X0306 4 2020-11-03 1 0001604477 SQZ Biotechnologies Co SQZ 0001830552 Amy Schulman, as Trustee The Armon R. Sharei Irrevocable GST Trust of 2016, U/D/T Dated December 29, 2016 200 ARSENAL YARDS BLVD, SUITE 210 WATERTOWN MA 02472 0 0 1 0 Common Stock 2020-11-03 4 C 0 11025 A 385891 D Series B Convertible Preferred Stock 2020-11-03 4 C 0 3453 D Common Stock 3637 0 D Series Seed Convertible Preferred Stock 2020-11-03 4 C 0 7016 D Common Stock 7388 0 D The preferred stock was convertible at any time, at the holder's election and had no expiration date. Each share of preferred stock automatically converted on a 1.053 for one basis into common stock upon the closing of the Issuer's initial public offering. The shares have no expiration date. /s/ Lawrence Knopf, Attorney-in-Fact for The Armon R. Sharei Irrevocable GST Trust of 2016 2020-11-03