Spero Therapeutics, Inc. — Director's Dealing 2021

Sep 1, 2021

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Spero Therapeutics, Inc. (SPRO)
CIK: 0001701108
Period of Report: 2021-08-30

Reporting Person: Aquilo Capital Management, LLC (10% Owner)
Reporting Person: Aquilo Capital, L.P. (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2021-08-30	Common Stock, $0.001 par value	P	44042	$17.8661	Acquired	4309385	Indirect
2021-08-31	Common Stock, $0.001 par value	P	48645	$18.9261	Acquired	4358030	Indirect

Footnotes

F1: The reporting persons are Aquilo Capital, L.P. (the "Fund"), Aquilo Capital Management, LLC ("Aquilo") and Marc R. Schneidman. Aquilo is the general partner and investment adviser of the Fund and other funds managed by Aquilo that hold securities directly for the benefit of their investors. Aquilo may be deemed to beneficially own such securities indirectly as the investment adviser and general partner of the Fund and affiliated funds, and Mr. Schneidman may be deemed to beneficially own them indirectly as the control person of Aquilo. Each of, Aquilo, the Fund and Mr. Schneidman disclaims beneficial ownership of such securities except to the extent of his or its pecuniary interest therein.

F2: Aquilo Capital, LP owns only 3,378,881 of the 4,309,385 shares deemed to be beneficially owned by Aquilo Capital Management, LLC. Aquilo Capital, LP did not purchase any of the 44,042 shares purchased in this transaction on 08/30/2021.

F3: Aquilo Capital, LP owns only 3,378,881 of the 4,358,030 shares deemed to be beneficially owned by Aquilo Capital Management, LLC. Aquilo Capital, LP did not purchase any of the 48,645 shares purchased in this transaction on 08/31/2021.