Many hedge funds are drastically underperforming the markets this year. In fact, since 2004, the majority of hedge funds have underperformed the broader markets, despite the huge bull market in stocks.Since most hedge funds get paid based on their returns for the year, managers who don't want to underperform often turn to shareholder activism as a way to increase shareholder value and ultimately boost their returns. At Stockpickr, we track many of the latest activist situations. We highlight a few here. Activist hedge fund Harbinger Capital Partners has purchased a 5.9% stake in starch goods company Corn Products International ( CPO). Harbinger disclosed that it owns about 4.34 million shares of Corn Products. Corn Products has a forward P/E of 13, a PEG ratio of 1.5 and quarterly earnings growth of 29%. The corn refiner also recently boosted its 2008 profit guidance and reported a 29% rise in first-quarter profit. Keep an eye on this one. Another stock to watch is biotechnology company Biogen Idec ( BIIB). Billionaire activist investor Carl Icahn filed a proxy document on Friday to nominate three directors to Biogen's board of biotechnology. Icahn, who has claimed that Biogen sabotaged an auction to sell itself, is nominating Alexander Denner, managing director of his Icahn Partners investment vehicle; Richard Mulligan, professor of genetics at Harvard Medical School; and Dr. Anne Young, head of the neurology service at Massachusetts General Hospital, to become Biogen directors.