A New York appeals court has revived a lawsuit by the former wife of Steven Cohen, the founder of the hedge fund SAC Capital Advisors, who accused the billionaire of hiding $5.5m (£3.6m) from her during proceedings that led to their 1990 divorce.
The appeals court ruled that a lower court had erred in dismissing fraud-based claims by Patricia Cohen, who had sued her ex-husband in 2009.
It also revived claims of racketeering and breach of fiduciary duty, while upholding the dismissal of an unjust enrichment claim.
Circuit Judge Pierre Leval said Mrs Cohen had made a "plausible" allegation that Steven Cohen concealed the $5.5m during negotiations on a separation agreement in 1989, which preceded the divorce. He noted that the court's decision did not address whether Mrs Cohen's fraud claims had merit.
A spokesman for SAC Capital Advisors said: "These decades-old allegations by Mr Cohen's former spouse were patently false."
The decision is another setback for Mr Cohen, whose fund has faced a federal insider trading inquiry. Last month it offered a $616m settlement without admitting wrongdoing.