Amgen Inc. (NASDAQ:AMGN) added $2 billion in market cap last Monday, which was nearly four times the value shaved off competitor Affymax Inc. (NASDAQ:AFFY) when the latter recalled its once-monthly anemia drug Omontys peginesatide.

Amgen went on to close the week at $92.58, a $5.76 gain that translates into a $4.3 billion market cap boost.