Hedge fund Sculptor Capital Management, which in July agreed to be acquired Rithm Capital Corp in a deal valued at about $639m, has rejected an unsolicited rival bid from a group of hedge fund investors including Boaz Weinstein and Bill Ackman.

In a statement issued on Sunday in response to "a media inquiry", Sculptor wrote: “We have received an unsolicited proposal from a third party that had participated in the strategic alternatives process. This bidder has not demonstrated adequate committed funding for any of its bids."

The unsolicited bid, believed to be from the group led by Weinstein, is worth more than $12 a share, according to the Wall Street Journal, bettering Rithm's $11.15 a share offer.

In the statement through Scupltor wrote that while the "headline valuation is higher than the Rithm transaction", the rival bid "only includes committed financing for less than half of the amount required to consummate the transaction and underestimates the amount that would be necessary by several hundred million dollars".