QUESTIONS AND ANSWERS ABOUT THE MERGER

Q: Why are Cogent and Allied Riser proposing the merger?

A: Cogent and Allied Riser are proposing the merger because it presents an opportunity for us to combine the unique networks we have constructed to create a leading provider of broadband data and video services to small- and medium-sized businesses. Following the merger, we will be a company with greater operational efficiencies, earning power, and financial resources. We expect to become a stronger competitor in the telecommunications services business and expect that our financial performance will benefit from the combination of our businesses.

Q: What is the proposed transaction?

A: Cogent will acquire Allied Riser under a merger agreement providing that a wholly owned subsidiary of Cogent, which we call the merger subsidiary, will merge with and into Allied Riser. As a result of the merger, Allied Riser will become a wholly owned subsidiary of Cogent.

Q: What will I receive in the merger?

A: If the merger is completed and Cogent does not issue any of its common stock in other transactions between now and the date the merger is completed, you will receive 0.0321780 shares of Cogent common stock for each share of Allied Riser common stock that you own. If the merger is completed and, between now and the date the merger is completed, Cogent issues additional shares of its common stock in other transactions, you will receive a lesser number of shares, but no fewer than 0.031756 shares, of Cogent common stock for each share of Allied Riser common stock. Cogent will not issue fractional shares of its common stock. Instead, any otherwise fractional share will be rounded up to a whole share. The number of shares you will receive reflects a one for ten reverse stock split of Cogent that we expect to occur immediately prior to the consummation of the merger. For a description of the rights of Cogent common stockholders, see "Description of Cogent Capital Stock."

Q: What are the U.S. Federal Income Tax consequences of the merger?

A: The merger is intended to qualify as a tax-free reorganization under the Internal Revenue Code. Accordingly, no gain or loss will be recognized by Cogent, Allied Riser, or the merger subsidiary. Additionally, no gain or loss will be recognized by Allied Riser stockholders to the extent they receive shares of Cogent common stock in the merger. However, Allied Riser stockholders should consult their tax advisors for a full understanding of the tax consequences of the merger.

Q: Does the Allied Riser board of directors recommend approval of the merger?

A: Yes. After careful consideration, the board of directors of Allied Riser unanimously recommends that Allied Riser stockholders vote "FOR" adoption of the merger agreement, as amended, and approval of the merger. For a more complete description of the recommendation of the Allied Riser board of directors, see the section entitled "The Merger—Recommendation of the Allied Riser Board of Directors; Allied Riser's Reasons for the Merger" on page 33.

Q: What should I do now?

A: Please carefully read and consider the information contained in this document. If you are currently an Allied Riser stockholder, please complete, sign, and mail your proxy card in the enclosed postage-prepaid return envelope as soon as possible so that your shares of Allied Riser common stock may be represented at the special meeting. Alternatively, you can simplify your voting by voting your shares via telephone or the Internet. The telephone and Internet voting procedures, which are set forth in this proxy statement/prospectus, are designed to authenticate your identity, allow you to vote your shares, and confirm that your instructions have been properly recorded. If you elect to vote over the Internet, you may incur costs such as telecommunication and Internet access charges. The Internet and

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telephone voting facilities for stockholders of record will close at 4:00 p.m. Eastern Time on the evening before the special meeting. In order to ensure that your shares are voted, please give your proxy in accordance with the instructions on your proxy card even if you currently plan to attend the special meeting and vote in person. For a more complete description of the voting procedures, see the section entitled "Allied Riser Special Meeting—Proxies" on page 26.

Q: What if I don't vote?

A: If you do not submit a proxy or instruct your broker to vote your shares, and you do not vote in person at the special meeting, the effect will be the same as if you voted "AGAINST" the adoption of the merger agreement, as amended, and approval of the merger.

Q: If my shares are held in "street name" by my broker, will my broker vote my shares for me?

A: Your broker will not be able to vote your shares without instructions from you on how to vote. Therefore, it is important that you follow the directions provided by your broker regarding how to instruct your broker to vote your shares. If you fail to provide your broker with instructions, it will have the same effect as a vote "AGAINST" the adoption of the merger agreement, as amended, and approval of the merger. If your shares are held in the name of a bank or broker, the availability of telephone and Internet voting will depend on the voting processes of the bank or broker; therefore, you should follow the voting instructions on the form you receive from your bank or broker.

Q: Can I change my vote or election after I have delivered my proxy or election?

A: Yes. You can change your vote at any time before your proxy is voted at the special meeting. You can do this in one of three ways. First, you can revoke your proxy. Second, you can submit a new proxy. If you choose either of these two methods and you are a holder of record, you must submit your notice of revocation or your new proxy to the Secretary of Allied Riser before the special meeting. However, if your shares are held in a street name account at a brokerage firm or bank, you should contact your brokerage firm or bank to change your vote. Third, if you are a holder of record, or if your shares are held in street name and you receive a valid proxy from your broker, you can attend the special meeting and vote in person.

Q: Should I send in my Allied Riser stock certificates now?

A: No. After we complete the merger, an exchange agent on behalf of Cogent will send instructions to Allied Riser stockholders whose shares were converted in the merger. These instructions will explain how to exchange your Allied Riser stock certificates for the appropriate Cogent stock certificates. Cogent stockholders will continue to own their shares of Cogent common stock after the merger and should continue to hold their stock certificates.

Q: Who can help answer my questions?

A: If you have any questions about the merger or how to submit your proxy, or if you need additional copies of this proxy statement/prospectus or the enclosed proxy cards or voting instructions, you should contact Allied Riser's proxy solicitation agent.

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THE MERGER

General

    Each of the Allied Riser board of directors and the Cogent board of directors has approved the merger agreement and the merger. Cogent will acquire Allied Riser under a merger agreement providing that a wholly owned subsidiary of Cogent that we call the merger subsidiary will be merged with and into Allied Riser. As a result of the merger, Allied Riser will become a wholly owned subsidiary of Cogent.

Background of the Merger

    In July 1997, prior to founding Cogent, Dave Schaeffer, the chief executive officer and founder of Cogent, had a meeting with Todd Doshier, a founder of Allied Riser. At this meeting, Mr. Doshier presented the initial Allied Riser plan to Mr. Schaeffer. This plan entailed the construction of in-building fiber-optic distribution systems for sale or lease to other carriers. Over the next several months, Mr. Doshier and Mr. Schaeffer had several informal phone conversations to discuss the development of Allied Riser's business.

    Mr. Schaeffer founded Cogent in August 1999. Over the next two years, Mr. Schaeffer continued to monitor the development of Allied Riser's business, including its initial public offering in October 1999.

    In April 2000, Mr. Schaeffer met David Crawford, the then chief executive officer of Allied Riser, in an investor panel discussion. Mr. Schaeffer and Mr. Crawford had two telephone conversations exploring possible opportunities between the two companies. At that time, they concluded that there was no immediate opportunity for the two companies to work together because of the competitive environment. Over the next 15 months, Cogent continued to monitor the progress of Allied Riser and was aware of the change from the primary provision of retail telecommunication services to the primary provision of wholesale in-building facilities to other telecommunication providers that Allied Riser was undertaking in light of the difficult market conditions for competitive broadband communications service providers.

    During the third quarter of 2000, Allied Riser implemented certain cost-cutting initiatives, including a reduction in force and the investigation of possible strategic alternatives for the company. Allied Riser consulted its financial advisors and other strategic advisors regarding a variety of possible options for the company. During the fourth quarter of 2000 and into the first quarter of 2001, Allied Riser had intermittent discussions with a third party regarding a possible combination of the third party and Allied Riser. The discussions were terminated when the parties could not agree on terms of a transaction. Following termination of these discussions, Allied Riser continued its efforts to reduce costs and began to investigate the possibility of a financial restructuring, including the purchase of its 7.50% convertible subordinated notes due 2007. On June 12, 2001, Allied Riser announced the completion of a tender offer, accepting for purchase $26,400,000 in aggregate principal amount of the notes, representing approximately 17.6% of the $150,000,000 aggregate principal amount of the notes outstanding prior to the tender offer.

    In July 2001, Allied Riser retained Houlihan Lokey Howard & Zukin to assist Allied Riser in further evaluating possible strategic alternatives. On July 12, 2001 Houlihan Lokey representatives made a presentation to the Board of Directors of Allied Riser regarding Houlihan Lokey's analysis of possible strategic alternatives, including the purchase of additional outstanding notes, divestitures of Allied Riser's unprofitable operations, and realization of tax efficiencies. At approximately the same time Allied Riser began discussions with its vendors to restructure Allied Riser's obligations and reduce its liabilities. On July 24, 2001, Allied Riser announced that it was suspending its retail business and refocusing its resources on providing wholesale in-building facilities and announced that it would

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terminate the employment of approximately 75% of its remaining workforce over the following 60 to 75 days.

    In contemplating additional alliances and partnerships, Cogent's management team decided to explore a potential strategic relationship with Allied Riser. On August 4, 2001, following a preliminary call to Mr. Dinsmore by Mr. Schaeffer suggesting that they meet, Cogent and Allied Riser entered into a confidentiality agreement relating to the discussions of a potential merger. On August 7, 2001, Mr. Schaeffer and Mr. Dinsmore again spoke by telephone and discussed a possible strategic alliance and potential structural scenarios.

    On August 8, 2001, Mr. Schaeffer met with Mr. Dinsmore in Dallas and continued their discussions regarding the business strategies and objectives of Cogent and Allied Riser, the condition of each company and the possibility of a combination of Cogent and Allied Riser. A stock-for-stock merger proposal was discussed in a meeting between Mr. Schaeffer and Mr. Dinsmore on August 10, 2001 in Dallas. During the discussion on August 10, Mr. Dinsmore advised Mr. Schaeffer of the importance of receipt by Allied Riser's stockholders of Cogent common stock with a value in excess of the recent market capitalization of Allied Riser and they discussed the previously anticipated issuance by Cogent of preferred stock in a separate private placement. Messrs. Dinsmore and Schaeffer discussed an equity valuation of Allied Riser of approximately $20 million. Mr. Schaeffer and Mr. Dinsmore agreed that the merger proposal and equity valuation had merit and that each party would discuss the opportunity with his respective board.

