Esther Rajavelu - 06 Feb 2026 Form 4 Insider Report for Spero Therapeutics, Inc. (SPRO)

Role: Chief Executive Officer, Chief Financial Officer and Chief Business Officer
Signature: /s/ Maegan Deare, Attorney-in-Fact for Esther Rajavelu
Issuer symbol: SPRO
Transactions as of: 06 Feb 2026
Net transactions value: -$207,484
Form type: 4
Filing time: 09 Feb 2026, 21:31:37 UTC
Previous filing: 04 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Rajavelu Esther	Chief Executive Officer, Chief Financial Officer and Chief Business Officer	C/O SPERO THERAPEUTICS, INC., 675 MASSACHUSETTS AVENUE, 14TH FLOOR, CAMBRIDGE	/s/ Maegan Deare, Attorney-in-Fact for Esther Rajavelu	09 Feb 2026	0001903716

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	SPRO	Common Stock	Sale	$87,558	-37,101	-3.4%	$2.36	1,062,907	06 Feb 2026	Direct	F1
transaction	SPRO	Common Stock	Sale	$119,926	-50,816	-4.8%	$2.36	1,012,091	06 Feb 2026	Direct	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Represents shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of RSUs. The sale occurred automatically to satisfy the tax withholding obligations to be funded by a "sell to cover" transaction and does not represent a discretionary trade by the Reporting Person.

Remarks:

Chief Executive Officer, Chief Financial Officer and Chief Business Officer