AT&T cast light on its pending spinoff of WarnerMedia to Discovery this past week—a big step toward putting a decade of misguided mergers and acquisitions behind it. AT&T spent years dishing out billions of dollars on deals, including $66 billion for DirecTV in 2015 and $106 billion for Time Warner in 2018. These brought the 145-year-old phone company into new, more-cyclical industries, and at one point made it the most indebted company in the U.S.
Under new CEO John Stankey, AT&T has slimmed down. AT&T spun off DirecTV and…