The Story of Susquehanna International Group (SIG): Probability and Poker

Founded in 1987 with $30k, SIG applied game theory to options trading at a global scale. Discover the firm built on poker discipline.

SIG was founded in 1987 by Jeff Yass and four college friends in Philadelphia. They each put in $30,000 to start trading options. The founders played poker seriously and applied the same logic to trading: probability, expected value, and risk control.

SIG became known for options market making, where math skills and quick decisions made the difference. Through the 1990s and 2000s, SIG expanded into equities, ETFs, commodities, and fixed income. The firm also grew internationally, opening offices in Dublin, Sydney, and Shanghai.

New hires were taught probability, statistics, and game theory, with poker used as a teaching tool to sharpen decision-making. SIG invested heavily in trading systems and data infrastructure to improve speed and precision.

Today, SIG is one of the largest privately held trading firms in the world. It trades tens of thousands of products every day across global markets. SIG showed how probability and mathematics could be applied directly to markets at scale.