http://www.fool.com/investing/general/2013/02/17/my-favorite-big

The link gives some comparison among several biotech stocks. All of them have reasonably well return. My guess is that GILD may provide annual return bewteen 30 percent to 50 percent in 2013 (of course, nobody can precisely and surely predict what is going to happen in the future). If one wants to buy a certain stock, he or she must do a complete research on the stock's historical performance as well as its competitors and all the related big news which might affect the stock's performance in the future. Never simply follows others' suggestion and you must do your own homework because you are the one who is responsible for the gain or loss of your investment. Good luck!