Yass is the founder of Susquehanna International Group, a proprietary trading firm. The Bala Cynwyd, Pennsylvania-based company makes markets in financial products and asset classes with a focus on derivatives. It also invests in private equity and venture capital. Yass also has a minority stake in ByteDance, the developer of TikTok.
Yass's fortune is derived from Susquehanna International Group, a market-making and proprietary trading firm he co-founded.
Yass is credited with 51% of the firm, based on a March 2026 filing indicating Philadelphia Trading Inc owns a stake of between 50-75%. Yass is the sole principal of Philadelphia Trading Inc., according to Florida filings.
Susquehanna's 2025 revenue is calculated at $22.1 billion based on having about 3,500 employees and the average revenue-to-employee multiple of a basket of other trading firms. Its calculated to have the same Ebitda margin as Jane Street in 2025, roughly 67%, and the same level of debt-to-employee. The business is valued using the average enterprise value-to-Sales, enterprise-to-value-to-Ebitda and price-to-earnings multiples of publicly-traded peers.
Susquehanna also owns about 15% of ByteDance based on an October 2020 Wall Street Journal report and adjustments for dilution. Yass is credited with half that stake based on his Susquehanna ownership.
It's valued at $435 billion in this analysis based on the average of investors BlackRock, T. Rowe and Fidelity valuations as of December 2025, as well as a $420 billion stake sale in November 2025, according to a Bloomberg News report.
Bytedance completed a sale of TikTok US in January 2026. Susquehanna owned about a quarter of the roughly 60% stake in Bytedance owned by foreign investors, and its credited with the same percentage of the 30% stake in TikTok US owned by existing Bytedance investors following the deal. Half of that, or about 3.7%, is credited to Yass. Its valued using the sale value of $14 billion.
A June 21, 2022 report in Propublica based on leaked tax returns detailed more than $11 billion in income Yass collected between 2009 and 2018. That income is used to calculate the value of his other assets, including adjustments for taxes and market performance.
A spokesman for Yass declined to comment on the billionaire's net worth in March 2026.
Jeff Yass was born and raised in New York City, the son of two accountants. Encouraged by his father, he took an interest in stocks and gambling at an early age. His first stock purchase was food company Campbell after enjoying one of their TV dinners.
He attended college at the State University of New York Binghamton. While there he frequently played poker and bet on horse races, and bonded with a group of friends with similar interests who he'd eventually go on to found Susquehanna with. His thesis concerned whether options added value to society.
After graduating he moved to Las Vegas to become a professional gambler, but soon decided to move to Philadelphia to become an options trader. He was supported by Israel Englander, the founder of Millennium Management, who helped him buy a seat on the Philadelphia Stock Exchange.
In 1987 he founded Susquehanna International Group along with five of his college friends. The firm began as an options market-maker, but now trades in a wide variety of financial asset classes, as well as offering sports and political betting derivatives. It also has venture capital and private equity groups that invest the firm's capital.