WASHINGTON (Reuters) – The U.S. Department of Justice will file a lawsuit aimed at blocking AT&T Inc’s $85.4 billion acquisition of Time Warner Inc, a source familiar with the matter told Reuters on Monday.

AT&T, the No. 2 U.S. wireless carrier, struck a deal in October 2016 to buy Time Warner, which owns the premium channel HBO, movie studio Warner Bros and news channel CNN, in order to compete by bundling mobile service with video entertainment.

Shares of Time Warner fell to trade about 1 percent lower on Monday on the back of reports that the U.S. government is set to make an antitrust announcement.

The media company’s stock was trading near the flatline before the news hit. AT&T shares, meanwhile, jumped about 1 percent. Bloomberg first reported the news.