BC Partners has entered into exclusive talks with UK estate agent Foxtons to buy the firm for £400 million ($796 million, €588 million), according to UK newspaper The Times.
Jon Hunt, the agency founder, is thought to own around 90 percent of the firm.
Foxtons has been the subject of speculation over the last few months with both US buyout firm TA Associates and London-listed firm 3i thought to be interested in the company. 3i is believed to have pulled out of the bidding a fortnight ago.
US buyout firm Apollo Management recently bought UK property firm Countrywide for £1.1 billion at the beginning of this month after seeing off a dramatic last minute challenge from 3i.