Fidelity's Magellan mutual fund was once that most admired mutual fund in the industry from the mid-1970s until the early 1990s. The legendary fund manager Peter Lynch steered the fund to whopping 29% annual returns during his years at the helm between 1977 and 1990. A $10,000 investment in Magellan in 1977 would have grown to $288,000 by 1990, as discussed in this article.
Unfortunately, Magellan's performance has lagged for the past 10+ years due to bad investments by its managers. Its huge size has also been a hindrance, as enormous growth-oriented mutual funds have difficulty closing positions in growth stocks without adversely affecting the price of stocks it is selling.
According to this recent article in Fortune magazine, Magellan is currently mired in its second-worst performance slump relative to the S&P 500 index in 30 years.