Alexion Pharmaceuticals Inc. (NASDAQ:ALXN) last week gave back most of the $900 million market cap pop gained from the prior Friday's rumors that it was going to be taken out by Roche (SIX:ROG; OTCQX:RHHBY). Alexion lost $3.54 to $103.42 on the week, ending with a market cap of $20 billion.

Shareholder Oliver Marti of Columbus Circle Investors said a takeout by Roche is unlikely because he thinks most biotech acquisition rumors