SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. __) Filed by the Registrant [ ] Filed by a Party other than the Registrant [x] Check the appropriate box: [ ] Preliminary Proxy Statement [ ] Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) [ ] Definitive Proxy Statement [X] Definitive Additional Materials [ ] Soliciting Material Pursuant to ss. 240.14a-12 IMCLONE SYSTEMS INCORPORATED (Name of Registrant as Specified In Its Charter) CARL C. ICAHN ALEXANDER J. DENNER PETER S. LIEBERT BARBERRY CORP. HIGH RIVER LIMITED PARTNERSHIP AND HOPPER INVESTMENTS LLC (Name of Person(s) Filing Proxy Statement, if other than the Registrant) Payment of Filing Fee (check the appropriate box): [X] No fee required. 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Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing. 1) Amount Previously Paid: 2) Form, Schedule or Registration Statement No.: 3) Filing Party: 4) Date Filed: On October 6, 2006, Institutional Shareholder Services ("ISS") "M&A Insight" put out a note to clients discussing Carl Icahn's recent activism at ImClone Systems Incorporated. On October 9, 2006, ISS spoke with Mr. Icahn to get his version of the events surrounding the Consent Solicitation and subsequently Mr. Icahn provided written comments to Chris Young on a draft of the attached note. A copy of the M&A Insight Note summarizing the October 9, 2006 conversation is filed herewith as Exhibit 1. EXHIBIT 1 INSTITUTIONAL SHAREHOLDER SERVICES M&A Insight Note Issuer: ImClone Systems (IMCL)/"A Conversation with Carl Icahn" Date: October 18, 2006 On Oct. 6, M&A Insight put out a note to clients discussing Carl Icahn's recent activism at ImClone Systems (IMCL). In the note, we indicated that Mr. Icahn's actions (including seeking the resignation of board chairman David Kies and launching a consent solicitation to gain control of the board) appeared to be rather aggressive in light of the recent settlement reached by the two combatants. We noted that Mr. Icahn's actions are likely to be used by IMCL (and by future targets of Mr. Icahn) as "evidence" that Mr. Icahn is not to be trusted and is unable to work constructively with incumbents. On Oct. 9, we spoke with Mr. Icahn to get his side of the story. Mr. Icahn stressed that at the time he accepted the offer of his board seat he had no intention of conducting a consent solicitation. He made it clear that because it takes a plurality of votes to win a proxy fight and a majority of outstanding shares to win a consent solicitation, it would have been "ridiculous" for him to have given up the chance to conduct a proxy fight in order to join the board and then conduct a consent solicitation to remove directors. Mr. Icahn also stated that prior to this year's annual meeting, IMCL approached him to try to reach an amicable settlement of their differences. Prior thereto, Mr. Icahn had hired Alex Denner, who was a director of IMCL. IMCL then offered to nominate Mr. Denner, Mr. Icahn and two persons suggested by him who were among those vetted by the company. Mr. Icahn agreed not to nominate others for election at the annual meeting. During the discussions with IMCL, Mr. Icahn claims he made it very clear to the company that he believed IMCL needs a CEO who has significant biotech experience. Mr. Icahn notes that Joseph Fischer, the company's interim CEO, has no biotech experience. Mr. Icahn alleges he clearly warned the company against giving Mr. Fischer a long-term employment contract during settlement discussions. However, on Aug. 23, the same day IMCL and Mr. Icahn announced the settlement agreement, the company also disclosed an amendment to Mr. Fisher's employment agreement. Mr. Icahn claims he was not notified of this amendment before its adoption. In addition, Mr. Icahn says that during discussions he had with Mr. Kies, Mr. Kies indicated he had no interest in continuing as chairman. However, on Sept. 20, the same day as the annual meeting at which Mr. Icahn, Denner and two persons suggested by Icahn were elected to the board, Mr. Kies called for a board vote on his own chairmanship and subsequently was re-elected chairman. Mr. Icahn characterizes this move as a betrayal of the representations made to him during settlement discussions. In short, Mr. Icahn believes that the company never seriously considered addressing his concerns about the company's chairman and CEO and that IMCL had been warned that by not taking the action that he suggested, they would be "throwing down the gauntlet." If Mr. Icahn's version of events are accurate, it helps to explain the unusually rapid deterioration of relations between the dissident and the target company so soon after an announced settlement. We note that a day after our conversation with Mr. Icahn, the company announced the resignation of Mr. Kies and another director, William