Photo by Scott Olson/Getty ImagesViking Global Equities, the $30 billion-plus hedge fund led by Andreas Halvorsen, bought more Valeant Pharmaceuticals stock in the fourth quarter even after it dragged down the fund's performance. Viking Global had a strong 2015 overall, finishing up 8.3% for the year, according to the fund's fourth-quarter letter dated January 14. The average hedge fund finished 2015 down 3.49%, according to HFR.