Cogent Sells US$93 Million of Common Stock

Cogent Communications Group, Inc. (http://www.cogentco.com) announced that the underwriters of the public offering of 9,000,000 shares of its common stock had exercised their option to purchase an additional 1,350,000 shares of stock from Cogent, Dave Schaeffer, Cogent's Chairman and CEO, and certain selling stockholders. A total of 10,350,000 shares of common stock were sold by Cogent and the selling stockholders at a price of US$9.00 per share, resulting in gross proceeds, before underwriting discounts and offering expenses, of approximately US$93 million.

The sale of 4.35 million shares by Cogent resulted in gross proceeds to Cogent, before underwriting discounts and offering expenses, of approximately US$39.15 million. The offering was completed on June 7, 2006. The closing price of Cogent's common stock on June 7, 2006 was US$9.26 per share. Lehman Brothers and Bear, Stearns & Co. Inc. acted as joint book-running managers of the offering, Thomas Weisel Partners LLC acted as joint lead manager and Wachovia Securities and Friedman Billings Ramsey acted as co-managers.

This press release shall not constitute an offer to sell or a solicitation of an offer to buy common stock nor shall there be any sale of such 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

Copies of the final prospectus supplement and related base prospectus for the offering may be obtained by contacting Lehman Brothers Inc., c/o ADP Financial Services Prospectus Fulfillment, 1155 Long Island Avenue, Edgewood, NY 11717, Fax: +1-(631)-254-7268 Email: monica_castillo@adp.com, or Bear, Stearns & Co. Inc., c/o Prospectus Department, 383 Madison Avenue, New York, NY 10179 Phone: +1-(866)-803-9204

About Cogent Communications

Cogent Communications (Nasdaq: CCOI) is a multinational, Tier 1 facilities-based ISP headquartered at 1015 31st Street, NW, Washington, D.C. 20007. Cogent specializes in providing businesses with high speed Internet access and point-to-point transport services. Cogent's facilities-based, all-optical IP network backbone spans 14 countries and provides IP services in over 95 markets located in North America and Europe.

Cogent Communications can be reached in the United States at +1-(202) -295-4200 or via email at info@cogentco.com.