    On August 10, 2001, the directors of Allied Riser met by telephone conference call and Mr. Dinsmore advised them of the contact by Mr. Schaeffer and the possible acquisition of Allied Riser by Cogent. Mr. Dinsmore described the discussions with Mr. Schaeffer and outlined for the Allied Riser board the general parameters of the proposed transaction. After a discussion by the directors of Cogent's proposal, the board authorized senior management of Allied Riser to conduct a due diligence review of Cogent and to negotiate a business combination with Cogent with the conditions that no decision to pursue such a transaction could be made without the approval of the directors and that Mr. Dinsmore report to the board any developments that resulted from such negotiations.

    Upon initial consultation with Cogent's board members, Cogent management believed additional due diligence was warranted. On August 11, 2001, management of both companies agreed to conduct due diligence reviews of each other.

    On August 12, 2001, a meeting between Allied Riser and Cogent was held at Cogent's offices in Washington, D.C. This meeting included Michael Carper, general counsel of Allied Riser, and Quen Bredeweg, chief financial officer of Allied Riser; Amit Patel and Andrew Morrow from Houlihan Lokey Howard & Zukin; Helen Lee, chief financial officer of Cogent, and Mr. Schaeffer. During this meeting, certain due diligence items were exchanged and discussed and the participants explored how the businesses might complement each other and how to structure the transaction. Over the next several days, Mr. Schaeffer and Mr. Dinsmore had a series of telephonic discussions that concluded with the determination that both companies should move forward with the proposed combination. Cogent engaged Latham & Watkins to assist in these matters, Allied Riser retained Jones, Day, Reavis & Pogue to assist Allied Riser in this transaction.

    On August 13, 2001, the Allied Riser board met again by telephone conference call to discuss events since the previous meeting of directors. Mr. Dinsmore described the principal issues that had been raised in the discussions with Cogent, including the proposed financial terms of the combination and the receipt by Allied Riser stockholders of Cogent common stock, the current financial condition of each of Allied Riser and Cogent, the effects on Allied Riser of a business combination with Cogent, and the valuation of Cogent, including the anticipated issuance by Cogent of its Series C preferred stock. The Board also discussed other possible strategic alternatives that might be available to Allied

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Riser. At the conclusion of the meeting, the directors approved further discussions by Allied Riser's senior management with representatives of Cogent.

    On August 14 and 15, 2001, representatives of Cogent met with Allied Riser representatives in Allied Riser's offices in Dallas, Texas and conducted additional due diligence review regarding Allied Riser.

    During the period between August 16, 2001 and August 19, 2001, Allied Riser and its financial and legal advisors completed a due diligence review of Cogent and its operations and financial condition. On August 18 and 19, 2001, senior executives of both Cogent and Allied Riser and their respective legal advisors met at Latham & Watkins in Washington, D.C. and continued to negotiate the terms of a definitive agreement.

    On August 20, 2001, the Allied Riser board met again by telephone conference call and Mr. Dinsmore discussed with the directors the retention of Houlihan Lokey as Allied Riser's financial advisor in connection with the merger. The directors authorized management to finalize the agreement with Houlihan Lokey. Mr. Dinsmore advised the directors with respect to the terms of the merger agreement being negotiated with Cogent. Representatives of Jones, Day, Reavis & Pogue also advised the directors regarding certain legal matters. The board discussed the proposed transaction, including the structure of the transaction and potential impediments to consummation of the merger.

    On August 20, 2001, a special meeting of the board of directors of Cogent was held to discuss this opportunity. Mr. Schaeffer and Ms. Lee discussed the progress of the negotiations with Allied Riser and presented an analysis of the proposed combination from a financial point of view. Following extensive discussions and after five teleconferences over the next several days, the Cogent board of directors unanimously approved the merger agreement and the merger on August 27, 2001.

    On August 27, 2001 the Allied Riser board met by telephone conference call to discuss the status of the proposed merger agreement and to be advised by Houlihan Lokey as to its financial analysis of the proposed merger. After a presentation by representatives of Houlihan Lokey, the directors discussed issues raised by the Houlihan Lokey presentation and requested additional information from Houlihan Lokey to permit due consideration of the merger. The board adjourned the meeting with agreement to reconvene the following day. On August 28, 2001, the Allied Riser directors met by telephone conference call and representatives of Houlihan Lokey made a presentation regarding the financial analysis they had performed with respect to the possible business combination with Cogent. Legal counsel advised the directors with respect to changes in the proposed terms of the merger agreement since the board's meeting of August 20 and other legal matters. The directors then discussed the proposed transaction and asked questions of the legal and financial advisors. At the conclusion of the discussions, a representative of Houlihan Lokey orally informed the Allied Riser board, which oral advice was subsequently confirmed in writing, that in Houlihan Lokey's opinion, the merger and exchange of Allied Riser shares as provided in the merger agreement were fair to the Allied Riser stockholders from a financial point of view, and fair to the Allied Riser creditors (on an aggregate basis) from a financial point of view. At that point, the representatives of Houlihan Lokey and legal counsel were excused from the meeting and the directors further discussed the possible transaction. At the conclusion of these discussions, the Allied Riser board unanimously approved the merger agreement and the related transactions.

    Cogent and Allied Riser then executed the merger agreement and issued a joint press release the following morning.

    On September 24, 2001, the Allied Riser board met by telephone conference call to discuss, among other things, the status of the proposed merger with Cogent, including the status of Cogent's issuance of its Series C preferred stock. On October 1 and 2, Mr. Schaeffer and Mr. Dinsmore met in Dallas to discuss the progress of the merger. Since the execution of the merger agreement, Cogent had acquired

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certain assets and liabilities of NetRail, Inc., and Allied Riser had made substantial progress in negotiating with various creditors and vendors regarding the settlement and termination of certain agreements. In addition, the financial markets had materially deteriorated, particularly for the stocks of communications companies. Given the occurrence of these events and Cogent's and Allied Riser's desire to file this proxy statement/prospectus promptly, Mr. Schaeffer and Mr. Dinsmore agreed to consider an amendment to the merger agreement to provide, among other things that (1) this proxy statement/prospectus would be filed by a specific date, (2) Cogent would complete the issuance of its Series C preferred stock by a specific date, and (3) Allied Riser would have additional flexibility to restructure or terminate certain agreements.

    On October 4, 2001, the Allied Riser board met by telephone conference call to discuss the proposed amendment to the merger agreement. Mr. Dinsmore described certain changes in circumstances that had occurred since the signing of the merger agreement, including the decrease in the anticipated issuance of Cogent's Series C preferred stock from approximately $130 million to approximately $65 million and Allied Riser's success in negotiating a reduction of its capital lease obligations. Mr. Dinsmore further described the status of Allied Riser's initiatives regarding reduction of its costs and of discussions regarding the terms of the proposed amendment to the merger agreement, including an increase in the amount of Cogent stock to be received by the Allied Riser stockholders in the merger, the obligations of Cogent to complete the issuance of its Series C preferred stock, and of Cogent and Allied Riser to file the proxy statement/prospectus by specific dates, and the increase in the amount of cash expenditures that Allied Riser would be permitted to make during the fourth quarter 2001, the designation by Allied Riser of an additional director to Cogent's board, and various other minor provisions. The directors then discussed the proposed amendment. At the conclusion of the discussion, the directors present authorized management to complete negotiation of the proposed amendment.

    Management of both companies continued to discuss certain provisions of the proposed amendment.

    On October 10, 2001, the Allied Riser board met by telephone conference call. Mr. Dinsmore detailed the terms of the proposed amendment to the merger agreement, including, without limitation:

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increasing the valuation of Allied Riser common stock to $25.0 million;



•

Cogent's agreement not to consummate a Rule 13e-3 transaction or otherwise acquire, directly or indirectly, more than 80% of the Cogent common shares issued in the merger prior to six months after the effective time of the merger;



•

increasing Allied Riser's authorized company cash expenditures by $5.0 million for the fourth quarter of 2001;



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Cogent's commitment not to acquire or agree to acquire a material business or person prior to the effective time of the merger;



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permitting Allied Riser to terminate the merger agreement if this proxy statement/prospectus shall not have been filed with the SEC on or prior to October 16, 2001;



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permitting Allied Riser to terminate the merger agreement if Cogent shall not have issued at least $62.0 million of its Series C preferred stock for cash on or prior to October 17, 2001; and



•

elimination of the lockup agreements that, under the merger agreement, were to be executed by certain stockholders of Allied Riser.

    Following discussions of the terms of the proposed amendment, the board authorized Mr. Dinsmore and the other members of senior management to continue the negotiations and to finalize an amendment to the merger agreement.

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    On October 11, 2001 Cogent's board of directors met by telephone to consider, among other matters, the status of the merger with Allied Riser. The board reviewed with management the current terms of the amendment under discussion and confirmed management's authorization to negotiate and enter into an amendment to the merger agreement.

    Management of both companies continued to negotiate final provisions in the proposed amendment to the merger agreement. On October 13, 2001, Cogent and Allied Riser executed the amendment to the merger agreement.

Recommendation of the Allied Riser Board of Directors; Allied Riser's Reasons for the Merger

    The Allied Riser board of directors believes that the merger is in the best interests of Allied Riser's stockholders and has unanimously approved the merger agreement and declared it to be advisable, and unanimously recommends that Allied Riser stockholders vote "FOR" adoption of the merger agreement, as amended, and approval of the merger.

