The Fidelity Magellan Fund is a U.S. mutual fund that became the world's most famous actively managed investment vehicle, largely due to legendary manager Peter Lynch, who led it from 1977 to 1990. Under Lynch, the fund averaged a staggering 29% annual return, making it the best-performing mutual fund globally, while growing assets from $20 million to $14 billion by using his "Buy What You Know" strategy and holding an unconventional portfolio of up to 1,400 stocks. At its peak, Magellan surpassed $100 billion in assets and remained the world's largest mutual fund until Vanguard's S&P 500 index fund displaced it in April 2000. Because its enormous size made it difficult to beat the market, Fidelity closed the fund to new investors on September 30, 1997, but announced it would reopen on January 14, 2008, for the first time in over a decade. Other notable highlights include the fund's best-ever annual return of 116.08% in 1965 and Lynch's 1989 best-seller One Up on Wall Street, which popularized his "growth at a reasonable price" (GARP) approach.