Most trading firms teach you their models. Susquehanna teaches you Texas Hold'em. Every new hire goes through structured poker training, plays daily during onboarding, and the firm runs a global No Limit tournament every year with a seat at the final table on the line. This is not team-building. It is the curriculum.

SIG was founded in 1987 by Jeff Yass and a group of college friends who traded on the floor of the Philadelphia Stock Exchange and happened to be serious gamblers and mathematicians. Yass's view is that markets are a probability game, not a prediction game: you cannot control the cards or the tape, only how you size risk and when you act. As he put it, poker is not a game, it is a training ground for traders who want to survive uncertainty. The whole firm is built on that one transfer.

The skill is the same skill

Poker and options market-making run on identical machinery: incomplete information, expected-value reasoning, opponent modeling, disciplined bet sizing, and emotional control when you are losing. SIG made the analogy literal. It employs World Series of Poker bracelet winners Bill Chen and Jerrod Ankenman, co-authors of The Mathematics of Poker, as quantitative researchers. The training program, widely rated among the best in the industry, runs several weeks of options theory and game theory with poker threaded through all of it.

There is a lineage point that ties this whole series together. Those Jane Street founders who left to build the anarchist commune in OCaml left from here. The poker table at SIG is upstream of two of the most distinctive firms in the business. Culture, like talent, has a family tree, and a lot of branches trace back to one trading floor outside Philadelphia.

The recruiter's read: SIG figured out that the unit of talent worth selecting for is not knowledge, it is calibrated decision-making under uncertainty, and that poker is the cheapest high-fidelity test of it ever invented. You cannot fake EV thinking at a table for long. It is a live interview that runs for hours and that the candidate enjoys. Every firm screens for raw intelligence. SIG screens for temperament, which is the part that actually breaks people on a trading desk.