SEMI-ANNUAL CHANGES TO THE NASDAQ BIOTECHNOLOGY INDEX

New York, N.Y.—The Nasdaq Stock Market, Inc. (NASDAQ) announced today the results of the semi-annual re-ranking of the NASDAQ Biotechnology Index® (NASDAQ: NBI), which will become effective with the market open on Monday, May 19, 2003.

The following issues will be added to the Index: Corixa Corporation (NASDAQ: CRXA); ID Biomedical Corporation (NASDAQ: IDBE), MGI Pharma Inc. (NASDAQ: MOGN); PRAECIS PHARMACEUTICALS INCORPORATED (NASDAQ: PRCS); SciClone Pharmaceuticals, Inc. (NASDAQ: SCLN); and XOMA Ltd. (NASDAQ: XOMA).

Corixa Corporation, headquartered in Seattle, Washington, is a developer of immunotherapeutics for the treatment and prevention of cancer, infectious diseases and autoimmune diseases. Corixa currently has multiple programs in clinical development, including several product candidates that have advanced to or through late stage clinical trials.

ID Biomedical Corporation, headquartered in Vancouver, British Columbia, is focused on the development of proprietary subunit vaccine products, including those based on its Proteosome(TM) platform intranasal adjuvant/delivery technology. The company has also developed a proprietary genomics analysis system, Cycling Probe(TM) Technology. The Company's lead products in clinical development are the FluINsure(TM) intranasal influenza (flu) vaccine and the StreptAvax(TM) group A streptococcal vaccine. Additionally, the Company has a number of vaccines in preclinical development.

MGI PHARMA, Inc., headquartered in Bloomington, Minnesota, is an oncology-focused biopharmaceutical company that acquires, develops and commercializes proprietary products that address the unmet needs of cancer patients. The Company directly markets its products in the U.S. including Salagen® Tablets (pilocarpine hydrochloride) and Hexalen^® (altretamine) capsules and collaborates with various alliances in international markets.

PRAECIS PHARMACEUTICALS INCORPORATED, headquartered in Waltham, Massachusetts, is focused on the discovery and development of pharmaceutical products using its proprietary LEAP(TM) (Ligand Evolution to Active Pharmaceuticals) technology. PRAECIS employed LEAP(TM) in the development of Plenaxis(TM), its candidate for the treatment of hormonally responsive advanced prostate cancer and endometriosis.

SciClone Pharmaceuticals, headquartered in San Mateo, California, is engaged in the development of therapeutics to treat life-threatening diseases. Its lead product ZADAXIN is in several late-stage clinical trials for hepatitis B & C, malignant melanoma and liver cancer. In addition to ZADAXIN, the company's drug development opportunities include SCV-07, a potentially orally available therapy to treat viral and infectious diseases, and products to address the protein-based disorder that causes cystic fibrosis.

XOMA Ltd., headquartered in Berkeley, California, develops and manufactures antibody and other protein-based biopharmaceuticals for disease targets that include cancer, immunological and inflammatory disorders, and infectious diseases. XOMA's programs include collaborations relating Raptiva(TM) antibody for psoriasis, rheumatoid arthritis, psoriatic arthritis and other indications; NEUPREX (R)(rBPI21) for Crohn's disease and other indications; and on two biotherapeutic agents, CAB2 and MLN01, for certain vascular inflammation indications.

As a result of the re-ranking, Emisphere Technologies, Inc. (EMIS) and EntreMed, Inc. (ENMD) will be removed from the Index.

The NASDAQ Biotechnology Index includes companies primarily engaged in using biomedical research for the discovery or development of novel treatments or cures for human disease. In addition, all securities in the Index are listed on the NASDAQ National Market and meet minimum requirements for market value, average daily share volume and seasoning as a public company. The Index is ranked on a semi-annual basis in May and November. For more information about the NASDAQ Biotechnology Index, including eligibility criteria, visit www.NASDAQ.com.

The NASDAQ Biotechnology Index is the basis for the iShares N-asdaq Biotechnology Index^SM Fund (Amex: IBB), which seeks investment results that generally correspond to the price and yield performance of the NASDAQ Biotechnology Index before fees and expenses. In addition, options based on the NASDAQ Biotechnology Index and the iShares Nasdaq Biotechnology Index Fund trade on --various exchanges.

With approximately 3,530 companies, NASDAQ lists more companies and, on average, trades more shares per day than any other U.S. market. It is home to category-defining companies that are leaders across all areas of business including technology, retail, communications, financial services, media and biotechnology industries. For more information about NASDAQ, visit the NASDAQ Web site at www.NASDAQ.com or the NASDAQ Newsroom^SM at www.nasdaq.com/newsroom.

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