SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 -------------------- FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 -------------------- Date of report (date of earliest event reported): February 4, 2002 ---------------- Cogent Communications Group, Inc. --------------------------------- (Exact Name of Registrant as Specified in Charter) 1-31227 ------- (Commission File No.) 52-2337274 ---------- (IRS Employer Identification No.) Delaware -------- (State or Other Jurisdiction of Incorporation) 1015 31st Street N.W. Washington, DC 20007 (Address of Principal Executive Offices) (202) 295-4200 -------------- (Registrant's telephone number, including area code)

ITEM 2. ACQUISITION OR DISPOSITION OF ASSETS. In a press release dated February 4, 2002, Cogent Communications Corporation, Inc. ("Cogent") announced that it had consummated its merger with Allied Riser Communications Corporation ("Allied Riser"). The press release is attached hereto as Exhibit 99.1. As described in the press release, Cogent acquired Allied Riser by merging a wholly owned subsidiary of Cogent with and into Allied Riser. As a consequence of the merger, Allied Riser became a wholly owned subsidiary of Cogent. In the merger, stockholders of Allied Riser received approximately 0.0321679 shares of Cogent's common stock for each share of Allied Riser common stock that they owned. As a result of the merger, Allied Riser stockholders own approximately 13.36% of Cogent's outstanding common stock on a fully diluted basis, subject to certain adjustments. The consideration paid by Cogent was determined pursuant to negotiations between Cogent and Allied Riser. The merger is more fully described in the Form S-4 filed by the Company on October 16, 2001, as amended. One former officer of Allied Riser is expected to become a director of, and consultant to, Cogent as a result of the merger. ITEM 7. FINANCIAL STATEMENTS AND EXHIBITS (a) Financial Statements of Businesses Acquired. Pursuant to Item 7(a)(4) of Form 8-K, the financial statements required by Item 7(a) will be filed on or prior to April 20, 2002. (b) Pro Forma Financial Information. Pursuant to Items 7(a)(4) and 7(b)(2) of Form 8-K, the financial statements required by Item 7(b) will be filed on or prior to April 20, 2002. (c) Exhibits 2.1 Agreement and Plan of Merger, dated as of August 28, 2001, by and among Cogent, Allied Riser and the merger subsidiary (previously filed as Appendix A to our Registration Statement on Form S-4, Commission File No. 333-71684, filed October 16, 2001, and incorporated herein by reference). 2.2 Amendment No. 1 to the Agreement and Plan of Merger, dated as of October 13, 2001, by and among Cogent, Allied Riser and the merger subsidiary (previously filed as Appendix B to our Registration Statement on Form S-4, Commission File No. 333-71684, filed October 16, 2001, and incorporated herein by reference). 99.1 Press Release announcing the consummation of the merger of Cogent and Allied Riser dated January 31, 2002 (attached hereto). <Page> Exhibit Index <TABLE> <CAPTION> EXHIBIT NO. DESCRIPTION <S> <C> 2.1 Agreement and Plan of Merger, dated as of August 28, 2001, by and among Cogent, Allied Riser and the merger subsidiary (previously filed as Appendix A to our Registration Statement on Form S-4, Commission File No. 333-71684, filed October 16, 2001, and incorporated herein by reference) 2.2 Amendment No. 1 to the Agreement and Plan of Merger, dated as of October 13, 2001, by and among Cogent, Allied Riser and the merger subsidiary (previously filed as Appendix B to our Registration Statement on Form S-4, Commission File No. 333-71684, filed October 16, 2001, and incorporated herein by reference) 99.1 Press Release announcing the consummation of the merger of Cogent and Allied Riser dated January 31, 2002 (attached hereto). </TABLE>

SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. COGENT COMMUNICATIONS GROUP, INC. Date: February 4, 2002 By: -------------------------------- Name: David Schaeffer Title: Chief Executive Officer

