With a $3.3 billion windfall, Elan Corp. plc (NYSE:ELN) has said it plans to shop for new assets and give some money back to shareholders over time. Investors seem less than enthused, however, and sent the shares down $1.06 to $9.40 on Wednesday after the biotech agreed to restructure a 2000 deal for multiple sclerosis drug Tysabri natalizumab with Biogen Idec Inc. (NASDAQ:BIIB).

It's possible that Elan shareholders with long memories are having a sense of déjà vu. The company has restructured, sought alternatives and/or sold off chunks of its business almost a dozen times since