Jeff Yass: The Poker Player Who Turned Probability Into a Trading Empire

Last reviewed: August 2026. Sources: Jack Schwager’s The New Market Wizards, Forbes, and public records of Susquehanna International Group.

Most traders want to know if a trade is good. Jeff Yass trained himself to ask a colder question first: at this table, am I the smart money or am I the mark? If he could not answer confidently that he was the one with the edge, he did not play. That single habit — borrowed straight from the poker table — grew into Susquehanna International Group, a firm that at times has handled close to a quarter of all options trades in the United States.

Yass is the Market Wizard who insists that trading, poker, and betting on horses are the same activity wearing different clothes. All three are repeated decisions under uncertainty, where the only durable edge is being better at estimating probabilities than the person on the other side of the bet. To understand him is to understand why the size of your edge, not the drama of any single trade, is what actually makes money.

From a dorm-room card game to a global trading firm

Yass grew up in Queens and went to SUNY Binghamton to study mathematics and economics. His real education happened alongside the coursework, at the poker table and the racetrack, with a crowd of science-minded friends who treated gambling not as vice but as a laboratory for probability and game theory. Yass came away convinced that the same prism — edge, odds, expected value — could be pointed at almost anything.

He turned professional, grinding poker and handicapping horses to build a stake. His break into markets came through Israel Englander, later the founder of Millennium Management, who in 1981 offered Yass a seat on the Philadelphia Stock Exchange in exchange for a share of the profits. Yass took the gambling instincts he had sharpened on cards and horses and pointed them at options during the booming markets of the 1980s.

In 1987 he and five friends founded Susquehanna, naming it after the river near their new home. The timing looked catastrophic — the market crashed months later on Black Monday — but the firm had a position that paid out if stocks fell, and it was one of the few that made money in the crash. From there Susquehanna grew into a global powerhouse in options and market making, trading across stocks, ETFs, futures and crypto in dozens of countries, and it did the whole thing without ever taking a dollar of outside capital.

The method: markets are a game, and edge is everything

Yass’s approach rests on a handful of ideas that sound simple and take a career to master.

Think in probabilities, not predictions. Yass does not try to know what a stock will do. He tries to price the range of things it might do more accurately than the rest of the market, then trades the gap between his estimate and the quoted price. An option, to him, is just a bet with a calculable expected value; the job is to buy the ones priced too cheaply and sell the ones priced too dear, thousands of times over.

Only bet when you have the edge. His most famous rule is the poker player’s rule: make sure you are trading against someone less informed than you are. If he cannot identify why he is the smarter money in a given trade, he assumes he is the mark and walks away. Arrogance about an edge you do not really have is, in his framing, the fastest way to get crushed.

Size the bet to the edge. Having an edge is not enough; you have to bet the right amount. Too small and you leave money on the table; too large and a run of bad luck ends the game. Yass built Susquehanna around scaling position size to the strength of the edge and the risk of ruin — the same discipline that separates winning poker players from reckless ones.

Hire and train for decision-making. Susquehanna became famous for teaching new traders poker as a core part of the curriculum, watching how recruits handled uncertainty, spotting the ones who anchored to irrelevant numbers or chased losses. A reckless poker player, Yass found, made a reckless trader. The card table was a hiring filter.

The defining lesson: separate the decision from the outcome

The deepest thing Yass teaches is a mental split most traders never make: a good decision and a good outcome are not the same thing. In poker and in markets, you can make the correct, positive-expected-value bet and still lose the hand; you can make a terrible bet and get lucky. Over one trade, luck dominates. Over ten thousand, edge does.

This is why Yass is untroubled by individual losing trades and deeply troubled by sloppy thinking that happened to win. He grades the quality of the decision and the size of the edge, then lets the law of large numbers do the rest. It is the same lesson William Eckhardt and Larry Hite preach from the systematic side, arrived at through a deck of cards.

