The back story. Shares of Pfizer (PFE) are down 15.6% since the company announced in late July that it would spin off Upjohn, the division that sells off-patent drugs like Viagra and Lipitor. Upjohn will merge with Mylan to create a new company, while Pfizer will be left as a dedicated biopharma company. The S&P 500 is down 0.6% over the same period.