Rigel to offer 13,000,000 shares of its common stock at a price to the public of $7.25 per share

Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) today announced the pricing of an underwritten public offering of 13,000,000 shares of its common stock at a price to the public of $7.25 per share. All of the shares are being offered by Rigel. The underwriters have an option to purchase up to an additional 1,950,000 shares to cover over-allotments, if any. The offering is expected to close on September 22, 2009, subject to the satisfaction of customary closing conditions.

Credit Suisse Securities (USA) LLC is acting as the sole book-runner for the offering, with Oppenheimer & Co. Inc. and Thomas Weisel Partners LLC acting as co-managers.

A final prospectus supplement relating to these securities will be filed with the Securities and Exchange Commission. This press release does not constitute an offer to sell, or the solicitation of an offer to buy, these securities, nor will there be any sale of these securities in any state or other jurisdiction in which such offer, solicitation or sale is not permitted.

Copies of the final prospectus supplement and accompanying prospectus relating to the offering may be obtained from Credit Suisse Securities (USA) LLC, Prospectus Department, One Madison Avenue, New York, New York 10010-3629 (Telephone number 1-800-221-1037).