Similar to the year-end window dressing conducted by fund managers to dress up their portfolios, the FDA now is well into its year-end spate of product approvals. Investors, however, don't necessarily use this ultimate milestone to celebrate.

The agency on Thursday approved Protein Design Labs' Zenapax humanized monoclonal antibody to prevent kidney transplant rejection. But the stock lost 22 percent on the week to $36.875. Investors had knocked 16 percent off the stock on Tuesday, after Boehringer Mannheim returned all rights to PDLI's human anti-hepatitis B and human anti-cytomegalovirus antibodies (see Technology Briefing, A3).