AT&T Inc. won approval from a U.S. court on Tuesday to buy Time Warner Inc. for $85 billion, allowing AT&T to compete with internet companies that dominate digital advertising and providing new sources of revenue.

The planned deal is seen as a turning point for a media industry that has been upended by companies like Netflix Inc. and Google, which produce content and sell it online directly to consumers, without requiring a pricey cable subscription. Distributors including cable, satellite and wireless carriers all see buying content companies as a way to add revenue.

The ruling could also prompt a cascade of pay TV companies buying television and movie makers, with Comcast Corp.'s bid for some Twenty-First Century Fox Inc. assets potentially the first out of the gate.