SEC Form 4 · accession 0000903423-17-000632

Spero Therapeutics, Inc. · SPRO

Statement of changes in beneficial ownership, as filed. Original on EDGAR ↗

Reporting owner

10% Owner

Period of report

Nov 6, 2017

Accepted (ET)

Nov 7, 2017 · 7:42 pm EST

Rule 10b5-1 plan

unknown — predates the checkbox

Issuer CIK

0001701108

Table I — non-derivative securities

Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F2,F3	Nov 6, 2017	C	244,147	—	A	244,147	I	See Footnote
Common Stock^F2,F3	Nov 6, 2017	C	246,272	—	A	490,419	I	See Footnote
Common Stock^F2,F3	Nov 6, 2017	C	328,992	—	A	819,411	I	See Footnote
Common Stock^F2,F3	Nov 6, 2017	C	606,024	—	A	1,425,435	I	See Footnote
Common Stock^F1,F3	Nov 6, 2017	P	428,571	$14.00	A	1,854,006	I	See Footnote

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Junior preferred stock^F3,F2	—	Nov 6, 2017	C	1,483,784	D	—	—	Common Stock	244,147	I
Series A preferred stock^F3,F2	—	Nov 6, 2017	C	982,906	D	—	—	Common Stock	246,272	I
Series B preferred stock^F3,F2	—	Nov 6, 2017	C	1,250,000	D	—	—	Common Stock	328,992	I
Series C preferred stock^F3,F2	—	Nov 6, 2017	C	3,683,045	D	—	—	Common Stock	606,024	I

F1S.R. One, Limited acquired 428,571 common shares of the Issuer in connection with the Issuer's initial public offering.
F2Amount 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.
F3The shares reported herein are held of record by S.R. One, Limited, an indirect,wholly-owned subsidiary of GlaxoSmithKline plc (the "Reporting Person").