Crouse. This development appears to address one bone of contention of Mr. Icahn's; however, the suitability of the company's CEO presumably remains at issue. Unfortunately for shareholders, nearly every proxy fight becomes a "he said, she said" exercise, a tough dynamic to analyze from the outside. One of the goals of M&A Insight is to help interested constituencies to better analyze a sometimes confusing debate. We will continue to monitor this situation and market trends, speak with interested parties and, where relevant, issue additional M&A Insight Notes to provide further information and guidance for clients. Please note that this M&A Insight research note should not be interpreted as an indication of how ISS ultimately will recommend shareholders vote on the proposed transaction. M&A Insight research notes are designed to highlight key issues facing shareholders in selected high-profile or contentious transactions. This issuer may have purchased self-assessment tools and publications from the Corporate Service division of Institutional Shareholder Services Inc. ("ISS"), or the Corporate Services division of ISS may have provided advisory or analytical services to the issuer in connection with the proxies described in this report. Neither the issuer nor any corporate services division employee played a role in the preparation of this report. To inquire about any issuer's use of Corporate Services products from ISS, please email disclosure@issproxy.com This proxy analysis and vote recommendation have not been submitted to, nor received approval from, the United States Securities and Exchange Commission or any other regulatory body. While ISS exercised due care in compiling this analysis, we make no warranty, express or implied, regarding the accuracy, completeness, or usefulness of this information and assume no liability with respect to the consequences of relying on this information for investment or other purposes. In particular, the research and voting recommendations provided are not intended to constitute an offer, solicitation or advice to buy or sell securities. This issuer may be a client of ISS or the parent of, or affiliated with, a client of ISS. Neither the issuer, nor any of its subsidiaries or affiliates, played any role in preparing this report. Some of our clients may own stock in the issuer that is the subject of this report. Two of ISS' stockholders, Warburg Pincus Private Equity VIII, L.P. and Hermes USA Investors Venture, L.L.C., are institutional investors whose business activities include making equity and debt investments in public and privately-held companies. As a result, from time to time one or more of ISS' stockholders or their affiliates (or their representatives who serve on ISS' Board of Directors) may hold securities, serve on the board of directors and/or have the right to nominate representatives to the board of a company which is the subject of one of ISS' proxy analyses and vote recommendations. We have established policies and procedures to restrict the involvement of ISS' non-management stockholders, their affiliates and board members in the editorial content of our analyses and vote recommendations. Deminor Rating SA ("Deminor/ISS Europe") is a wholly-owned subsidiary of ISS. Jean-Nicolas Caprasse, the managing director of Deminor/ISS Europe, is a non-executive partner of Deminor International SCRL ("International"), a company which provides active engagement and other advisory services to shareholders of both listed and non-listed companies. As a result, International may be providing engagement services to shareholders of a company which is the subject of one of our analyses or recommendations or otherwise working on behalf of shareholders with respect to such a company. As a non-executive partner of International, Mr. Caprasse is not involved in the engagement and other services provided to the clients of International. International has no role in the formulation of the research policies, reports and vote recommendations prepared by ISS or Deminor/ISS Europe. Mr. Caprasse will benefit financially from the success of International's business in proportion to his partnership interest. Neither ISS' non-management stockholders, their affiliates nor ISS' non-management board members are informed of the contents of any of our analyses or recommendations prior to their publication or dissemination. Contact: Chris Young, JD, CFA Qin Tuminelli, CFA Director & Head of M&A Research Manager, M&A Insight Tel. 301.556.0625 Tel. 301.556.0415 Christopher.young@issproxy.com Qin.tuminelli@issproxy.com (C) 2006, Institutional Shareholder Services Inc. All Rights Reserved. The information contained in this ISS Proxy Analysis may not be republished, broadcast, or redistributed without the prior written consent of Institutional Shareholder Services Inc.