Topland Group, which is run by Sol Zakay, has emerged as the latest possible suitor for embattled Harry Macklowe's trophy buildings in New York.
Topland has yet to submit a formal bid.
Macklowe needs to pay off $7bn in short-term debt on buildings he bought last year from Equity Office Properties via Blackstone Group - or face foreclosure on the GM Building, which he bought in 2003 for $1.4bn and which he pledged against the loans.
The credit crunch left Macklowe unable to pay back $1.35bn to Fortress Investment Group and $5.8bn to his long-time lender, Deutsche Bank.
Topland is said to be interested in a portfolio of properties comprising the famous GM building and seven other properties Macklowe owned prior to buying the EOP portfolio.
The portfolio includes buildings such as 1330 Sixth Avenue and 2 Grand Central Tower in Manhattan.
The portfolio is being marketed by Citigroup and CB Richard Ellis. Jones Lang LaSalle is advising Topland.