NEWARK, N.J.-Hedge-fund billionaire John Overdeck took to the witness stand last week to explain that he had always shared his riches with his wife, Laura Overdeck. That included the hundreds of millions of dollars in pay that he put into a joint account during their marriage, he said.

"In fact, she was able to withdraw $75 million the day before she filed for divorce," said Overdeck, co-founder of Two Sigma, the quant-trading powerhouse.

Overdeck didn't flinch when he mentioned the figure, just one of the many staggering sums being bandied about in a blockbuster divorce trial under way in a New Jersey courthouse. The trial could result in one of the largest divorce settlements ever and shake up the power struggle atop Two Sigma, where John Overdeck has been locked in a bitter feud with his co-founder, David Siegel.

John Overdeck is offering to give his estranged wife $723 million to settle their split. Laura Overdeck says their marital assets should include his stake in Two Sigma, which her attorney estimates is worth $6.2 billion. She wants 35% of that, or $2.17 billion.

The case is offering a view into how Wall Street's hedge fund titans generate their supersize wealth, and the lifestyle that money affords. It is also showcasing the complex strategies the superrich deploy to protect what they have earned. The onetime couple shared a life that included a 6,000-square-foot home in Short Hills, N.J., a charitable foundation with $900 million in assets and trust funds set up for family members, including the grandchildren they had one day hoped to welcome.

The unraveling of marriages among the ultrawealthy has long been a subject of fascination on Wall Street and beyond. Earlier this year, billionaire hedge-fund manager John Paulson settled his divorce case after a five-year legal battle in which his ex-wife sought more than $1 billion in damages. In their 2015 divorce settlement, Citadel Chief Executive Ken Griffin and Anne Dias agreed their prenuptial agreement was valid. It awarded Dias a $22.5 million payment, an additional $1 million for each year they were married and joint ownership of their Chicago penthouse.

The breakup of the Overdecks is a high-profile example of how messy a divorce can get, especially at upper-income levels, when the two sides don't have a prenuptial agreement.

Laura Overdeck has been present in the courtroom, wearing red-rimmed glasses and taking notes on a laptop. But she was barred from testifying or introducing her own witnesses after the court found that she obtained confidential emails from her husband's computer, among other violations.

The acrimony between the Overdecks, both 56, has been brewing for years. In 2023, a woman showed up at the couple's home, angry that John Overdeck had canceled their dinner plans, according to a New York Post report detailing a police video it said it obtained. He said in the video that they were dating, "but we've never had sex."

Laura Overdeck arrived on the scene at one point and told cops she wanted her soon-to-be ex gone, the Post reported.

On Tuesday, the trial will resume with the cross-examination of John Overdeck. Scheduling conflicts could mean the proceedings drag on for months.

'I was in love'

John Overdeck was an International Math Olympiad medalist as a teenager and graduated from Stanford. Laura holds degrees from Princeton and the Wharton School. The two met while working at investment firm D.E. Shaw & Co. in the 1990s, and began dating in 2001.

"I was in love," John Overdeck said from the stand, wearing a navy-blue suit and appearing unemotional. "And I was very optimistic about our ability to build a future together."

Overdeck founded Two Sigma with Siegel and Mark Pickard in 2001, and married Laura the next year.

In the following years, John and Laura had three children, with Laura handling much of the parenting, John Overdeck testified. He said she had the help of a full-time nanny who doubled as a personal secretary, and a housekeeper who worked 15 hours a week. Still, he said he tried to be as involved as possible, coaching the children's sports teams and rarely working weekends.

John Overdeck was also busy helping to expand Two Sigma. He said in court that his annual guaranteed payment from Two Sigma, akin to a base salary, was about $400,000 at the firm's founding and "hasn't grown that much." But he also got a share of the firm's investment profits, a form of pay known as carried interest that is aimed at ensuring managers' interests are aligned with those of their investors.

All told, he collected $685 million in pay while they were married, he said.

Overdeck distinguished between that compensation and the paper gains he made on the appreciation of his ownership stake in Two Sigma. While those gains were substantial in part because of the work he did for the firm, a good portion of them could be attributed to factors beyond his control, such as the growth of the hedge-fund industry and the run-up in equity markets, he said.

New Jersey separates gains on premarital assets tied to a spouse's work from those driven by the market. The latter isn't considered marital property, said Carl Soranno, chair of the family services practice at New Jersey firm Brach Eichler.

In early 2022, Laura filed for divorce, citing irreconcilable differences. In the police video cited by the Post, Laura Overdeck says she has "hotel receipts" when a cop suggests her husband and the woman who appeared at their home hadn't been dating.

A yearslong feud

The major physical asset in the case is the couple's New Jersey home.

John Overdeck said in court that he was willing to sell his half of the house to Laura at a value of about $6 million-after retrieving items including a Stanford crest, a painting of Arundel Castle that hung over the living room sofa and copies from boxes of mementos documenting the children's firsts.

Other assets discussed at trial include various trusts the couple set up over the years. One was a generation-skipping trust that borrowed money from John Overdeck to purchase interests in Two Sigma.

In a separate suit against the couple's estate-planning lawyers at Seward & Kissel, Laura Overdeck claimed they conspired with her husband to give him unilateral control over their trusts and family foundation from as early as 2005. John Overdeck's attorney has denied the claims.

The fight with the biggest price tag is John Overdeck's Two Sigma stake.

The sides don't even agree on how much that is worth, with his lawyers pegging it at $4.9 billion.

Attempts by Laura Overdeck's counsel to make public Two Sigma's finances have so far been blocked. Reporters and other observers were asked to clear the courtroom on several occasions so the parties could discuss matters the court had deemed nonpublic.

Any influence Laura Overdeck gains at Two Sigma could upset the delicate and unsteady power arrangement between the firm's founders.

Three years ago, Two Sigma disclosed a rift between John Overdeck and Siegel to investors as a material risk. Before stepping down as co-CEOs, Overdeck and Siegel rarely appeared together at firm events and frequently sniped at each other in meetings, The Wall Street Journal reported.

They settled on a new leadership structure where each could name one member to the firm's two-person management committee. The picks were named co-CEOs while Overdeck and Siegel remained Two Sigma's principal owners and co-chairmen, though Overdeck reappointed himself to the management committee last year.

The fix broke down earlier this year. Siegel replaced his designee on the management committee, who then tried to fire the co-CEO chosen by Overdeck.

"We recognize that recent media attention has extended to John Overdeck's divorce trial, and we expect it to continue," the firm said in a recent letter to investors. "This is a personal matter and we are not a party to those proceedings."