Last month, the Federal Communications Commission voiced concerns that Sinclair may have attempted to skirt ownership rules, and ordered the potential transaction to go through an administrative hearing.
Sinclair already has 173 stations around the country, including KENV in Salt Lake City, KOMO in Seattle and WKRC in Cincinnati.
"In light of the FCC's unanimous decision, referring the issue of Sinclair's conduct for a hearing before an administrative law judge, our merger can not be completed within an acceptable timeframe, if ever", said Peter Kern, Tribune Media's Chief Executive Officer, in a release. A sticking point for regulators at the FCC and the Justice Department was a series of side deals that Sinclair had proposed in order to bring the combined company into compliance with regulations on the number of local TV stations a company could own. Sinclair also refused to sell certain stations that would have helped the deal secure regulatory approval, Tribune claimed in a news release.
'To maintain control over stations it was obligated to sell, Sinclair engaged in unnecessarily aggressive and protracted negotiations with the Department of Justice and the FCC over regulatory requirements, ' Tribune said.
Sinclair owns or operates 173 broadcast TV stations in 81 markets, while Tribune has 42 stations in 33 markets.
Tribune seeks about $1 billion of lost premium to Tribune's stockholders and additional damages in an amount to be proven at trial, according to a copy of the lawsuit filed in Delaware.
Sinclair did not respond to a request for comment Thursday morning. Sinclair has been scrutinized for its ties to the Trump administration.
The deal's termination, which scuppers Sinclair's efforts to dramatically expand, comes after criticism by Democrats and public advocacy groups over whether the merger was in the public interest.
Tribune Media is a parent company of WGN-TV.
The two companies had until midnight Wednesday to call off their deal.
Mike Huckabee, (R-Ark.), and FBN's Maria Bartiromo and Kristina Partsinevelos on Tribune Media terminating its merger agreement with Sinclair Broadcast Group. Sinclair defended the script as a way to distinguish its news shows from unreliable stories on social media.
'So sad and unfair that the FCC wouldn't approve the Sinclair Broadcast merger with Tribune.
The announcement brings an end to a merger that was thought to have a staunch champion in FCC Chairman Ajit Pai, whose tenure had been marked by a deregulatory agenda that had cleared out restrictions against consolidation in the media industry.
The FCC's concerns followed similar questions raised in separate filings by the American Civil Liberties Union and conservative news outlet Newsmax Media.