X0306 4 2020-07-09 0 0001787400 Nkarta, Inc. NKTX 0001816523 Scheiner Zachary C/O RA CAPITAL MANAGEMENT 200 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 1 0 0 0 Stock Option (right to buy) 18.00 2020-07-09 4 A 0 10700 0.00 A 2030-07-08 Common Stock 10700 10700 I See Footnote All shares subject to the option vest 100% on the first anniversary of July 9, 2020, or, if earlier, on the day immediately preceding the first annual meeting of the Issuer's stockholders in 2021 at which one or more members of the Issuer's board of directors are to be elected. Each grant, to the extent outstanding and otherwise unvested, will become fully vest should a "change in control" of the Issuer occur (as described in the applicable award agreement) or upon the Reporting Person's separation from service with the Issuer due to the Reporting Person's death or "disability" (as described in the applicable award agreement). Under the Reporting Person's arrangement with RA Capital Management, L.P. (the "Adviser"), the Reporting Person holds the option for the benefit of the RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund") and a separately managed account (the "Account"). The Reporting Person is obligated to turn over to the Adviser any net cash or stock received from the option, which will offset advisory fees owed by the Fund, the Nexus Fund and the Account to the Adviser. The Reporting Person therefore disclaims beneficial ownership of the option and underlying common stock. /s/ Matthew Plunkett, Attorney-in-Fact for Zachary Scheiner 2020-07-10