Flipping a coin is a truly random event. A coin will land on either heads or tails, and guessing right is a 50-50 proposition. The performance of actively-managed mutual funds is not as predictable. Funds that perform in the top half of their peer group during a five-year period had a less than 50% chance of staying in the top half during the next five-year period, according to a recent S&P Dow Jones study. Investors have better odds flipping a coin than using past performance to pick winning managers.