(FORTUNE Magazine) – When Jack Welch retired in 2001, Immelt won one of the toughest succession battles ever to become the ninth CEO of the hugely respected 125-year-old corporate giant, beating out such rivals as Bob Nardelli (now CEO of Home Depot) and Jim McNerney (CEO of 3M). Immelt has big shoes to fill, and he has been dealt a tough hand. But he has gracefully coped with problems from a choppy economy to Wall Street demands for greater transparency. He ditched misfits like GE's Japanese life insurer and divided the once-opaque GE Capital into four units, appeasing investors. Meanwhile, he has maintained the strength of key businesses like NBC, which reaches 6.2 million viewers every morning--more than any other network--and snagged the U.S. rights to air the 2010 and 2012 Olympic Games. All this, and he's only 47. That means he has 18 years to catch up to Jack before hitting GE's traditional retirement age. --Julie Schlosser