Spero Therapeutics Announces Pricing of Initial Public Offering

Spero Therapeutics, Inc., a multi-asset, clinical-stage biopharmaceutical company focused on identifying, developing and commercializing novel treatments for multi-drug resistant bacterial infections, today announced the pricing of its initial public offering of 5,500,000 shares of its common stock at a public offering price of $14.00 per share, before underwriting discounts and commissions. Spero Therapeutics, Inc.’s shares are expected to begin trading on The Nasdaq Global Select Market on November 2, 2017 under the symbol “SPRO.”  All of the shares are being offered by Spero Therapeutics, Inc.  In addition, Spero Therapeutics, Inc. has granted the underwriters a 30-day option to purchase up to 825,000 additional common shares at the initial public offering price.  The offering is expected to close on November 6, 2017, subject to the satisfaction of customary closing conditions.

BofA Merrill Lynch, Cowen and Stifel are serving as joint book-running managers for the proposed offering. Oppenheimer & Co. is acting as a co-manager for the proposed offering.

A registration statement relating to these securities has been filed with, and declared effective by, the Securities and Exchange Commission.  The offering will be made only by means of a prospectus. Copies of the final prospectus relating to this offering, when available, may be obtained from BofA Merrill Lynch, NC1-004-03-43, 200 North College Street, 3rd floor, Charlotte, NC 28255-0001, Attention: Prospectus Department, or by email at [e-mail]; from Cowen and Company, LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, Attention: Prospectus Department, or by telephone at [phone]; and from Stifel, Nicolaus & Company, Incorporated, Attention: Syndicate, One Montgomery Street, Suite 3700, San Francisco, CA 94104, or by telephone at [phone] or by email at [e-mail].

This press release shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Spero

Spero Therapeutics is a multi-asset, clinical-stage biopharmaceutical company focused on identifying, developing and commercializing novel treatments for multi-drug resistant bacterial infections.

Spero Media and Investor Contact

Sharon KlahreDirector, Investor [e-mail]