previously adopted by the Reporting Person. Represents the aggregate of sales effected on the same day at different prices. Represents the weighted average sales price per share. The shares sold at prices ranging from $22.67 to $23.60 per share. Full information regarding the number of shares sold at each price shall be provided upon request to the staff of the U.S. Securities and Exchange Commission, the Issuer, or a security holder of the Issuer. Represents the weighted average sales price per share. The shares sold at prices ranging from $22.24 to $23.11 per share. Full information regarding the number of shares sold at each price shall be provided upon request to the staff of the U.S. Securities and Exchange Commission, the Issuer, or a security holder of the Issuer. /s/ William Solis, as Attorney-in-Fact for Patrick J. Finn 2019-10-25