X0306 4 2021-02-02 0 0001326110 NantKwest, Inc. NK 0001647994 Simon Barry J. C/O NANTKWEST, INC. 3530 JOHN HOPKINS COURT SAN DIEGO CA 92121 1 1 0 0 See remarks Common Stock 2021-02-02 4 M 0 82070 1.9984 A 3252610 D Common Stock 2021-02-02 4 S 0 82070 20.6507 D 3170540 D Stock Option (right to buy) 1.9984 2021-02-02 4 M 0 82070 0.00 D 2025-02-16 Common Stock 82070 132120 D The sale of shares reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan entered into by the reporting person on December 12, 2019. Represents the weighted average share price of an aggregate total of 82,070 shares sold in the price range of $20.50 to $20.98 by the reporting person. The reporting person undertakes to provide upon request by the Commission staff, the issuer or a security holder of the issuer, full information regarding the number of shares sold at each separate price. Subject to the reporting person's continuing service, one twenty-fourth (1/24th) of the shares subject to the option shall vest each month on the same day as the vesting commencement date, such that the shares subject to the option shall become fully vested and exercisable on the second (2nd) anniversary of the vesting commencement date. The vesting commencement date for this option is January 16, 2015. President and Chief Administrative Officer /s/ Sonja Nelson, as Attorney-in-Fact 2021-02-04