Exhibit 99.1 [COGENT COMMUNINCATIONS LOGO] FOR IMMEDIATE RELEASE Cogent Public Relations Contact: Jeff Henriksen Kristin Duskin-Gadd (202) 295-4388 (828) 684-2434 jhenriksen@cogentco.com kduskin-gadd@interprosepr.com ----------------------- ----------------------------- Cogent Investor Relations Contact: Helen Lee, CFO 202-295-4264 hlee@cogentco.com ----------------- COGENT COMMUNICATION'S ACQUISITION OF ALLIED RISER COMPLETED COGENT TO BEGIN TRADING ON AMEX TOMORROW, TUESDAY FEBRUARY 5, 2002 WASHINGTON, D.C. - February 4, 2002 - Cogent Communications Group, Inc., a Tier One, next-generation optical ISP announced today that it closed its merger transaction with Allied Riser Communications Corporation (NASDAQ: ARCC) and Cogent will begin trading on the American Stock Exchange tomorrow morning, February 5, 2002. As a result of the transaction, Allied Riser became a wholly owned subsidiary of Cogent. On January 31st, Allied Riser shareholders approved the merger of the two companies at a shareholder meeting held in Dallas, Texas. Pursuant to the terms of the merger agreement, Allied Riser shareholders will receive approximately .032 shares of common stock of Cogent for each Allied Riser share held, in a transaction structured to be a tax-free exchange. Upon completion of the merger, Allied Riser became a wholly owned subsidiary of Cogent and Allied Riser's common stock will be voluntarily removed from listing on the NASDAQ Stock Market's National Market System. Cogent's common stock was immediately listed and will commence trading tomorrow morning on the American Stock Exchange under the symbol COI. Jerry Dinsmore, departing Chairman, Chief Executive Officer and President of Allied Riser stated "this transaction provides the opportunity for all stakeholders in Allied Riser to participate in the further development of a unique network combining ARC's in-building fiber optic facilities with Cogent's expanding national network." -more-

Cogent/ARCC Merger/Page Two Upon completion of the merger, Dave Schaeffer, Chairman and Chief Executive Officer of Cogent, said, "Our successful acquisition of Allied Riser provides Cogent with necessary in-building networks as well as valued building access rights already negotiated with hundreds of building owners and real estate investment trusts across the country. This will enable Cogent to dramatically accelerate its business plan and increase its footprint in the 20 markets we currently serve. Cogent is now uniquely positioned to provide LAN speed (100 Mbps) access to the Internet to a significantly larger universe of tenants at costs equivalent to what they currently pay for a traditional T1 connection at 1.5 Mbps." ABOUT COGENT COMMUNICATIONS Cogent Communications (AMEX: COI) is a next generation optical ISP focused on delivering ultra-high speed Internet access and transport services to businesses in the multi-tenant marketplace and to service providers located in major metropolitan areas across the United States. Cogent's signature service offered to commercial end-users of 100 Mbps for $1,000 per month, offers 100 times the observed bandwidth of a T-1 connection at up to two-thirds of the cost. The Cogent solution makes ultra-high speed Internet access an affordable reality for small and medium-sized businesses, as well as large enterprises and service providers. Cogent's facilities-based, all-optical end-to-end IP network enables non-oversubscribed 100 Mbps and 1000 Mbps connectivity for radically low, unmetered pricing levels. Cogent's network consists of a dedicated nationwide multiple OC-192 fiber backbone, multiple intra-city OC-48 fiber rings, and optically-interfaced high-speed routers. Cogent has been recognized as the first IP+Optical Cisco Powered Network (CPN). Cogent is currently servicing 20 metropolitan markets. Cogent Communications is headquartered at 1015 31st Street, NW, Washington, D.C. 20007. For more information, visit www.cogentco.com. Cogent Communications can be reached at (202) 295-4200 or via email at info@cogentco.com. # # # 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 statement on Form S-4 as amended by a Form S-4/A (Amendment No. 8) filed with the Securities and Exchange Commission ("SEC") on January 8, 2002, and in our other reports filed from time to time with the SEC.