Ahead of is full stock market listing, due to take place this week, Foxtons has been valued at £649m.
Foxtons announced their plans to float last month in order to raise funds and capitalise on the recovery in the property market.
The company is due to be officially admitted to the stock market on Wednesday but in conditional trading on Friday, shares were up more than 20%.
BC Partners, who bought the firm in 2007 for £360m, and other selling shareholders will get £335m from the sale, while a further £55m raised will be used to pay off company debts.
The shares floated represent 60% of the company, but BC Partners did not disclose how big a stake it had retained and how many were held by other minority shareholders.
Foxtons has said it is well-positioned to benefit from a recovery in property sales.
