News outlets including Reuters, the New York Times and CNN, attributing the news to sources, said a deal could be announced as soon as Monday. The Sinclair offer values Tribune Media at around $44 per share, according to Reuters.
Tribune Media shares ended trading on Friday at $40.29, giving it a market capitalization of $3.5 billion.
Sinclair, one of the largest television station operators in the country, is headquartered in Hunt Valley. It owns WBFF Fox 45, a local CW affiliate and My TV Baltimore.
Tribune Media was created in 2014 when then-Baltimore Sun parent Tribune Co. split its broadcasting and publishing divisions into separate, independent companies.
The broadcast division became Tribune Media. The publishing division, including The Sun, became Tribune Publishing. Tribune Publishing last year became tronc Inc., short for Tribune online content.
Tribune Media retained ownership of The Baltimore Sun building on North Calvert Street. The company put the building and much of its other real estate up for sale last year. Baltimore-based Atapco Properties has said it is in due diligence to buy it. The Sun has a lease for the property with an option to renew.
The acquisition would be the first major deal between broadcasters since the U.S. Federal Communications Commission voted to reverse a decision that limited the number of television stations broadcasters may buy.
Media outlets reported that negotiations between Sinclair and Tribune Media have not been finalized, and there is still a possibility a deal will not be reached.
Neither Tribune Media nor Sinclair responded to the Sun's requests for comment.