Cogent Sells $69 Million of Stock

Cogent Communications Group, Inc. (www.cogent.com) today announced that the underwriters of its public offering of 10,000,000 shares of common stock had exercised their option to purchase an additional 1,500,000 shares of stock. The stock was sold to the public at $6.00 per share on June 7, 2005.

The net proceeds will be used to repay $27 million of Cogent’s debt, fund the expansion of its sales and marketing efforts, to connect additional buildings to its network, primarily in Europe, and for general corporate purposes.

Cogent Communications (AMEX: COI) is a multinational, Tier 1 facilities-based ISP that specializes in providing businesses with high speed Internet access and point-to-point transport services.

Since Cogent’s inception, Cogent has exploited the benefits that IP technology provides, building a network that enables Cogent to offer large, dedicated bandwidth connections at highly competitive prices.

Information in this release may involve expectations, beliefs, plans, intentions or strategies regarding the future. These forward-looking statements involve risks and uncertainties.

All forward-looking statements included in this release are based upon information available to Cogent Communications Group, Inc. as of the date of the release, and we assume no obligation to update any such forward-looking statement.