A hedge-fund billionaire’s two bitter wars—against his wife and his business partner

Hedge-fund billionaire John Overdeck, 56, is simultaneously fighting a divorce trial with his estranged wife, Laura Overdeck, and a protracted power struggle with Two Sigma co-founder David Siegel, according to The Wall Street Journal. Laura Overdeck is contesting whether the $723 million settlement her husband has offered is fair after a nearly 24-year marriage. Her lawyers estimate the firm's value and seek a cash payment equal to 35% of his stake, or about $2.2 billion. Overdeck testified that "maintaining voting parity with Dr. Siegel is a principal concern," warning that forced liquidation of that much of his stake could shift control of the firm toward Siegel. Judge Bruce Buechler has pressed back on efforts to make Two Sigma governance and financial records public in the divorce proceeding, noting the court is not presiding over a dispute between Overdeck and Siegel.

The Two Sigma rift dates to the firm's founding in 2001, when Overdeck and Siegel, former colleagues at D.E. Shaw, launched the quant manager with about $27 million. Overdeck led the modeling teams that design trading blueprints, while Siegel's engineers built the underlying systems. Under the original operating agreement, the two needed consensus on most decisions. Tensions grew over credit, compensation and succession, and were compounded during the Covid-19 work-from-home period. A 2022 internal proposal, known as the "manifesto," urged Siegel to step aside and was poorly received. By 2023, the firm's SEC annual filing identified the relationship as a material risk and said disagreements affected its ability to retain and attract staff, including senior employees.

Governance has since cycled through repeated changes. In August 2024, Overdeck and Siegel ceded co-CEO roles to proxies Carter Lyons and Scott Hoffman while remaining co-chairmen. Overdeck added himself to the management committee in March 2025, and Hoffman later resigned, citing "ongoing governance challenges since Mr. Overdeck's return," per a firm filing. Siegel designated Seth Platt to succeed Hoffman, but a dispute over Platt's co-CEO status followed, with Platt seeking arbitration in August to be named co-CEO. Siegel has also filed an arbitration claim alleging Overdeck breached fiduciary duty and holds undisclosed conflicts, including Overdeck's hiring of former general counsel Matt Siano as a family office consultant while Siano was in arbitration with the firm.

Client confidence has been tested but not broken. Two Sigma's Absolute Return Enhanced fund gained about 16% through September, and the firm raised roughly $4.5 billion in net new money this year, according to a person familiar with the matter. A Two Sigma spokeswoman said AUM is at a record high and that the firm has been open with investors about the co-founder disagreements. Still, the State of Wisconsin Investment Board, which oversees more than $178 billion, fully redeemed after the rift became public, having held over $1 billion at the end of 2023. Mars Inc.'s pension plan redeemed about a quarter of its roughly $70 million stake by the end of 2024, and gatekeeper Albourne lowered its rating on the firm earlier this year.