X0306 4 2020-12-23 0001581280 Twist Bioscience Corp TWST 0001753655 Leproust Emily M. C/O TWIST BIOSCIENCE CORPORATION 681 GATEWAY BLVD. SOUTH SAN FRANCISCO CA 94080 true true false false President & CEO Common Stock 2020-12-23 4 S false 4300 169.1388 D 429359 D Common Stock 2020-12-23 4 S false 700 170.3343 D 428659 D Common Stock 2020-12-24 4 M false 5300 5.95 A 433959 D Employee Stock Option (right to buy) 5.95 2020-12-24 4 M false 5300 0 D 2025-09-28 Common Stock 5300 95699 D The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan previously adopted by the Reporting Person on September 16, 2020. Represents the weighted average sales price per share. The shares sold at prices ranging from $169.00 to $169.49 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 $170.15 to $170.43 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. The option is immediately exercisable. 25% of the shares subject to the option vested on September 1, 2016 and 1/48th of the shares subject to the option vest on each monthly anniversary thereafter, subject to the Reporting Person's continuous service through each vesting date. /s/ William Solis, as Attorney-in-Fact for Emily M. Leproust 2020-12-28