Mutual funds provide professional management of diversified portfolios for individual investors. They calculate a daily net asset value (NAV) per share, which is used to price purchases and redemptions. While open-end funds issue and redeem shares continuously at NAV, closed-end funds trade on exchanges and may trade at prices above or below NAV. Mutual funds recently faced fraud investigations over permitting some investors to make short-term trades or late-day trades against stated policies.