Randall Stephenson

The head of one of the nation’s largest employers (and, with $163.8 billion in revenue last year, one of the world’s largest companies), Stephenson has taken on a challenge befitting AT&T’s stature: retraining more than 100,000 workers. In the face of rapid technological change, many CEOs have cut their people loose. But AT&T is launching a roughly billion-dollar push to teach them new skills through its sweeping 2020 initiative. The drive is already paying off: Last year AT&T filled more than 40% of open positions with internal candidates.