Company officials say Trizec Properties Incorporated and Metropolitan Life Insurance Company are negotiating a deal.
Trizec spokesman Rick Matthews says if it's successful, control of the world's second-tallest building will transfer to the New York-based MetLife.
Matthews says no agreement has been reached, and he's unsure when the company will conclude negotiations.
Chicago-based Trizec has reportedly had trouble attracting tenants to the building in the two years following the September Eleventh terrorist attacks.
As a result, the property's market value has dropped below the value of the outstanding loans.
Sears Tower is saddled with about $760 million in debt, which comes due in July 2005.