Spero Therapeutics, Inc. — Director's Dealing 2017

Nov 1, 2017

SEC Form 3 — Initial Statement of Beneficial Ownership

Issuer: Spero Therapeutics, Inc. (SPRO)
CIK: 0001701108
Period of Report: 2017-11-01

Reporting Person: Deshpande Milind (Director)

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	16454	Direct

Holdings (Derivative)

Security	Exercise Price	Expiration	Underlying	Shares	Ownership
Stock Option (Right to Buy)	$5.90	2027-07-05	Common Stock (3290)		Direct
Stock Option (Right to Buy)	$5.90	2027-07-05	Common Stock (45191)		Direct

Footnotes

F1: The number of shares reported reflects a 1-for-6.0774 reverse stock split of the Issuer's common stock effected on October 20, 2017.

F2: The shares underlying this option vested as to 25% on August 24, 2016, with the remainder vesting in 36 equal monthly installments thereafter, subject to the Reporting Person's continued service through the applicable vesting date.

F3: The number of underlying shares of common stock and the exercise price reported reflect a 1-for-6.0774 reverse stock split of the Issuer's common stock effected on October 20, 2017.

F4: The shares underlying this option vest as to 25% on July 6, 2018, with the remainder vesting in 36 equal monthly installments thereafter, subject to the Reporting Person's continued service through the applicable vesting date.