Sculptor didn't identify the names of the bidding group in its statement, and said it "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."
The statement comes after Rithm Capital agreed in July to buy Sculptor in a deal valued at about $639 million, which is expected to be completed in the fourth quarter. The company had been embroiled in litigation with Dan Och over pay packages given to Sculptor Chief Executive Officer Jimmy Levin. The two resolved the legal dispute last year, and Sculptor formed a special committee to explore potential transactions.
In a proxy statement filed Monday, Sculptor revealed it received 70 bids after the firm's November announcement that it was looking for a buyer. The suitors included private and publicly traded alternative asset managers, financial services companies, a fintech company and others.
Mr. Och co-founded the firm formerly known as Och-Ziff before stepping down as chief executive officer in 2018.
Mr. Ackman declined to comment. Messrs. Lasry and Weinstein didn't reply to requests for comment.
Sculptor has faced a challenging last few years. The firm went public in 2007 and was one of the world's largest hedge funds by 2016, with assets approaching $50 billion, when it was buffeted by scandal. That year, a unit pleaded guilty to a conspiracy charge as a part of a settlement of a long-running U.S. probe into bribes paid to gain lucrative business in Africa.
Assets under management have since declined to around $34 billion. Sculptor's shares are down about 41% in the past five years.
Credit trading veteran Mr. Weinstein, who was thrust into prominence a decade ago after betting against the J.P. Morgan Chase & Co. trader known as the London Whale, runs Saba Capital Management. Mr. Ackman leads Pershing Square Capital Management, while Mr. Lasry is the co-founder of Avenue Capital Management.
Messrs. Weinstein and Ackman have previously publicly supported each other on common trades. Last year, Mr. Weinstein said he bet against the Hong Kong dollar, joining Mr. Ackman in publicizing his short position on the pegged currency and called the trade "a smart lottery ticket."