Arena Pharmaceuticals, Inc.
Mar 2, 2006

Arena Pharmaceuticals Announces Exercise of Over-Allotment Option by Underwriters

SAN DIEGO, Feb 02, 2006 /PRNewswire-FirstCall via COMTEX News Network/ -- Arena Pharmaceuticals, Inc. (Nasdaq: ARNA) announced today that the underwriters have exercised an over-allotment option to purchase an additional 885,016 shares of its common stock in connection with its follow-on stock offering that priced on January 26, 2006. Including the over-allotment shares being purchased, the offering will total 10,637,524 shares at a public offering price of $16.90 per share, resulting in expected net proceeds to the company of approximately $169.4 million.

CIBC World Markets Corp. and UBS Investment Bank are acting as joint book-running managers in this offering. Needham & Company, LLC, Piper Jaffray & Co., SG Cowen & Co., LLC, Morgan Joseph & Co. Inc. and Montgomery & Co., LLC are acting as co-managers.

A registration statement relating to these securities was filed and has been declared effective by the Securities and Exchange Commission. Sales of shares pursuant to this offering may be made only by means of the final prospectus supplement and related prospectus, copies of which can be obtained from CIBC World Markets Corp. by email at useprospectus@us.cibc.com or by fax at 212-667-6303, or from UBS Investment Bank, Prospectus Department, 299 Park Avenue, New York, NY 10171 or by phone at 888-827-7275. This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of, these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such jurisdiction.

SOURCE Arena Pharmaceuticals, Inc.

Jack Lief, President and CEO, or David Walsey, Director, Corporate Communications, both of Arena Pharmaceuticals, +1-858-453-7200, ext. 1682; or Carin Canale, Media & Investor Relations of Porter Novelli Life Sciences, +1-858-336-3027, for Arena Pharmaceuticals, Inc.