Learn about Jana Partners, an event-driven, activist hedge fund founded by Barry Rosenstein. : Jana Partners is an activist hedge fund founded by Barry Rosenstein in 2001. The fund specializes in event-driven investing by applying a fundamental analysis to identify undervalued companies in the market. The firm also engages in activist investing which can potentially serve as an event-driven, fundamental investing catalyst. Jana Partners is based in New York. The fund manages around $5.35 billion with $3.78 billion in 13F equity holdings as of June 30, 2018.