Spero Therapeutics, Inc. — Director's Dealing 2017

Nov 7, 2017

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Spero Therapeutics, Inc. (SPRO)
CIK: 0001701108
Period of Report: 2017-11-06

Reporting Person: Breum Casper (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2017-11-06	Common Stock	C	289102	—	Acquired	289102	Indirect
2017-11-06	Common Stock	C	179450	—	Acquired	468552	Indirect
2017-11-06	Common Stock	C	408937	—	Acquired	877489	Indirect
2017-11-06	Common Stock	P	214285	$14.00	Acquired	1091774	Indirect

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2017-11-06	Series A Preferred Stock	$	C	1153846	Disposed		Common Stock (289102)	Indirect
2017-11-06	Series B Preferred Stock	$	C	681818	Disposed		Common Stock (179450)	Indirect
2017-11-06	Series C Preferred Stock	$	C	2485272	Disposed		Common Stock (408937)	Indirect

Footnotes

F1: Reflects shares of the Issuer's common stock that were purchased in connection with the Issuer's initial public offering.

F2: Amount of underlying securities reflects the application of the applicable conversion ratio as set forth in the Issuer's Amended and Restated Certificate of Incorporation in effect immediately prior to the closing of the initial public offering (as adjusted by the 1-for-6.0774 reverse stock split of the Issuer's common stock effected on October 20, 2017). The preferred stock had no expiration date.

F3: Shares held by Lundbeckfond Invest A/S. The Reporting Person shares voting and investment power with respect to the shares held by Lundbeckfond Invest A/S and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.