Legal & General (L&G), the insurance and asset management group which owns Cala Group, is set to pick a new home for its housing subsidiary this week.
US-based investor Sixth Street has emerged as frontrunner to buy Cala, according to Sky News.
The firm has teamed up with Cala's former owner, Patron Capital Parterns, to try to win the race for the housebuilder.
Cala's rival Persimmon, which was reportedly weighing up a bid as far back as May, remains hopeful of striking a deal.
Cala, which started in 1875 as the City of Aberdeen Land Association, is likely to be valued somewhere between £1.2bn and £1.3bn, more than previously estimated.
The company could yet retain ownership of the housebuilder should no bid match its price expectations.
An announcement from L&G on the future of Cala Group is expected this week.