    In reaching its decision, the Allied Riser board of directors consulted with Allied Riser's management and its financial and legal advisors, and considered a variety of factors, including the following:

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the per share merger consideration in relation to recent market trading prices for Allied Riser common stock and the fact that the merger consideration represents, as of August 28, 2001, a premium of over 100% based on the closing sales price for the Allied Riser common stock;



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Cogent's covenant not to go private for a period of six months following the effective time of the merger;



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conditions in the telecommunications services industry and Allied Riser's business, operations, financial condition, earnings, and prospects as an independent company;



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the anticipated financial resources of the combined entity, given the expected debt and equity sources of capital following consummation of the merger;



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the trend of further consolidation in the telecommunications industry and the decreasing number of available strategic partners for Allied Riser;



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significant declines in the valuation of competitive telecommunications providers, continued weakness in the demand for information and technology and telecommunications services, and business failures of several prominent companies in markets similar to Allied Riser's;



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Allied Riser's prospects as an independent company, the constraints on Allied Riser's ability to pursue its strategic objectives due to its limited access to capital and its present size, and the belief that Allied Riser's prospects would be enhanced by the merger;



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the ability of Allied Riser to effect a restructuring of its current debt and the possible values to be realized in the event of a possible liquidation;



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the opportunity for Allied Riser stockholders to participate in a company with greater financial resources and access to capital and long term contracts to use nationwide fiber-optic intercity and intra-city networks;



•

the opinion of Houlihan Lokey that, as of the date of its opinion, the merger and the exchange of Allied Riser shares as provided in the merger agreement were fair to the Allied Riser stockholders and fair to Allied Riser's creditors (on an aggregate basis) from a financial point of view and the fact that the opinion of Houlihan Lokey was not updated in connection with the amendment to the merger agreement or the material events or changes in circumstances that occurred after August 28, 2000 that would have affected the analysis of Houlihan Lokey as to

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the fairness of the merger from a financial point of view and the opinion delivered by Houlihan Lokey on August 28, 2001. See "—Opinion of Allied Riser's Financial Advisor;"

•

the anticipated effectiveness of the merger in implementing Allied Riser's strategy to provide in-building services utilizing its broadband data network;



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the potential increased scale, scope, and financial strength of the combined company, the potential greater liquidity of the combined company and the combined company's potential for increased access to capital;



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the business, operations, financial condition, earnings, and prospects of Allied Riser and Cogent, taking into account the results of Allied Riser's due diligence review of Cogent;



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the anticipated financial impact of the proposed transaction on the combined company's financial performance, including the resulting company's capital structure;



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the complementary nature of the businesses of Allied Riser and Cogent;



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the structure of the merger and the financial and other terms of the merger agreement;



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the ability of Allied Riser under certain conditions to consider unsolicited alternative proposals, its ability to terminate the merger agreement under certain conditions, and the termination fees payable on certain termination events;



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the ability of Allied Riser as an independent company to remain listed on a national securities exchange; and



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the anticipated tax treatment of the merger.

    Allied Riser's board of directors also identified and considered a variety of potentially negative factors in its deliberations concerning the merger, including the following:

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the risk that the potential benefits in the merger might not be fully realized;



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the possibility that the merger might not be consummated and the effect of the public announcement of the merger on Allied Riser's customers, creditors, and employees;



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the likelihood that Cogent would complete its issuance of preferred stock and receive certain consents, as set forth in the merger agreement;



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the fact that Cogent has been in business for a limited time, has limited revenues, and has yet to earn a profit;



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as described on pages 43 and 44 of this proxy statement/prospectus, and by virtue of certain indemnification rights, change of control arrangements, and accelerated vesting of stock options, restricted shares, and deferred share units, the fact that certain members of Allied Riser's board of directors and management might have interests in the merger that are different than those of other Allied Riser stockholders;



•

the risk of possible delays associated with the completion of the merger; and



•

the other risks described under "Risk Factors" beginning on page 13 of this proxy statement/prospectus.

    The foregoing discussion of the information and factors considered by the Allied Riser board of directors is not exhaustive, but includes the material factors considered by the Allied Riser board of directors. The Allied Riser board of directors did not quantify or assign any relative or specific weights to the various factors that it considered. Rather, the Allied Riser board of directors based its recommendation on the totality of the information presented to and considered by it. In addition,

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individual members of the Allied Riser board of directors may have given differing weights to different factors.

    The Allied Riser board of directors unanimously recommends that Allied Riser stockholders vote "FOR" the adoption of the merger agreement and approval of the merger.

Opinion of Allied Riser's Financial Advisor

    Allied Riser initially retained Houlihan Lokey in July 2001, to advise the board regarding Allied Riser's business and possible strategic alternatives. Houlihan Lokey subsequently was retained by the Allied Riser board of directors to analyze the fairness of the merger from a financial point of view to stockholders and creditors (on an aggregate basis) of Allied Riser. It was Houlihan Lokey's understanding that the opinion with respect to the creditors was being delivered solely as a condition to the merger agreement as it existed on August 28, 2001 without regard to subsequent amendments. Houlihan Lokey is a nationally recognized investment banking firm that provides financial advisory services in connection with mergers and acquisitions, leveraged buyouts, business valuations for a variety of regulatory and planning purposes, recapitalizations, financial restructurings, and private placements of debt and equity securities.

    At the meeting of the Allied Riser board of directors on August 28, 2001, Houlihan Lokey rendered its oral opinion, subsequently confirmed in writing, that as of August 28, 2001, and subject to and based upon the various qualifications and assumptions set forth in its written opinion, the consideration to be received by the stockholders of Allied Riser in connection with the merger as described in the merger agreement as it existed on August 28, 2001 without regard to subsequent amendments was fair, from a financial point of view, to Allied Riser's stockholders, as well as to Allied Riser's creditors on an aggregate basis. The full text of Houlihan Lokey's written opinion, dated August 28, 2001, to the board of directors, which sets forth the assumptions made, general procedures followed, factors considered and limitations on the review undertaken, is attached as Appendix C, and is incorporated herein by reference. This summary is qualified in its entirety by reference to the full text of such opinion. Stockholders and creditors of Allied Riser are urged to, and should, read the opinion in its entirety. The engagement of Houlihan Lokey and its opinion are for the benefit of Allied Riser's board of directors. Houlihan Lokey undertook no obligation to update its opinion following its delivery on August 28, 2001 and no such update was requested or received by the board of directors in connection with the approval of the directors of the amendment to the merger agreement or the material events or changes in circumstances that occurred after August 28, 2001, which would have affected the analysis of Houlihan Lokey as to the fairness of the merger from a financial point of view and the opinion delivered by Houlihan Lokey on August 28, 2001.

    Houlihan Lokey did not, and was not requested by Allied Riser to, make any recommendations as to the form or amount of consideration to be received by the Allied Riser stockholders, the market value or realizable value of Cogent common stock given as consideration in the merger, the prices at which Cogent common stock may sell in the future following the merger, or the tax or legal consequences of the merger, and Houlihan Lokey does not express any opinion as to the fairness of any aspect of the merger not expressly addressed in its fairness opinion. Allied Riser agreed to indemnify Houlihan Lokey and its affiliates against certain liabilities, including liabilities under federal securities laws that arise out of the engagement of Houlihan Lokey.

    Houlihan Lokey's opinion did not address Allied Riser's underlying business decision to effect the merger. Houlihan Lokey was not been requested to, and did not, solicit third party indications of interest in acquiring all or any part of Allied Riser. Furthermore, Houlihan Lokey has not negotiated the merger.

    The opinion did not constitute a recommendation to the board of directors as to whether or not to support the merger and recommend it to Allied Riser's stockholders and did not and does not

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constitute a recommendation to Allied Riser stockholders as to whether or not to vote in favor of the merger.

Matters Reviewed

    In arriving at its opinion, among other things, Houlihan Lokey:

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reviewed Allied Riser's annual report on Form 10-K for the fiscal year ended December 31, 2000 and quarterly reports on Form 10-Q for the quarters ended March 31, 2001, and June 30, 2001, which Allied Riser's management identified as being the most current financial statements available;



•

reviewed Cogent's audited financial statements for the fiscal year ended December 31, 2000 and Cogent's unaudited interim financial statements for the six months ended June 30, 2001, which Cogent's management identified as being the most current financial statements available;



•

reviewed the form of the merger agreement as it existed on August 28, 2001 without regard to subsequent amendments;



•

reviewed copies of the following agreements: (i) Indenture to the Company's 7.5% Convertible Subordinated Notes due 2007, (ii) Master Agreement to Lease Equipment with Cisco Systems Capital Corporation, (iii) various Transit Agreements (e.g. AT&T, Sprint, Qwest, etc.), (iv) various Telecommunications License Agreements, (v) Cogent's Series A Participating Convertible Preferred Stock Purchase Agreement, (vi) Cogent's Series B Participating Convertible Preferred Stock Purchase Agreement, and (vii) Cogent's Summary of Terms for its proposed issuance of Series C Preferred Stock as of August 9, 2001;



•

met with certain members of the senior management of Allied Riser and Cogent to discuss the merger as well as the operations, financial condition, future prospects and projected operations and performance of Allied Riser and Cogent;



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reviewed forecasts and projections prepared by Allied Riser's management with respect to Allied Riser for the years ended December 31, 2001 through 2006;



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reviewed forecasts and projections prepared by Cogent's management with respect to Cogent for the years ended December 31, 2001 through 2011;



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reviewed the historical market prices and trading volume for Allied Riser's publicly traded securities;



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reviewed certain other publicly available financial data for certain companies that Houlihan Lokey deemed comparable to Allied Riser;



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reviewed drafts of certain documents to be delivered at the closing of the merger;



•

conducted such other studies, analyses and inquiries as Houlihan Lokey deemed appropriate.

Assumptions and Limitations

    Houlihan Lokey's opinion was based on the business, economic, market, and other conditions that existed as of August 28, 2001. Houlihan Lokey relied upon and assumed, without independent verification, that the financial forecasts and projections provided to it by Allied Riser and Cogent had been reasonably prepared and reflected the best currently available estimates of the future financial results and condition of Cogent and Allied Riser, and that there had been no material change that had not been disclosed to it by Allied Riser and Cogent in the assets, financial condition, business or prospects of Cogent or Allied Riser since the date of the most recent financial statements made available to it.

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    Houlihan Lokey did not independently verify the accuracy and completeness of the information supplied to it with respect to Cogent or Allied Riser and did not assume any responsibility with respect to it. Houlihan Lokey did not make any physical inspection or independent appraisal of any of the properties or assets of Cogent or Allied Riser. Houlihan Lokey's opinion is necessarily based on business, economic, market and other conditions as they existed and could be evaluated by it at the date of the opinion.

    The conclusion resulting from the analyses indicated that as of the date such opinion was rendered, the merger as described in the merger agreement as it existed on August 28, 2001, was fair to the stockholders of Allied Riser from a financial point of view and fair to Allied Riser's creditors (on an aggregate basis) from a financial point of view. Houlihan Lokey undertook no obligation to update its opinion following its delivery on August 28, 2001 and no such update was requested or received by the board of directors in connection with the approval by the directors of the amendment to the merger agreement or the material events or changes in circumstances that occurred after August 28, 2001, which would have affected the analysis of Houlihan Lokey as to the fairness of the merger from a financial point of view and the opinion delivered by Houlihan Lokey on August 28, 2001.

Valuation of Cogent Communications Group, Inc.

