8 January 1982: AT&T agrees to break itself up

After years of antitrust litigation, AT&T settled with the US Justice Department and agreed to divest its local telephone companies. The deal created seven regional Baby Bells in 1984 and opened long distance and equipment to competition. Shareholders received stakes in the new companies, and many did better owning the pieces than the whole. Ma Bell lost her monopoly; consumers eventually got cheaper calls and a lot more choice.

The lesson: Sometimes a forced breakup unlocks value that a sprawling monopoly was quietly sitting on.