In January 2000, America Online and Time Warner announced the largest merger in U.S. history, a deal that would create the biggest media company in the world. It was celebrated as the marriage of new media and old media, a potent combination of the nation's No. 1 Internet company and the country's leading entertainment giant, the owner of such internationally renowned brands as Warner Bros., HBO, CNN, and Time magazine.
But only three years later, nearly all the top executives behind the merger had resigned, the company had lost tens of billions of dollars in market value, and the...