WASHINGTON, D.C., June 14, 2005 - Cogent Communications Group, Inc. (Amex: COI) 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 stock was sold for $69 million. Cogent will receive net proceeds from the offering of approximately $65 million. The closing price of Cogent's common stock on June 14, 2005 was $7.04 per share.

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.

About Cogent Communications Group, Inc.

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. Cogent's facilities-based, all-optical IP network backbone spans over 11 countries and provides IP services in markets located in North America and Europe.

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. Network ownership also enables Cogent to offer superior customer support through the ability to control service delivery and network monitoring end-to-end.

Cogent Communications is headquartered at 1015 31st Street, NW, Washington, D.C. 20007.

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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. The statements in this release are not guarantees of future performance and actual results could differ materially from our current expectations. Numerous factors could cause or contribute to such differences. Some of the factors and risks associated with our business are discussed in Cogent's registration statements filed with the Securities and Exchange Commission and in its other reports filed from time to time with the SEC.

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