    The following is a summary of the material financial analyses performed by Houlihan Lokey in connection with rendering its fairness opinion on August 28, 2001 to the Allied Riser board of directors. Houlihan Lokey used several methodologies to assess the fairness, from a financial point of view, of the consideration to be received by the Allied Riser stockholders in the merger as described in the merger agreement as it existed on August 28, 2001, without regard to subsequent amendments. Each methodology provided an estimate as to the aggregate value of the equity Allied Riser stockholders will receive in the merger. The summary of the financial analyses was not a complete description of the analyses performed by Houlihan Lokey. The Houlihan Lokey opinion is based upon the totality of the various analyses performed by Houlihan Lokey and reliance on any particular portion of the analyses without considering all analyses and factors could create a misleading or incomplete view of the process underlying the opinion.

     Comparable Company Analysis.

    Using publicly available information, Houlihan Lokey compared selected financial data of Cogent with similar data of selected companies engaged in businesses considered by Houlihan Lokey to be comparable to that of Cogent. Houlihan Lokey included in its selected comparable companies Broadwing Inc., Focal Communications Corp., Genuity Inc., Level 3 Communications, Inc., Metromedia Fiber Network, Inc., SAVVIS Communications Corp., Time Warner Telecom Inc., Williams Communications Group, and XO Communications, Inc. The purpose of the comparable company analysis was to establish a range for the potential equity value of Cogent, by selecting certain operating results commonly used in the public equity markets to value the comparable companies and applying a range of multiples to similar projected operating results of Cogent.

    Inherent differences exist between the businesses, operations and prospects of Cogent and the comparable companies. Accordingly, Houlihan Lokey believed that it was inappropriate to, and therefore did not, rely solely on the above-described quantitative results of the comparable company analysis and accordingly also made qualitative judgments concerning differences between the financial and operating characteristics and prospects of Cogent and the comparable companies that would, in Houlihan Lokey's opinion, affect the public market valuation of such companies.

     Discounted Cash Flow Analysis

    Based upon projections furnished by Cogent management, Houlihan Lokey performed a discounted cash flow analysis, calculating the debt-free cash flows ( i.e. , cash flows before payments

37

made to equity investors and holders of interest-bearing debt) that Cogent expected to generate for the fiscal years ending December 31, 2001 through 2006. Houlihan Lokey also calculated a range of terminal values for Cogent at the conclusion of a five-year period ending in 2006. In calculating this range in terminal value, Houlihan Lokey used terminal multiples ranging from 4.5 to 5.5 times projected fiscal 2006 EBITDA. Houlihan Lokey then discounted these debt-free cash flows and the range of these terminal values to the present using a range of discount rates from 45% to 55%. Houlihan Lokey selected these discount rates based on assumed rates of return necessary to justify an investment in comparable, late-stage venture capital companies.

     New Money Valuation Analysis

    Houlihan Lokey reviewed the summary of terms for the proposed issuance by Cogent of its Series C Preferred Stock to a group of third-party investors. As of August 28, 2001, Houlihan Lokey was advised that Cogent was in the process of negotiating a private placement of $130 million in Series C Preferred Stock. Such shares were being valued based on arms length negotiations between Cogent and a group of investors.

    Houlihan Lokey drew no specific conclusion from its comparable company, discounted cash flow and new money valuation analyses, but subjectively factored its observations from these analyses into its qualitative assessment of the facts and circumstances relevant to its opinion.

     Debt Assumption Analysis

    Houlihan Lokey analyzed assumed trading values and potential recoveries for creditors under the combined entity to assess the fairness of the merger as it existed on August 28, 2001 without regard to subsequent amendments with respect to creditors on an aggregate basis. Houlihan Lokey assessed the risk profile and leverage of the combined entity to determine appropriate rates of return for creditors of the merged entity. Such required rates of return were applied to the current contractual obligations of Allied Riser. Houlihan Lokey used such analysis to determine the value of debt obligations under the combined entity.

Review of Strategic Alternatives to the Merger

    In evaluating the fairness for Allied Riser's stockholders, as well as Allied Riser's creditors on an aggregate basis, Houlihan Lokey considered the expected value to Allied Riser's stockholders and creditors of completing the merger and certain alternatives to the merger, in each case, as described in the merger agreement as it existed on August 28, 2001 without regard to subsequent amendments and material events that occured after August 28, 2001. With regard to each alternative, Houlihan Lokey's analysis qualitatively considered the valuation implications to the stockholders, the probability of successfully completing the alternatives, and the cost and time to implement the alternatives. For purposes of this analysis, Houlihan Lokey considered the following strategic alternatives: (1) pursuit of a wholesale model providing in-building access to other carriers and subsequent bankruptcy at year end 2002; (2) negotiated out-of-court debt restructuring and liquidation; and (3) immediate filing for Chapter 11 bankruptcy protection. Houlihan Lokey noted that of the strategic alternatives considered, the merger as described in the merger agreement as it existed on August 28, 2001 without regard to subsequent amendments and material events that occured after August 28, 2001 appeared to provide the greatest value to Allied Riser's stockholders and creditors (on an aggregate basis) on a risk-adjusted basis.

Conclusion

    The summary set forth above describes the material points of more detailed analyses performed by Houlihan Lokey in arriving at its fairness opinion. The preparation of a fairness opinion is a complex analytical process involving various determinations as to the most appropriate and relevant methods of

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financial analysis and application of those methods to the particular circumstances and is therefore not readily susceptible to summary description. In arriving at its opinion, Houlihan Lokey made qualitative judgments as to the significance and relevance of each analysis and factor. Accordingly, Houlihan Lokey believes that its analyses and summary set forth herein must be considered as a whole. In its analysis, Houlihan Lokey made numerous assumptions with respect to Cogent, Allied Riser, industry performance, general business, economic, market and financial conditions and other matters, many of which are beyond the control of management of either company. The estimates contained in such analyses are not necessarily indicative of actual values or predictive of future results or values, which may be more or less favorable than suggested by such analyses. Additionally, analyses relating to the value of businesses or securities are not appraisals. Accordingly, such analyses and estimates are inherently subject to substantial uncertainty. You should carefully read this summary in conjunction with the opinion letter dated August 28, 2001 which is included as Appendix C to this proxy statement/prospectus.

    In accordance with the terms of its engagement letter and in addition to the fees payable by Allied Riser to Houlihan Lokey pursuant to its initial engagement, Allied Riser agreed to pay Houlihan Lokey a fee of $700,000, plus reasonable out-of-pocket expenses, for its preparation and delivery of the fairness opinion. No portion of Houlihan Lokey's fee is contingent upon the opinion of the merger being favorable or upon the successful completion of the merger. Allied Riser has also agreed to indemnify Houlihan Lokey against certain liabilities, including liabilities under the federal securities laws, relating to or arising out of the engagement of Houlihan Lokey. In addition, Allied Riser has entered into an amendment to the merger agreement based on certain changes in circumstances that have occurred since the Houlihan Lokey opinion was delivered. Such changed circumstances were not considered in the opinion and would have affected the analysis and/or conclusions reached by Houlihan Lokey, if Houlihan Lokey had been requested to update its opinion.

Recommendation of the Cogent Board of Directors; Cogent's Reasons for the Merger

    The Cogent board of directors has unanimously adopted and approved the merger agreement and has recommended approval of the merger to its stockholders. In the course of reaching its decision to adopt and approve the merger agreement and the merger and to recommend approval to its stockholders, the Cogent board of directors consulted with legal advisors and considered a number of factors, including, among others, the following principal factors that were material to the decision:

•

current industry, market and economic conditions, including the continuing trend of consolidation in the telecommunications industry and the importance of operational sales in remaining competitive in the long term;



•

the strategic fit between the two companies and the potential for a combined company with greater financial and operational strength, including the belief that the combined company's stronger balance sheet will enable it to accelerate execution of its business plan, effect capital expenditure cost savings, and enhance the combined company's access to capital;



•

the complementary nature of the companies' network footprint and service offerings;



•

common technology platform and operational support systems;



•

the operating efficiencies of the combined company; and



•

the financial condition of the combined company after the transaction, including its pro forma market capitalization, revenues, and potential profits and earnings.

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    In the course of deliberations, Cogent also considered a number of additional factors relevant to the merger, including:

•

the possibility of strategic alternatives to the merger for enhancing long-term stockholder value, including investigating strategic transactions with other companies;



•

the ownership of the combined enterprise by Cogent stockholders and former Allied Riser stockholders;



•

the potential for an increase or decrease in the market price of the combined company;



•

the potential for improved trading liquidity for stockholders of the combined company;



•

the terms and conditions of the merger agreement, including the termination fees and the "fiduciary duty outs," the agreements contemplated by the merger agreement, and the closing conditions;



•

the expected qualification of the merger as a reorganization under section 368(a) of the Internal Revenue Code;



•

the impact of the merger on Cogent and Allied Riser customers, suppliers, and employees;



•

the likelihood that the merger will be completed; and



•

the ability of the combined company to realize certain operating efficiencies as a result of the merger.

    Cogent also identified and considered a number of potentially negative factors in its deliberations concerning the merger, including:

•

the risk that, despite Cogent and Allied Riser's efforts after the merger, the combined company may lose key personnel;



•

the risk that Cogent and Allied Riser's customers and suppliers might cease doing business with the combined company;



•

the risk of potential adverse effects of one-time and/or recurring charges expected to be incurred in connection with the costs of the merger and the subsequent integration of the companies;



•

the risk that the potential benefits of the merger might not be fully realized;



•

the effect on the interests of Cogent stockholders associated with becoming a public company and the difficulties for Cogent in establishing and maintaining quotation or listing on the Nasdaq National Market or on a national securities exchange; and



•

the risk of litigation by stockholders and noteholders of Allied Riser.

    Cogent believes that these and other risks can be avoided or mitigated, and that, overall, they are outweighed by the potential benefit of the merger.

    The foregoing discussion of the information and factors considered by the Cogent board of directors is not exhaustive but does include material factors considered by the Cogent board of directors. The Cogent board of directors did not quantify or assign any relative or specific weights to the various factors that it considered. Rather, the Cogent board of directors based its recommendation on the totality of the information presented to and considered by it. In addition, individual members of the Cogent board of directors may have given differing weights to different factors.

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Regulatory Approvals Required for the Merger

    Cogent and Allied Riser have agreed to use their reasonable best efforts to obtain all regulatory approvals required in order to consummate the merger. Cogent and Allied Riser have either filed, or intend to file promptly after the date of this document, applications and notifications to obtain the required regulatory approvals, including approval from the Federal Communications Commission and various state regulatory authorities. Cogent and Allied Riser cannot provide any assurances that the required regulatory approvals will be obtained and, if obtained, as to the date of any of these approvals or the absence of any litigation challenging them or the merger. We can also not assure you that regulatory authorities will not, as a condition to granting their approval, require us to take actions that could adversely affect the expected value of the combined company following the merger.

