Jean Francois Formela - 14 Sep 2021 Form 4 Insider Report for Translate Bio, Inc.

Footnote F1

As of September 14, 2021, Issuer was acquired in a cash tender by an indirect subsidiary of Sanofi, a French societe anonyme at a purchase price of $38.00 per share (the "Tender Offer"), as described more fully in the Schedule 14D-9 filed by the Issuer on August 16, 2021.

Footnote F2

1,872,115 of these shares are held directly by Atlas Venture Fund VIII, L.P. ("Atlas VIII''). 182,948 of these shares are held directly by Atlas Venture Associates VIII, L.P. ("AVA VIII LP"), the general partner of Atlas VIII. These shares were previously received by AVA VIII LP in a pro-rata stock distribution pursuant to a Rule 10b5-1 plan established by Atlas VIII. Atlas Venture Associates VIII, Inc. ("AVA VIII INC") is the sole general partner of AVA VIII LP. Dr. Formela is a director of AVA VIII INC and disclaims Section 16 beneficial ownership of the securities held by Atlas VIII and Atlas VIII LP, except to the extent of his pecuniary interest therein, if any. This report shall not be deemed to be an admission that Dr. Formela is the beneficial owner of such shares for the purposes of Section 16 or any other purpose.

Footnote F3

Under the terms of the Tender Offer, Issuer outstanding stock options, if not vested became vested, and all Issuer stock options were converted into cash consideration at the amount of the difference between the exercise price of the option and the Tender Offer price of $38.00 per share.

Footnote F4

This option was granted on June 18, 2019. The shares underlying this option became fully vested on the date of the Issuer's annual meeting of stockholders following the date of the grant, or June 16, 2020.

Footnote F5

This stock option was granted to the Reporting Person, a director of the Issuer. The proceeds of any sale of shares of common stock issued to the Reporting Person upon exercise of this stock option will be transferred to Atlas Venture Advisors, Inc. and as such, the Reporting Person disclaims ownership of such securities reported herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, except to the extent of his pecuniary interest therein, if any.

Footnote F6

This option was granted on June 16, 2020. The shares underlying this option became fully vested on the date of the Issuer's annual meeting of stockholders following the date of the grant, or June 16, 2021.

Footnote F7

This option was granted on June 16, 2021. This option will vest and become exercisable in full on the one year anniversary of the date of the award, or if earlier, the date of the Issuer's next annual meeting of stockholders following the date of the grant.

Footnote F8

This option was granted on March 7, 2018, with 25% of the shares underlying the option vesting on March 7, 2019 and thereafter 2.0833% vesting monthly until March 7, 2022.