Tribune Media Co. on Thursday terminated its planned $3.9 billion merger with Sinclair Broadcast Group Inc. and sued to recover $1 billion from its former deal partner for allegedly failing to obtain regulatory approval for a transaction that would have created a conservative news giant capable of reaching 72 percent of U.S. households.

The lawsuit, filed by attorneys from Debevoise & Plimpton, seeks to avoid what Tribune said could have been years of administrative delay and instead asked the Delaware Court of  Chancery to rule that Sinclair breached its contractual duties to make “reasonable best efforts” to close the deal quickly.