Time Warner shares fall on reports that DOJ to make a major antitrust announcement involving AT&T

• The media company's stock was trading near the flatline before the news hit.
• AT&T shares, meanwhile, jumped about 1 percent.
• NBC News said, citing a source, that the announcement will involve AT&T.
• Reuters also reported, citing a source, that the Justice Department will sue AT&T to prevent it from buying Time Warner.

Jeffrey 'Jeff' Bewkes, chairman and chief executive officer of Time Warner Inc., listens during a Senate Judiciary Subcommittee hearing in Washington, D.C., U.S., on Wednesday, Dec. 7, 2016.

Andrew Harrer | Bloomberg | Getty Images

Shares of Time Warner fell 1.1 percent 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 about 3:15 p.m. New York time. AT&T shares, which is trying to complete a purchase of Time Warner for $85 billion, jumped about 1 percent before closing 0.4 percent higher.

NBC News said, citing a source, that the announcement will involve AT&T. Reuters also reported, citing a source, that the Justice Department will sue AT&T to prevent it from buying Time Warner.

AT&T and Time Warner have been seeking regulatory approval to complete the merger.

Earlier this month, there were allegations that the Justice Department demanded CNN be sold before approving the deal. The government pushed back against this notion, with an official telling CNBC the department just presented AT&T with several options by which it might be willing to satisfy antitrust concerns. It didn't, however, demand a sale of CNN.

White House Press Secretary Sarah Huckabee Sanders told reporters in a briefing that she was not aware of President Donald Trump or anyone at the White House encouraging pushing for the deal to get blocked.