AT&T has reached an agreement in principle to buy Time Warner for about $85 billion, sources said on Friday, paving the way for the biggest deal in the world this year. The agreement would give the telecom company control of the cable TV channels HBO and CNN, the film studio Warner Bros. and other coveted media assets.

The deal, which has been agreed upon in most of its terms and could be announced as early as Sunday, would be one of the largest in recent years in the sector as telecommunications companies look to combine content and distribution to capture customers who are replacing traditional pay-TV packages with more streamlined offerings and online delivery.

AT&T, which sells wireless phone and broadband services, has already made moves to turn itself into a media powerhouse, buying the satellite TV provider DirecTV last year for $48.5 billion.