Spero Therapeutics Inc

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

(Amendment No. )

Filed by the Registrant [X]

Filed by a Party other than the Registrant [ ]

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Spero Therapeutics, Inc.

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

To Our Stockholders:

You are cordially invited to attend the 2024 annual meeting of stockholders of Spero Therapeutics, Inc. to be held at 9:00 a.m. Eastern Time on May 29, 2024. This year’s annual meeting will be conducted solely via live audio webcast on the Internet. You will be able to attend the annual meeting, vote and submit your questions during the annual meeting by visiting www.virtualshareholdermeeting.com/SPRO2024. You will not be able to attend the annual meeting in person.

Details regarding the meeting, the business to be conducted at the meeting, and information about Spero Therapeutics, Inc. that you should consider when you vote your shares are described in this proxy statement.

At the annual meeting, we will ask stockholders to (i) elect three people to our Board of Directors; (ii) ratify the selection of PricewaterhouseCoopers LLP as our independent registered public accounting firm for our fiscal year ending December 31, 2024; (iii) approve by an advisory vote the compensation of our named executive officers, as disclosed in this proxy statement; and (iv) approve an amendment to our 2017 Stock Incentive Plan, as amended, to increase the total number of shares of common stock authorized for issuance thereunder by 3,000,000 shares. The Board of Directors recommends the approval of each of the proposals. Such other business will be transacted as may properly come before the annual meeting.

Under U.S. Securities and Exchange Commission rules that allow companies to furnish proxy materials to stockholders over the Internet, we have elected to deliver our proxy materials to the majority of our stockholders over the Internet. This delivery process allows us to provide stockholders with the information they need, while at the same time conserving natural resources and lowering the cost of delivery. On April 16, 2024, we intend to begin sending to our stockholders a Notice of Internet Availability of Proxy Materials (the “Notice”) containing instructions on how to access our proxy statement for our 2024 annual meeting of stockholders and our 2023 annual report to stockholders. The Notice also provides instructions on how to vote online or by telephone, how to access the virtual annual meeting and how to receive a paper copy of the proxy materials by mail.

We hope you will be able to attend the annual meeting. Whether you plan to attend the annual meeting or not, it is important that you cast your vote either in person or by proxy. You may vote over the Internet as well as by telephone or by mail. When you have finished reading the proxy statement, you are urged to vote in accordance with the instructions set forth in this proxy statement. We encourage you to vote by proxy so that your shares will be represented and voted at the meeting, whether or not you can attend.

Thank you for your continued support of Spero Therapeutics, Inc.

President and Chief Executive Officer

NOTICE OF 2024 ANNUAL MEETING OF STOCKHOLDERS

TIME: 9:00 a.m. Eastern Time

DATE: May 29, 2024

ACCESS: www.virtualshareholdermeeting.com/SPRO2024

This year’s annual meeting will be a virtual meeting via live audio webcast on the Internet. You will be able to attend the annual meeting, vote and submit your questions during the meeting by visiting www.virtualshareholdermeeting.com/SPRO2024 and entering the 16-digit control number included in the Notice of Internet Availability of Proxy Materials or proxy card that you receive. For further information about the virtual annual meeting, please see the Questions and Answers about the Annual Meeting beginning on page 4.

PURPOSES:

WHO MAY VOTE:

You may vote if you were the record owner of Spero Therapeutics, Inc. common stock at the close of business on April 5, 2024.

Upon request, a list of stockholders of record will be available for examination by any stockholder at the annual meeting, and during the 10 days prior to the annual meeting at our principal executive offices located at 675 Massachusetts Avenue, 14th Floor, Cambridge, Massachusetts 02139.

All stockholders are cordially invited to attend the annual meeting. Whether you plan to attend the annual meeting or not, we urge you to vote and submit your proxy by the Internet, telephone or mail by following the instructions in the Notice of Internet Availability of Proxy Materials that you previously received and as described in this proxy statement in order to ensure the presence of a quorum. You may change or revoke your proxy at any time before it is voted at the meeting.

BY ORDER OF THE BOARD OF DIRECTORS

President and Chief Executive Officer