    Allied Riser has been granted authorizations to provide telecommunications services by federal and state regulatory agencies, but does not believe these authorizations are required to conduct its business. Allied Riser will seek the approval of the relevant regulatory agencies prior to consummating the merger to the extent required by the merger agreement and may otherwise seek approval of the relevant regulatory agencies prior to consummating the merger to the extent necessary to maintain these authorizations.

MATERIAL TERMS OF THE MERGER AGREEMENT

General

    The following summary of the merger agreement is qualified by reference to the complete text of the merger agreement and amendment no. 1, each of which is incorporated by reference and attached to this document as Appendix A and Appendix B, respectively, to this document. We encourage you to read the merger agreement because it is the legal document that governs the merger. The parties to the merger agreement are Cogent, Allied Riser, and the merger subsidiary.

    Under the merger agreement, the merger subsidiary will merge into Allied Riser. As a consequence of the merger, the separate corporate existence of the merger subsidiary will cease and Allied Riser will continue as the surviving corporation and a wholly owned subsidiary of Cogent.

Closing; Effective Time

    We will close the merger at 10:00 a.m., Eastern Time, no later than the second business day after the conditions set forth in the merger agreement have been satisfied or waived, unless we agree to another date and time.

    On the date of closing, we will file a certificate of merger and other appropriate documents with the Secretary of State of Delaware in accordance with the relevant provisions of Delaware law. The merger will become effective when the certificate of merger is filed with the Secretary of State of Delaware, or at such later time as we specify in the certificate of merger.

Consideration to be Received in the Merger

    At the effective time of the merger, without any further action, each outstanding share of Allied Riser common stock, other than those shares held in the treasury of Allied Riser, or held by Cogent or its subsidiaries, will be converted into the right to receive a number of newly and validly issued, fully paid, and non-assessable shares of Cogent common stock.

•

If the merger is completed and Cogent does not issue any of its common stock in other transactions between now and the date the merger is completed, Allied Riser stockholders will receive 0.0321780 shares of Cogent common stock for each share of Allied Riser common stock that they own. If the merger is completed and, between now and the date the merger is completed, Cogent issues additional shares of its common stock in other transactions, Allied Riser stockholders will receive a lesser number of shares, but no fewer than 0.0317560 shares of Cogent common stock for each share of Allied Riser. Cogent will not issue fractional shares of its common stock. Instead, any otherwise fractional share will be rounded up to a whole share. The number of shares Allied Riser stockholders will receive reflect a one for ten reverse stock split of Cogent that is expected to occur immediately prior to the consummation of the merger.



•

Under the merger agreement, Cogent is prohibited from issuing additional shares of capital stock, including common stock, unless the stock issued meets the following criteria, as set forth in Exhibit C to the merger agreement:



•

Cogent must receive at least $1.2467 per share for additional shares issued, calculated (prior to any reverse stock split) on a fully diluted, common-equivalent shares basis;



•

the terms of additional shares issued must be no less favorable to Allied Riser and its stockholders than the terms of the Series C preferred stock, which terms are described in Annex B to the amendment to the merger agreement; and



•

the additional shares issued may not result in the number of fully diluted, common-equivalent shares of Cogent exceeding 23,797,924.

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    Any share of Allied Riser common stock held by Allied Riser as treasury stock, or by Cogent, will be automatically canceled and retired in the merger and will cease to exist. We will not exchange those shares for any securities of Cogent or other consideration.

    At the effective time of the merger, each outstanding share of the merger subsidiary will be automatically converted into and become one newly and validly issued, fully paid, and non-assessable share of common stock of Allied Riser, and these shares will, collectively, represent all of the issued and outstanding capital stock of Allied Riser.

    No fractional shares will be issued in the merger. In lieu of the issuance of any fractional share of Cogent common stock, each holder who would otherwise be entitled to receive a fractional share will receive an additional fraction of a share of Cogent common stock to create a whole share of Cogent common stock.

Procedures for Exchange of Certificates

Exchange of Certificates

    Promptly after the effective time of the merger, the exchange agent for the merger will send you a letter of transmittal. The letter of transmittal will contain instructions with respect to the surrender of your Allied Riser stock certificates. You should not return stock certificates with the proxy card enclosed with this proxy statement/prospectus.

    Commencing immediately after the effective time of the merger, if you surrender your stock certificates representing Allied Riser shares in accordance with the instructions in the letter of transmittal, you will be entitled to receive stock certificates representing the shares of Cogent common stock into which those Allied Riser shares are converted in the merger.

    After the merger, each certificate that previously represented shares of Allied Riser stock will represent only the right to receive the shares of Cogent common stock into which the shares of Allied Riser stock were converted in the merger.

    We will close Allied Riser's transfer books at the effective time of the merger and no further transfers of shares will be recorded on the transfer books. If a transfer of ownership of Allied Riser stock that is not registered in the records of Allied Riser's transfer agent has occurred, then, so long as the Allied Riser stock certificates are accompanied by all documents required to evidence and effect the transfer, as set forth in the transmittal letter and accompanying instructions, and by evidence of payment of any applicable stock transfer taxes, a certificate representing the proper number of shares of Cogent common stock will be issued to a person other than the person in whose name the certificate so surrendered is registered, together with payment of dividends or distributions, if any.

Dividends and Distributions

    You will not be paid any dividends or distributions on Cogent common stock into which your Allied Riser shares have been converted with a record date after the merger until you surrender your Allied Riser certificates to the exchange agent. When you surrender those certificates, any unpaid dividends payable as described below will be paid without interest. We do not anticipate paying any dividends in the immediate future.

Lost Certificates

    If any Allied Riser common stock certificate is lost, stolen, or destroyed, the holder must make an affidavit of that fact to the exchange agent in order to receive Cogent common stock in respect of the lost, stolen, or destroyed certificates, and any unpaid dividends and distributions in respect thereof. In

46

addition, we may require the holder to post a bond as indemnity against any claim that may be made against it with respect to the lost, stolen, or destroyed certificates.

Withholding

    Either Cogent or the exchange agent, on behalf of the surviving corporation, is entitled to deduct and withhold from the consideration otherwise payable to any holder of shares of Allied Riser common stock any amounts it is required to deduct and withhold under applicable law with respect to the making of such payment. Any amounts withheld will be treated for all purposes of the merger agreement as having been paid to the former holder of Allied Riser common stock.

Termination of Exchange Fund; No Liability

    On the first anniversary of the effective time of the merger, the exchange agent will, upon Cogent's request, deliver to Cogent any portion of the shares of Cogent common stock (or dividends or distributions thereon) that remain undistributed to the former holders of Allied Riser common stock. After that date, any former holders of Allied Riser common stock who have not already exchanged their certificates for shares of Cogent common stock will have no recourse against the exchange agent and will look only to Cogent for the shares of Cogent common stock, and dividends and distributions thereon, to which they are entitled. In addition, neither Cogent nor the surviving corporation will be liable to any former holders of shares of Allied Riser common stock for shares of Cogent common stock delivered to a public official pursuant to any applicable abandoned property, escheat, or similar law. Immediately prior to the third anniversary of the effective time of the merger—or any earlier date that shares of Cogent common stock exchangeable for former shares of Allied Riser common stock (or any dividends or distributions thereon) would otherwise escheat to or become the property of a governmental entity—any such shares of Cogent common stock (and all dividends and distributions thereon) will, to the extent permitted by applicable law, become the property of the surviving corporation.

Stock Options; Restricted Stock; and Warrants

Stock Options

    At the effective time of the merger, each outstanding option to purchase Allied Riser common stock will remain outstanding and be assumed by Cogent. Each option to purchase Allied Riser common stock will be converted into an option to purchase, on the same terms and conditions as were applicable under such option immediately prior to the merger, the number of shares of Cogent common stock (rounded to the nearest whole number) equal to the product of:

•

the number of shares of Allied Riser common stock that could have been obtained prior to the merger upon exercise of such option and



•

the number of shares of Cogent common stock into which each share of Allied Riser common stock is convertible in the merger;

at an exercise price per share of Cogent common stock (rounded to the nearest whole cent) equal to:

•

the exercise price per share of Allied Riser common stock for such option immediately prior to the merger, divided by



•

the number of shares of Cogent common stock into which each share of Allied Riser common stock is convertible in the merger.

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Restricted Stock

    At the effective time of the merger each share of Allied Riser common stock subject to a repurchase option, risk of forfeiture, or other condition or restriction will be converted into the same number of shares of Cogent common stock into which shares of unrestricted Allied Riser common stock convert. All shares of Cogent common stock issued in exchange for shares of restricted Allied Riser common stock will retain any such condition or restriction, except to the extent provided otherwise in any agreement between Allied Riser and any holder of shares of restricted Allied Riser common stock.

Warrants

    At the effective time of the merger, each warrant to purchase Allied Riser common stock will automatically be converted into a warrant to purchase, on the same terms and conditions as were applicable under such warrant immediately prior to the merger, the number of shares of Cogent common stock (rounded to the nearest whole number) equal to the product of:

•

the number of shares of Allied Riser common stock that could have been obtained prior to the merger upon exercise of such warrant; and



•

the number of shares of Cogent common stock into which each share of Allied Riser common stock is convertible in the merger;

at an exercise price per share of Cogent common stock (rounded to the nearest whole number) equal to:

•

the exercise price per share of Allied Riser common stock for such warrant immediately prior to the merger; divided by



•

the number of shares of Cogent common stock into which each share of Allied Riser common stock is convertible in the merger.

Representations and Warranties

    In the merger agreement, Allied Riser represents and warrants to Cogent, and each of Cogent and the merger subsidiary represent and warrant to Allied Riser, that:

•

it is duly organized, validly existing, and in good standing as a Delaware corporation, and its capital stock is as stated in the merger agreement;



•

it is duly qualified or licensed to do business and is in good standing in each jurisdiction where such qualification or license is required, except as would not have a material adverse affect on it;



•

it has properly authorized, executed, and delivered the merger agreement;



•

the merger agreement is enforceable against it, and required material consents, approvals, orders, and authorizations of governmental authorities and third parties relating to the merger agreement have been obtained except as contemplated by the merger agreement;



•

it will not contravene in a material manner other agreements as a result of the merger agreement;



•

the information it supplied for inclusion in this proxy statement/prospectus is accurate; and



•

the votes of its stockholders that are required in connection with the merger are as stated in the merger agreement.

