X0206 3 2022-04-28 0 0001888012 HilleVax, Inc. HLVX 0001790879 Frazier Life Sciences X, L.P. 601 UNION STREET, SUITE 3200 SEATTLE WA 98101 0 0 1 0 0001790880 FHMLS X, L.P. 601 UNION STREET, SUITE 3200 SEATTLE WA 98101 0 0 1 0 0001790811 FHMLS X, L.L.C. 601 UNION STREET, SUITE 3200 SEATTLE WA 98101 0 0 1 0 0001341382 Topper James N 601 UNION STREET, SUITE 3200 SEATTLE WA 98101 0 0 1 0 0001365617 Heron Patrick J 601 UNION STREET, SUITE 3200 SEATTLE WA 98101 1 0 1 0 Common Stock 4034397 D Convertible Promissory Notes 13.60 Common Stock 2736234 D The shares are held directly by Frazer Life Sciences X, L.P. ("FLS X"). The general partner of FLS X is FHMLS X, L.P., and the general partner of FHMLS X, L.P. is FHMLS X, L.L.C. James Topper, M.D., Ph.D., and Patrick Heron are the sole managing members of FHMLS X, L.L.C. and share voting and investment power of the securities held by FLS X. Dr. Topper and Mr. Heron disclaim beneficial ownership of such securities except to the extent of their pecuniary interest therein. The outstanding principal and unpaid accrued interest due on the Convertible Promissory Notes will automatically convert into shares of the Issuer's Common Stock immediately prior to the closing of the initial public offering. Frazier Life Sciences X, L.P., By: FHMLS X, L.P., its general partner, By: FHMLS X, L.L.C., its general partner, By: /s/ James N. Topper, Managing Director 2022-04-28 FHMLS X, L.P., By: FHMLS X, L.L.C., its general partner, By: /s/ James N. Topper, Managing Director 2022-04-28 FHMLS X, L.L.C., By: /s/ James N. Topper, Managing Director 2022-04-28 /s/ James N. Topper 2022-04-28 /s/ Patrick J. Heron 2022-04-28