Abigail Johnson

Abigail Johnson couldn't have been handed the reins at a tougher time. It was May 2001, squarely amid the worst bear market since the 1930s, when she was promoted to president of Fidelity Management & Research and put in charge of investment operations. Who put her there? Her father Edward C. (Ned) Johnson III, whose own father founded the mutual-fund giant in 1946. So you could say she's had a comfort level most executives never enjoy. There's also the cushion of being worth nearly $10 billion as heir to the privately held Fidelity juggernaut. "She's cool and calm, and she works hard every day," says Eric Kobren, editor of the independent newsletter Fidelity Insight. "She doesn't have that air of being one of the richest people in the world." Or of managing one of the world's largest pots of money, $893 billion in mutual-fund assets.

Johnson, 42, has seen to it that Fidelity's technology is the envy of the industry. An analyst can walk out of a CEO meeting anywhere in the world and within minutes determine which fund managers are interested in the stock, and file a research note to them. Now she's reinvigorating a performance-driven culture, giving Fidelity some sizzle by encouraging managers to make bigger bets on their best ideas. That's how Peter Lynch turned Fidelity into a household name. Ned Johnson has been speaking for the firm during the fund scandals that erupted last fall; he'll take the heat if trouble reaches Fidelity's doors. But very soon, trouble or no, his daughter will be in control--and by all accounts she's ready. --By Daniel Kadlec