The transaction, announced on Monday, follows Tribune’s acquisition of Local TV and Gannett Co’s purchase of Belo Corp.
Sinclair’s stock rose 1.3 percent to $30.16.
“To buy a full-blown news operation in our nation’s capital and an infrastructure that allows us to be connected to our branches of government and be at the pulse of national issues is a once-in-a lifetime event,” Sinclair President David Smith said in a statement.
Baltimore-based Sinclair is the largest U.S. TV broadcasting group, with stations in Minneapolis, Salt Lake City and Austin, Texas, according to the company.
Including the Allbritton deal, Sinclair’s net revenue would have been $1.8 billion in 2012.
Moelis & Co served as financial adviser to Allbritton.