Barry Rosenstein has overseen a remarkable turnaround in the past two years that has put his activist-oriented hedge fund firm, Jana Partners, back on the map. The New York–based firm, which was founded in 2001, had placed among the world’s 100 largest hedge funds between 2006 and 2008, but the 2008 financial crisis hit the value-oriented, event-driven hedge fund firm hard. That year, the flagship fund dropped 23 percent, and by 2009, firmwide assets had settled at a $2 billion nadir from an $8.04 billion peak at the end of 2007. Jana Partners rose 20.4 percent in 2013 on the back of a strong 2012, when the flagship Jana Partners Fund was up 23 percent and Jana Nirvana Fund soared more than 33 percent. The flagship, which has averaged 13.9 percent returns since its 2001 launch through the end of April 2014, was helped in 2013 by tremendous performance in discount website Groupon, which soared 141 percent. The firm’s exceptional asset growth prompted Rosenstein to close the Jana Nirvana funds to outside investments beginning May 1, 2014…