Billionaire investor Steven A. Cohen on Thursday won the dismissal of a long-running lawsuit in which his former wife accused him of cheating her out of millions of dollars in their 1990 divorce.

Chief Judge Loretta Preska of the U.S. District Court in Manhattan said Patricia Cohen failed to show that her former husband defrauded her by hiding $5.5 million from a 1986 New York City real estate transaction, allowing him to lowball his net worth.

The divorce came two years before Steven Cohen created his Stamford, Connecticut-based hedge fund firm SAC Capital Advisors, where he made his name on Wall Street and his fortune. Forbes magazine estimates his net worth at $12.7 billion.

"We respectfully disagree with the decision," said Gerald Lefcourt, a lawyer for Patricia Cohen. "If all the evidence were put before a jury we believe a jury would find for Mrs. Cohen. Fortunately, she can choose to pursue an appeal."

A spokesman for Steven Cohen did not immediately respond to a request for comment.

In her lawsuit, Patricia Cohen said she was entitled at least half of the $5.5 million at issue, plus interest.

But the judge found "no evidence that Steven concealed any assets from Patricia during the divorce," and that no reasonable jury could find that he committed fraud.

Preska also said the record showed that Patricia Cohen "suspected Steven of fraud in 1991 and 2006," and waited too long by not suing him until December 2009.

After SAC pleaded guilty to insider trading and paid $1.8 billion in settlements with U.S. authorities, Cohen converted the firm into Point72 Asset Management, a family office that trades mostly his money.

Cohen was not charged with insider trading, and is eligible to resume managing outside money in 2018.