Fidelity Mutual Funds. Invest with a world leader in mutual funds * and you put a global network of 350+ research professionals and one of the largest research departments in the industry to work for you. 1 Our extensive resources allow Fidelity's fund managers to look deeply across different regions and sectors to find investment opportunities that others may miss. In April 2000, Vanguard's S&P 500 index fund displaced Magellan as the largest mutual fund in the world. By the time Stansky retired in 2005, the assets under management for Magellan were back down to $52.5 billion. Fidelity Investments operates a brokerage firm, manages a large family of mutual funds, provides fund distribution and investment advice, retirement services, Index funds, wealth management, cryptocurrency, securities execution and clearance, and life insurance.