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    In addition, Allied Riser represents and warrants to Cogent that:

•

documents it filed with the SEC do not contain untrue statements of material fact or omit material facts;



•

financial statements it filed with the SEC fairly present in all material respects its financial condition;



•

except as disclosed in its filings with the SEC or as permitted by, or as disclosed in, the merger agreement, no material changes or events have occurred with respect to Allied Riser or its subsidiaries since June 30, 2001;



•

except as disclosed, there is no material suit or action filed or threatened against Allied Riser or its subsidiaries;



•

Allied Riser and its subsidiaries have complied with all applicable laws and permits, except as would not cause a material adverse effect on it; and



•

no broker or financial advisor, other than Houlihan Lokey, is entitled to any fee or commission in connection with the merger based on arrangements made by Allied Riser or its subsidiaries.

    In addition, Cogent and the merger subsidiary represent and warrant to Allied Riser that:

•

annual financial statements for the years ended December 31, 2000 and 1999, and financial statements for the six months ended June 30, 2001, fairly present in all material respects the financial condition of Cogent and its subsidiaries;



•

except as permitted by, or as disclosed in, the merger agreement, no material changes or events have occurred with respect to Cogent or its subsidiaries since June 30, 2001;



•

except as disclosed, there is no material suit or action filed or threatened against Cogent or its subsidiaries;



•

Cogent and its subsidiaries have complied with all applicable laws and permits, except as would not cause a material adverse effect on it;



•

Cogent's employee benefit matters, intellectual property matters, environmental matters, tax matters, and insurance matters all are as stated in the merger agreement;



•

Cogent and its subsidiaries are not in breach of their material contracts and debt instruments, except as disclosed;



•

except as disclosed, neither Cogent nor any of its subsidiaries have engaged in any transaction with affiliates described in the merger agreement;



•

no broker or financial advisor is entitled to any fee or commission in connection with the merger based on arrangements made by Cogent or its subsidiaries; and



•

Cogent does not intend to consummate a Rule 13e-3 transaction or otherwise acquire, directly or indirectly, more than 80% of the shares of Cogent common stock issued in the merger for at least six months after consummation of the merger.

    The representations and warranties are of no further force or effect after the effective time of the merger.

Conduct of the Business Prior to the Merger

    Each of Cogent and Allied Riser has agreed to operate its business in the ordinary course of business prior to the merger, except as disclosed, and except as consented to in writing by the other

49

party. Neither party can unreasonably withhold or delay a requested consent to an exception to this covenant.

    Cogent has also agreed that:

•

it and its subsidiaries will not take any actions that delay the filing of or require any amendment or supplement to Cogent's Form S-4 registration statement, or recirculation of this proxy statement/prospectus;



•

the Cogent board of directors will not withdraw or modify, or propose publicly to withdraw or modify, in a manner adverse to Allied Riser, its approval or recommendation of the merger; and



•

it and its subsidiaries will not acquire or agree to acquire by merging or consolidating with, or by purchasing a substantial portion of the assets of, or by any other manner, any material business or any person, other than purchases of supplies in the ordinary course of business; provided, however, that it is not prohibited from completing certain specified intercompany transactions.

    Allied Riser has also agreed that it and each of its subsidiaries will not do any of the following:

•

incur any expenses or make any payments in excess of, or take any action materially inconsistent with, the statement of authorized cash expenditures to which it has agreed with Cogent;



•

declare, set aside, or pay dividends on, or make any other distributions with respect to, any of its capital stock, except for dividends by a wholly owned subsidiary of Allied Riser to its parent and dividends by its other subsidiaries of which it receives its proportionate share;



•

split, combine, or reclassify any of its capital stock or issue or authorize the issuance of any other securities in substitution for its capital stock;



•

purchase or redeem any shares of its capital stock or other securities thereof;



•

issue or sell, or grant options to acquire, any shares of its capital stock or any securities convertible into, or exercisable for, such capital stock, except for the issuance of shares of Allied Riser common stock upon the exercise of currently outstanding options or warrants or the conversion of Allied Riser's convertible notes, in each case in accordance with the governing plan or agreement, as the case may be;



•

amend its certificate of incorporation or bylaws or other comparable organizational documents;



•

acquire, other than for cash consistent with the authorized cash expenditures, by merger or acquisition of stock or assets, any business or entity, except for supplies in the ordinary course of business consistent with past practice;



•

incur any material debt or guaranty any such indebtedness for another person, issue or sell any debt securities or warrants or other rights to acquire any debt securities, or enter into any arrangement having a similar economic effect, except for intercompany debt and short-term borrowings incurred in the ordinary course of business consistent with past practice;



•

make any material loans, advances, or capital contributions to, or investments in, any other person;



•

pay, discharge, settle, or satisfy, other than for cash consistent with the authorized cash expenditures, any claims, liabilities, obligations, or litigation, other than payment, discharge, settlement, or satisfaction, in the ordinary course of business consistent with past practice, or in accordance with its terms, of any liability that is recognized or disclosed in its most recent consolidated financial statements filed with the SEC or that was incurred since the date of those statements for an amount not to exceed the specific reserve for such liability set forth in those statements, except that Allied Riser is permitted to settle its obligations to Cisco System Capital

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Corporation and terminate certain agreements, contracts and leases in accordance with the terms of the merger agreement;

•

waive or modify any standstill or similar agreement to which it is a party;



•

except as required by law or contemplated by the merger agreement:



•

enter into, adopt, amend in any material respect, or terminate any benefit plan or benefit arrangement or



•

materially change any assumption used to calculate funding obligations with respect to any pension plan, or change the manner in which contributions to any pension plan are made or the basis on which such contributions are determined;

•

except as disclosed, enter into or terminate any contract or commitment, or violate, amend, or otherwise modify or waive any of the terms of any of its contracts;



•

materially reduce the amount of any material insurance coverage under existing insurance policies;



•

make any changes in accounting methods, principles, or practices unless required by changes in the Generally Accepted Accounting Principles, Regulation S-X promulgated by the SEC, or applicable statutory accounting principles;



•

agree to take any of the foregoing actions; or



•

make any materially adverse tax election.

No Solicitation

    The merger agreement provides that, except as described below, Allied Riser may not, directly or indirectly:

•

solicit, initiate, encourage (including by furnishing information), or take any other action designed to facilitate, any takeover proposal or related inquires or



•

participate in any discussion or negotiation regarding any takeover proposal.

    Allied Riser must immediately notify Cogent orally and in writing of any takeover proposal or any related inquiry. Allied Riser's notice must identify the person making the proposal or inquiry and describe the material terms and conditions of the proposal or inquiry. Allied Riser must keep Cogent informed of the status and material details of—including amendments and proposed amendments to—any proposal or inquiry.

    If Allied Riser receives an unsolicited superior proposal and the Allied Riser board of directors determines, upon consultation with outside legal counsel, that the failure to negotiate in response to the superior proposal would result in a breach of their fiduciary duties, Allied Riser may, after giving Cogent the required notice:

•

furnish information to any person making a superior proposal in accordance with a customary confidentiality agreement and



•

negotiate regarding the superior proposal.

    A "takeover proposal" is broadly defined to include any inquiry, proposal, or offer from any third person relating to:

•

any direct or indirect acquisition of a business or asset that constitutes 15% or more of Allied Riser's consolidated net revenues, net income, or assets

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•

any direct or indirect acquisition of 15% or more of any class of Allied Riser's or any of its subsidiaries' equity securities;



•

any tender offer or exchange offer that, if completed, would result in any person beneficially owning 15% or more of any class of Allied Riser's or any of its subsidiaries' equity securities; or



•

any merger, consolidation, business combination, recapitalization, liquidation, dissolution, or similar transaction involving Allied Riser or any of its subsidiaries.

    A "superior proposal" is defined as any offer to acquire, directly or indirectly, more than 50% of the combined voting power of the then-outstanding shares of Allied Riser's common stock, or all or substantially all of its assets:

•

that in the good faith judgment of the Allied Riser board—after consultation with its independent financial advisors and legal counsel—would, taking into account all terms and conditions of the proposal, be more favorable to Allied Riser's stockholders than the merger and



•

for which financing, to the extent required, is then committed or which, in the good faith judgment of the Allied Riser board, is reasonably capable of being obtained by the offeror.

    Except as set forth below, the Allied Riser board may not:

•

withdraw or modify, or propose publicly to withdraw or modify, in a manner adverse to Cogent, its approval or recommendation of the merger;



•

approve, recommend, or remain neutral to, or propose publicly to approve, recommend, or remain neutral to, any takeover proposal; or



•

cause Allied Riser to enter into any letter of intent, agreement in principle, acquisition agreement, or other similar agreement related to any takeover proposal.

    Regardless of these restrictions, the Allied Riser board may terminate the merger agreement in response to a superior proposal:

•

which was not solicited by Allied Riser and which otherwise did not result from Allied Riser's breach of its related obligations and



•

after the second business day following Cogent's receipt of notice from Allied Riser advising Cogent that Allied Riser is prepared to accept a superior proposal, specifying the material terms and conditions of the superior proposal and identifying the person making the superior proposal.

    In addition, regardless of these restrictions, Allied Riser may participate in discussions and negotiations with its noteholders, but it may not enter any agreement with, or make any payment to, its noteholders without Cogent's prior written consent.

Additional Agreements

Employee Benefits

    After the merger, Cogent will provide for the continuation of healthcare benefits for those employees and former employees identified in a schedule to the merger agreement. These healthcare benefits will continue from each identified employee's termination date for the number of weeks specified in the relevant schedule. These healthcare benefits will be substantially similar to the benefits of each such employee prior to the effective time of the merger.

    Prior to the effective time of the merger, Allied Riser will fully vest all remaining active participants in its 401(k) plan, and terminate this plan.

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Insurance and Indemnification

    After the merger, the surviving corporation will indemnify each person who is, or has been, a director or officer of Allied Riser with respect to all acts or omissions taken by them before the merger to the extent each such person, prior to the merger, was entitled to the benefit of indemnification agreements or the provisions of Allied Riser's certificate of incorporation and bylaws relating to indemnification.

