Carl Icahn's patience and persistence in agitating for the sale of Amylin Pharmaceuticals Inc. (NASDAQ:AMLN) paid off when Bristol-Myers Squibb Co. (NYSE:BMY) agreed to pay $31 per share for the diabetes company, which would translate into a 34% return for the activist investor.

In April, Icahn reported in an SEC filing that he bought his 14.4 million shares - or 8.8% stake in Amylin - for an average price of $23.30.