Jeffrey 'Jeff' S. Yass is an American businessman, the self-made billionaire Co-founder and Managing Director of Susquehanna International Group (SIG), one of the largest and most successful quantitative trading firms in the world. Born in Queens, New York, in 1958, his career is defined by his mastery of mathematics, game theory, and probabilistic thinking.

Yass graduated with a degree in Mathematics from SUNY Binghampton. His philosophy centers on the conviction that financial trading is a game of odds that can be solved with mathematical and statistical analysis. His early career began as a professional gambler, leveraging his mathematical skills to play poker and bet at racetracks in Las Vegas, an experience that laid the foundation for his trading success.

• Susquehanna International Group (SIG) (Co-founder & Managing Director): The core private asset, one of the largest quantitative trading firms in the world, specializing in options, convertible bonds, and derivatives.
• Gambling Career: He worked as a professional gambler (poker, horse racing), applying game theory and probability to betting.
• Political Focus: He is a major political donor to the Republican Party (supporting Donald Trump and conservative causes) and is one of the largest U.S. shareholders of TikTok (China).
• Investment Strategy: His philosophy: always bet against the mark (a professional poker mantra applied to the options market).

Jeff Yass, with his college friends, pooled their money to become professional poker players in Las Vegas. He returned to New York and, in 1987, co-founded Susquehanna International Group (SIG). His strategic genius was applying his quantitative skills and game theory to the options and derivatives markets, institutionalizing trading with proprietary algorithms. SIG made $30 million on puts during the October 1987 market crash, cementing its early reputation.

His structural contribution is tied to the successful monetization of statistical arbitrage and liquidity provision in complex financial markets. He is also a major investor in TikTok (which he invested in early) and a key figure in U.S. political spending, making him one of the most influential men on Wall Street. His wealth is tied to the colossal, long-term, superior returns generated by SIG's quantitative trading models.

Jeff Yass's social impact is structural, stemming from SIG's role as a major provider of market liquidity and efficiency in the global derivatives markets. His political spending is a massive structural contribution to conservative political causes and policy debates (particularly over school choice).

His personal philanthropy supports various educational and community initiatives. His career is a testament to the profitability of disciplined quantitative analysis and leveraging the principles of game theory for financial success.

Jeff Yass maintains the professional, pragmatic style of a financial executive. His attire is consistently formal and high-quality, favoring tailored suits. His aesthetic reflects stability and immense financial authority, typical of a leader in the secretive world of quantitative trading.

Residing in Philadelphia, Pennsylvania, his luxury is the immense security and financial reward derived from his multi-billion dollar fortune. His life is dedicated to quantitative finance, investment strategy, and his profound commitment to Republican politics and conservative policy.