    For six years after the merger, the surviving corporation will maintain in effect (1) Allied Riser's and its subsidiaries' current directors' and officers' liability insurance covering acts or omissions occurring before the merger, and covering each person currently covered by this insurance, and (2) Allied Riser's and its subsidiaries' current fiduciary liability insurance covering acts or omissions occurring before the merger for employees who served as fiduciaries with respect to any of Allied Riser's employee benefits plans, in each case on terms with respect to coverage and amounts no less favorable than those in effect on August 28, 2001. The surviving corporation will not be required to pay, in total, an annual premium for the insurance described in this paragraph in excess of 200% of the current total annual premium Allied Riser pays for its existing coverage prior to the merger. If the annual premiums exceed that amount, the surviving corporation will be obligated to obtain a policy with coverage that may be obtained for that amount.

Fees and Expenses

    Whether or not the merger is completed, we will share the expense of this proxy statement/prospectus and the SEC registration statement of which it is a part, and we will each pay all of our own other costs and expenses incurred in connection with the merger and the merger agreement, subject to the expense reimbursement and termination fee provisions described under "—Termination Fee."

Listing or Nasdaq Quotation

    Cogent and Allied Riser will use their reasonable best efforts to cause the shares of Cogent common stock issuable in the merger to be approved for quotation on the Nasdaq National Market or listing on a national securities exchange.

Affiliates

    Allied Riser has agreed to deliver to Cogent a letter identifying all persons who may be, at the time of the special meeting, "affiliates" for purposes of Rule 145 under the Securities Act of 1933, as amended, or the Securities Act, and to use its reasonable best efforts to cause each of those affiliates to enter into a written agreement not to offer, sell, or otherwise dispose of any of the shares of Cogent common stock issued to them in the merger in violation of the Securities Act or the rules promulgated thereunder.

Director Designation

    Cogent will appoint to its board of directors a person designated by Allied Riser, who must be acceptable to three of the larger stockholders of Allied Riser, immediately prior to the effective time of the merger.

Going Private Transaction

    Cogent will not, for six months after the consummation of the merger, consummate a Rule 13e-3 transaction or acquire, directly or indirectly, more than 80% of the shares of Cogent common stock issued in the merger.

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Reasonable Best Efforts

    The merger agreement also contains additional covenants, including a covenant to use reasonable best efforts to take all actions, and to do all things, necessary, proper, or advisable to complete the merger, and the other transactions contemplated by the merger agreement, as promptly as practicable, including, among other things:

•

causing certain Allied Riser stockholders to enter into voting agreements with Cogent;



•

obtaining all necessary waivers, consents, or approvals by governmental entities;



•

obtaining all necessary waivers, consents, or approvals from third parties;



•

defending any lawsuits or legal proceedings that challenge the merger agreement; and



•

executing and delivering any additional instruments.

Conditions to Completion of the Merger

    Each party's obligation to complete the merger is subject to satisfaction or waiver of the following conditions:

•

no court issues an order and no law is enacted which would make the completion of the merger illegal or otherwise prohibited;



•

the SEC declares effective Cogent's Form S-4 registration statement, of which this proxy statement/prospectus is a part;



•

the Nasdaq National Market or a national securities exchange, has approved for quotation or listing the shares of Cogent common stock to be issued in the merger, subject to official notice of issuance;



•

the representations and warranties made by the other party are true and correct in all material respects (except for representations and warranties qualified by materiality, which must be true and correct) as of the closing date—except to the extent expressly made as of an earlier date, in which case as of that date;



•

the other party has performed in all material respects all agreements and covenants that it must perform under the merger agreement before the closing date; and



•

each has received an opinion from its legal counsel that (1) the merger will constitute a reorganization within the meaning of Section 368(a) of the Internal Revenue Code and (2) each party will constitute a "party to a reorganization" within the meaning of Section 368(b) of the Internal Revenue Code.

    Cogent's obligation to complete the merger is subject to the further conditions that:

•

it has received any required approval of its stockholders;



•

Allied Riser has obtained material consents required in connection with the merger; and



•

except as described in a schedule to the merger agreement, no litigation by or on behalf of holders of Allied Riser's securities that is reasonably likely to have a material adverse effect on the surviving corporation shall be pending or threatened against Allied Riser, its subsidiaries, or their respective officers or directors.

    Allied Riser's obligation to complete the merger is subject to the further conditions that:

•

it has received the required approval of its stockholders;



•

Cogent has obtained material consents required in connection with the merger; and



•

Cogent has issued at least $62 million of Series C preferred stock for cash on substantially the terms set forth in the merger agreement.

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    Cogent and Allied Riser currently believe that it is likely that all of the conditions to the merger will be fulfilled. In the unlikely event that a condition is not fulfilled, the parties may, but would not be required to, waive the condition and complete the merger. If the waiver were to result in a material change in the terms of the merger, then Allied Riser would resolicit the votes of its stockholders to approve the merger.

Termination of the Merger Agreement

    The merger agreement may be terminated, whether before or after receiving any stockholder approval:

•

by mutual written consent of Cogent and Allied Riser;



•

by either Cogent or Allied Riser:



•

if we do not complete the merger on or before December 7, 2001 or, if the SEC informs Cogent or Allied Riser that the SEC will review this proxy statement/prospectus, the earlier of January 31, 2002 and the 25 ^th day after the effective date of this proxy statement/prospectus, except that a party may not terminate the agreement if its failure to fulfill its obligations results in the merger not being completed by that date;



•

if the Allied Riser stockholders do not adopt the merger agreement;



•

if Cogent does not obtain any authorization of stockholders required to consummate the transactions contemplated by the merger agreement;



•

if a law makes the merger illegal or a court or other government authority issues a final non-appealable ruling that permanently prohibits the completion of the merger, unless the party seeking to terminate the merger agreement has not used reasonable best efforts to prevent such law or ruling from becoming final and non-appealable;



•

if the other party has breached any of its representations, warranties, covenants, or agreements contained in the merger agreement, and the breach would result in the failure to satisfy one or more of the conditions to the merger, and the breach is incapable of being cured or, if capable of being cured, has not been cured within 30 days after written notice; or



•

if Cogent did not issue at least $62 million of its Series C preferred stock for cash on substantially the terms set forth in the merger agreement by October 17, 2001.

•

by Cogent, if Allied Riser or its subsidiaries or any of their respective directors or officers:



•

participates in discussions or negotiations in violation of its obligations not to solicit or encourage takeover proposals;



•

withdraws or modifies, or proposes publicly to withdraw or modify, in a manner adverse to Cogent, its approval or recommendation of the merger;



•

approves, recommends, or remains neutral to, or proposes publicly to approve, recommend, or remain neutral to, any takeover proposal; or



•

causes Allied Riser to enter into any letter of intent, agreement in principle, acquisition agreement, or other similar agreement related to any takeover proposal; and

•

by Allied Riser, if it has received a superior proposal and has complied with its obligations described in "—No Solicitation," and has paid the termination fee described immediately below in "—Termination Fee."

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Termination Fee

    Allied Riser must pay Cogent a $5,000,000 termination fee if:

•

Cogent terminates the merger agreement due to the fact that Allied Riser's breach of any of its covenants or agreements contained in the merger agreement would result in the failure to satisfy one or more of the conditions to the merger, and the breach is incapable of being cured or, if capable of being cured, has not been cured within 30 days after written notice;



•

Cogent terminates the merger agreement after Allied Riser or its subsidiaries or any of their respective directors or officers:



•

participates in discussions or negotiations in violation of its obligations not to solicit or encourage takeover proposals;



•

withdraws or modifies, or proposes publicly to withdraw or modify, in a manner adverse to Cogent, its approval or recommendation of the merger;



•

approves, recommends, or remains neutral to, or proposes publicly to approve, recommend, or remain neutral to, any takeover proposal; or



•

causes Allied Riser to enter into any letter of intent, agreement in principle, acquisition agreement, or other similar agreement related to any takeover proposal.

•

the merger has not been completed due to Allied Riser's failure to obtain a material consent it was required to obtain, and Cogent terminates the merger agreement because the merger has not been completed by December 7, 2001 or, if the SEC informs Cogent or Allied Riser that the SEC will review this proxy statement/prospectus, the earlier of January 31, 2002 and the 25 ^th day after the effective date of this proxy statement/prospectus;



•

Cogent terminates the merger agreement because Allied Riser's stockholders have not approved the merger at their stockholder meeting or any adjournment thereof; or



•

Allied Riser terminates the merger agreement in response to a superior proposal.

    Cogent must pay Allied Riser a $5,000,000 termination fee if:

•

Allied Riser terminates the merger agreement due to the fact that Cogent's breach of any of its covenants or agreements contained in the merger agreement would result in the failure to satisfy one or more of the conditions to the merger, and the breach is incapable of being cured or, if capable of being cured, has not been cured within 30 days after written notice;



•

the merger has not been completed due to Cogent's failure to obtain a material consent it was required to obtain, and Allied Riser terminates the merger agreement because the merger has not been completed by December 7, 2001 or, if the SEC informs Cogent or Allied Riser that the SEC will review this proxy statement/prospectus, the earlier of January 31, 2002 and the 25 ^th day after the effective date of this proxy statement/prospectus;



•

Allied Riser terminates the merger agreement because any required approval of Cogent's stockholders in connection with this transaction has not been obtained; or



•

Allied Riser terminates the merger agreement due to Cogent's failure to satisfy the condition that it raise at least $30,000,000 in a private placement of Series C preferred stock.

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Amendments, Extensions and Waivers

Amendments

    The merger agreement may be amended by the parties at any time prior to the effective time of the merger. However, after Allied Riser stockholders approve the merger agreement and the merger or Cogent stockholders approve the merger agreement and the merger, no amendment may be made that requires further approval by stockholders under applicable law or the rules of any relevant stock exchange, without obtaining the required approval. All amendments to the merger agreement must be in writing and signed by each party.

Extensions and Waivers

    At any time prior to the effective time of the merger, any party to the merger agreement may:

•

extend the time for the performance of any of the obligations or other acts of the other parties to the merger agreement;



•

waive any inaccuracies in the representations and warranties of the other parties contained in the merger agreement; and



•

except as required by law, waive compliance by the other party with any of the agreements or conditions contained in the merger agreement.

    All extensions and waivers must be in writing and signed by the party against whom the waiver is to be effective.

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OTHER AGREEMENTS

Voting Agreements

    Prior to the consummation date of the merger, certain holders of Allied Riser common stock who own, in the aggregate, approximately 26.3% of Allied Riser's common stock, specifically Norwest Venture Partners VII, LP, Telecom Partners II, LP, and Crescendo World Fund, LLC, executed and delivered agreements that each holder agrees to:

•

attend Allied Riser's stockholder meeting in person or by proxy; and



•

vote all Allied Riser shares it owns or has the right to vote in favor of adoption of the merger agreement and approval of the merger, and any other matters necessary to complete the merger.

