Cephalon, Inc. To Join The NASDAQ-100 Index Beginning June 1, 2007

Cephalon, Inc. (Nasdaq:CEPH) of Frazer, Pennsylvania, will become a component of the NASDAQ-100 Index(r) (Nasdaq:NDX), the NASDAQ-100 Equal Weighted Index (Nasdaq:NDXE), and the NASDAQ-100 Ex-Tech Sector Index (Nasdaq:NDXX) prior to market open on Friday, June 1, 2007. Cephalon, Inc. will replace MedImmune, Inc. (Nasdaq:MEDI).

With a market capitalization of approximately $5.3 billion, Cephalon, Inc. discovers, develops, and markets biopharmaceutical products to treat neurological disorders and cancer.

The NASDAQ-100 Index, launched in January 1985, is one of the most widely followed benchmarks in the world.