GTT Communications, Inc. (“GTT” or the “Company”) (NYSE MKT: GTT) announced today an offering of 4,450,682 shares of common stock, of which 4,000,000 are being offered by the Company and 450,682 are being offered by the selling stockholders. The Company has also granted the underwriters an option to purchase up to 667,602 additional primary shares of common stock to cover over-allotments, if any. The Company will not receive any of the proceeds from the offering of shares by the selling stockholders, and will use the net proceeds from its offering of common stock for general corporate purposes. In connection with the offering William Blair & Company, L.L.C. will act as lead book-running manager. Craig-Hallum Capital Group LLC and Pacific Crest Securities LLC will act as joint book-running managers and Drexel Hamilton, LLC will act as Co-Manager. A shelf registration statement relating to the offering of the common stock has previously been filed with the U.S. Securities and Exchange Commission (“SEC”) and has become effective. The offering is being made only by means of a prospectus supplement and accompanying prospectus, forming a part of the effective registration statement. Before investing, you should read the prospectus supplement and the accompanying prospectus for information about GTT, the selling stockholders and this offering. A prospectus supplement relating to the offering will be filed with the SEC and will be available on the SEC's website at http://www.sec.gov. Alternatively, copies of the prospectus and prospectus supplement, when available, may be obtained by contacting William Blair & Company, L.L.C. at 222 West Adams Street, Chicago, IL 60606, Attention: Prospectus Department, by telephone at (800) 621-0687, or by email at email@example.com; by contacting Craig-Hallum Capital Group LLC at 222 South Ninth Street, Suite 350, Minneapolis, MN 55402, Attention: Prospectus Department or by phone at (612) 334-6300; or by contacting Pacific Crest Securities LLC at 111 South West Fifth Avenue, 42 nd Floor, Portland, OR 97204. This press release shall not constitute an offer to sell or the solicitation of an offer to buy any securities nor will there be any sale of these securities in any state or other 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 other jurisdiction.