    In addition, until the termination of the merger agreement, its subsequent amendment in a material manner, or the consummation of the merger, each such holder of Allied Riser shares has agreed not to sell or pledge any such shares or voting interests therein.

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MANAGEMENT OF COGENT FOLLOWING THE MERGER AND OTHER INFORMATION

    Following the merger, the directors, executive officers, and other key employees of Cogent and their ages as of October 10, 2001 will be as follows:

    We have listed below biographical information for each person who is expected to be a director, executive officer, or key employee following the merger.

     David Schaeffer founded Cogent in August 1999 and is the Chairman and Chief Executive Officer. Prior to founding Cogent, Mr. Schaeffer was the founder of Pathnet, Inc., a broadband telecommunications provider, where he served as Chief Executive Officer from 1995 until 1997 and as Chairman from 1997 until 1999. On April 2, 2001, Pathnet, Inc. filed for bankruptcy under Chapter 11 of the United States Bankruptcy Code.

     William Currer joined Cogent in June 2000 as President and Chief Operating Officer. From 1991 to 1999, Mr. Currer served as Group President, Communication Systems for Andrew Corp., a wireless communications infrastructure technology company.

     H. Helen Lee , the Company's Chief Financial Officer and a director, joined Cogent in November 2000. Prior to joining Cogent, Ms. Lee worked in the LBO group of the Audax Group, a private equity firm in Boston, MA in 2000. From 1997 to 1998 Ms. Lee worked at Pathnet Inc., directing financing and corporate development activities. From 1995 to 1997, Ms. Lee worked in the Telecom M&A/Advisory Group at J.P. Morgan, where she participated in merger and acquisition transactions and advised on equity and high-yield offerings.

     Robert Beury joined Cogent in September 2000 as General Counsel. Prior to joining Cogent, Mr. Beury served as Deputy General Counsel of Iridium LLC from 1994 to 2000. From 1987 to 1994 Mr. Beury was General Counsel of Virginia's Center for Innovative Technology, a non-profit corporation set up to develop the high tech industry in Virginia.

     Barry Morris joined Cogent in April 2000 as Vice President of Sales. Mr. Morris has over 19 years of experience in the sale and complex integration of large data communication networks. From 1997 to 2000, Mr. Morris served as Senior Director of Sales for Nortel Networks where he managed a staff of pre- and post-sales engineers, account executives, and regional managers, and performed marketing and sales consulting duties. Preceding its acquisition by Nortel, Mr. Morris served as the Vice President of Sales for Bay Networks from 1994 to 1997 and as District Sales Manager for Synoptics prior to its acquisition by Bay Networks.

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     Scott Stewart joined Cogent in May 2000 as the Vice President of Real Estate. He is responsible for leading a team of professionals to build Cogent's nationwide network of multi-tenant office buildings. From 1999 to 2000, Mr. Stewart was a Vice President at Carlyle Realty, a division of The Carlyle Group, a multi-national private equity group based in Washington, D.C. From 1995 to 1999, Mr. Stewart directed the east-coast development program for Homestead Village, an extended stay hotel company and subsidiary of Security Capital Group. While there, Mr. Stewart was responsible for leading a team of 25 development professionals in the construction of 72 hotels in 18 cities. From 1993 to 1995, Mr. Stewart was the President and Founder of Potomac Land and Development Company, a Washington, D.C. metropolitan area real estate investment and consulting firm. From 1991 to 1993, Mr. Stewart was a Vice President and managed the Real Estate Owned properties of a Virginia based bank. Prior to then, Mr. Stewart served as a residential community developer in suburban Washington, D.C.

     Bradley Kummer joined Cogent in February 2000 as Vice President and Chief Technology Officer. Mr. Kummer spent the 25 years prior to joining Cogent at Lucent Technologies (formerly Bell Laboratories), where he served in a variety of research and development and business development roles relating to optical fibers and systems. In his most recent work at Lucent, he was responsible for optical fiber systems engineering for long haul and metropolitan dense wavelength division multiplexing systems.

     Neale D'Rozario joined Cogent in July 2000 and currently serves as Chief Information Officer. He is responsible for the Network Operations Center and Corporate Technology. From 1996 to 2000, Mr. D'Rozario was the Chief Information Officer for SunTrust Bank's investment banking division. While at SunTrust, Mr. D'Rozario was responsible for technology supporting equity and debt capital raising and trading activities. From 1991 to 1996, D'Rozario was the Global Managing Director of Technology for Barclays Bank, BZW Debt Capital Markets. There he was responsible software development, third party package integration network infrastructure. From 1986 to 1991 Mr. D'Rozario served as the Information Systems Manager at Salomon Brothers, Inc.

     Timothy O'Neill joined Cogent in January 2001 as the Vice President of Engineering Construction. He is responsible for the network build-out and provisioning. From 1999 to 2001, Mr. O'Neill was employed at @Link Networks where he served as Chief Network Officer. While at @Link, Mr. O'Neill was responsible for engineering, implementing, and operating an integrated communications network. From 1998 to 1999, Mr. O'Neill was the Vice President of National Operations for NEXTLINK. His responsibilities included the NOC, network assurance, central office construction, provisioning, and engineering. Mr. O'Neill has also held senior management positions with Time Warner Communications and Internet Communications from 1994 to 1998.

     Mark Schleifer joined Cogent in October, 2000 and currently serves as Vice President of IP Engineering. From 1994 to 2000, Mr. Schleifer served as Senior Director, Network Engineering at DIGEX/Intermedia, a provider of high-end managed Web and application hosting services. At DIGEX/Intermedia, Mr. Schleifer managed the Network Engineering group, Capacity Planning group, and Research and Development group. He was responsible for all technical aspects of customer turn up, network troubleshooting, field installations, and new equipment testing for the leased line business. Mr. Schleifer also coordinated peering and backbone circuit deployment to maintain network throughput and availability.

     Thaddeus Weed joined Cogent in February 2000 as Controller. From 1997 to 1999, Mr. Weed served as Senior Vice President of Finance and Treasurer at Transaction Network Services where Mr. Weed undertook a broad range of financial management responsibilities. These responsibilities included financial planning, forecasting, budgeting, financial modeling, acquisition, and international expansion strategies and pro-forma analyses. In 1999 he negotiated and completed the sale of Transaction Network Services to PSINet. From 1987 to 1997, Mr. Weed was employed at Arthur Andersen where

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he served as Senior Audit Manager, consulting on due diligence and operational improvement issues and performing audits of public and private entities.

     Edward Glassmeyer has served on Cogent's board of directors since 2000. Mr. Glassmeyer was with Citicorp Venture Capital from 1968 to 1970, and The Sprout Capital Group where he was Managing Partner from 1971 to 1974. In 1973, he became a founding director of the National Venture Capital Association (NVCA). In 1978, he co-founded Oak Investment Partners, a venture capital firm. Since July 1996, he has been an Overseer of The Tuck School at Dartmouth College. Mr. Glassmeyer serves on the board of directors of a number of Oak portfolio companies supplying network equipment and services, including Apogee Networks, Movaz, Telica, and Tellium.

     Erel Margalit has served on Cogent's board of directors since 2000. Mr. Margalit has been Managing General Partner of Jerusalem Venture Partners since August 1997. He was a general partner of Jerusalem Pacific Ventures from December 1993 to August 1997. From 1990 to 1993, Mr. Margalit was Director of Business Development of the City of Jerusalem. Mr. Margalit is a director of Paradigm Geophysical Ltd., Bridgewave Communications, Inc., CyOptics, Inc. First Access, Ltd., InLight Communications, Inc., KereniX, Inc., SANGate Systems, Inc., and Teleknowledge Group, Inc.

     James Wei has served on Cogent's board of directors since 2000. He has been a general partner at Worldview Technology Partners, a venture capital firm, since April 1996. Prior to that, Mr. Wei was a Fund Manager at JAFCO Co., Ltd., a venture capital firm, from October 1991 through April 1996. Mr. Wei currently also serves on the boards of directors for Caly Networks, CommVerge Solutions, Edge2Net, iWorld Networking, Movaz Networks, Tensilica, 3ParData, Triton Network Systems, and Wellspring Solutions. He is also a General Partner of Meritech Capital Partners, a late stage venture capital fund with $1.8 billion under management.

Board Composition

    Our board of directors currently consists of six directors. Upon consummation of the merger, we will increase the board of directors by one member and we will divide the board of directors into three classes: Class I, whose term will expire at the annual meeting of stockholders to be held in 2002; Class II, whose term will expire at the annual meeting of stockholders to be held in 2003; and Class III, whose term will expire at the annual meeting of stockholders to be held in 2004. The initial Class I directors will be Helen Lee, the individual designated by the Series C Preferred Stockholders and the individual designated by Allied Riser prior to the effective time of the merger, the initial Class II directors will be James Wei and Edward Glassmeyer, and the initial Class III directors will be Erel Margalit and David Schaeffer. At each annual meeting of the stockholders beginning in 2002, the successors to the class of directors whose terms expired will be elected to serve three-year terms. If the number of directors on our board increases, the newly created directorships will be distributed among the three classes so that each class will, as nearly as possible, consist of one-third of the directors. The classification of our board of directors may delay or prevent changes in our control or management. Our directors may be removed either with or without cause at any meeting of Cogent's stockholders by a majority vote of those stockholders represented and entitled to vote at such meeting.

Board Committees

    Our board of directors has established an audit committee and a compensation committee. The audit committee consists of Messrs. Glassmeyer, Margalit, and Wei. The audit committee meets periodically with management and our independent accountants to review their work and confirm that they are properly discharging their respective responsibilities. The audit committee also:

•

recommends the appointment of independent accountants to audit our financial statements and perform services related to the audit;

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•

reviews the scope and results of the audit with the independent accountants;



•

reviews with management and the independent accountants our annual operating results;



•

considers the adequacy of the internal accounting control procedures; and



•

considers the independence of our accountants.

    The compensation committee consists of Messrs. Glassmeyer, Margalit, and Wei. The compensation committee determines the salary and incentive compensation of our officers and provides recommendations for the salaries and incentive compensation of our other employees. The compensation committee also administers our stock option plan and our employee stock purchase plan, including reviewing management recommendations with respect to option grants and taking other actions as may be required in connection with our compensation and incentive plans.