Where the Mind · Method · Money framework meets Yass

Method is his probability engine: pricing uncertainty better than the market and trading the difference. It is unglamorous, repeatable, and utterly unconcerned with narrative or prediction — a machine for harvesting small, well-understood edges at enormous scale.

Money is where his poker roots show most clearly. Bet sizing relative to edge and risk of ruin is the whole ballgame. Yass’s insistence that you can have a real edge and still go broke by betting too big is position-sizing wisdom that every retail trader needs and almost none applies.

Mind is the discipline to ask “am I the sucker?” honestly, to act on probabilities rather than hope, and to separate the quality of a decision from the luck of its result. That emotional detachment — treating each trade as one hand in a very long game — is the psychological core of everything he built.

The honest counterweight

Yass is a genuine great, but very little of what made him rich is available to a retail trader, and that needs saying plainly.

Susquehanna’s edge is structural and institutional. It comes from market-making infrastructure, speed, scale, and seeing vast streams of order flow — advantages a person at home simply does not have. When the firm captures the spread on a quarter of America’s options trades, it is not making one brilliant call; it is running an industrial process that profits from volume most of us cannot touch. You can admire the philosophy without imagining you can copy the business.

His firm is also famously secretive, and much of the recent public attention on Yass has centred on his enormous political donations and investment stakes rather than his trading, which sits outside the scope of a trading profile but is worth acknowledging honestly rather than airbrushing. And the poker-as-training story, while real, can be romanticised: for every gambler who becomes a probability master, many more mistake recklessness for edge and lose. The lesson is the discipline, not the dice.

Finally, “only bet when you have the edge” is easy to say and brutally hard to live. The entire difficulty of trading is honestly assessing whether you actually have an edge — and most people who think they do are the very marks Yass built a fortune trading against.

What to actually take from Jeff Yass

You cannot build Susquehanna, but you can steal its mindset. Three ideas transfer directly.

First, before every trade, ask who is on the other side and why you are the smarter money. If you have no honest answer, that is your signal to pass. Refusing to play when you have no edge is itself a winning strategy.

Second, size to your edge, not your excitement. A real edge bet too large can still ruin you; the amount you risk matters as much as whether you are right. Treat position sizing as a core skill, not an afterthought.

Third, judge decisions, not outcomes. Track whether your process was sound and your edge real, and let results play out over a long series of trades. One loss on a good decision is a cost of doing business; one win on a bad decision is a trap.

Frequently asked questions

Who is Jeff Yass?
Jeff Yass is an American options trader and co-founder of Susquehanna International Group, one of the largest options market-making firms in the world. A former professional poker and horse-racing gambler, he was profiled in Jack Schwager’s The New Market Wizards for applying probability and game theory to markets.

What is Susquehanna International Group?
The Philadelphia-area trading firm Yass co-founded with five friends in 1987. It is among the largest options traders and market makers in the United States, active in stocks, ETFs, futures and crypto globally, and it also invests in early-stage companies — most famously an early stake in ByteDance, TikTok’s parent.

What is Yass’s core trading philosophy?
That trading, poker and betting are the same discipline: repeated decisions under uncertainty. The edge comes from estimating probabilities better than your opponent, only betting when you genuinely have that edge, and sizing each bet to the strength of the edge and the risk of ruin.

What is the “am I the sucker?” rule?
Yass’s principle that you should only trade when you are confident you are the more informed party. If you cannot say why you have an edge over the other side, you should assume you are the one being taken advantage of, and not trade.

How did poker shape his trading?
Yass views well-played poker as pure probabilistic decision-making, not gambling. Susquehanna famously trains new traders using poker to teach bet sizing, edge, and emotional control, and to filter out recruits who make reckless decisions under uncertainty.

Can a retail trader copy Jeff Yass?
Not the business. Susquehanna’s returns come from market-making scale, speed and order flow that individuals cannot access. What does transfer is the mindset: only bet with an edge, size to that edge, and judge your decisions rather than single outcomes.

Which book features Jeff Yass?
The New Market Wizards (Jack Schwager, 1992), in the chapter “The Mathematics of Strategy.”

Continue learning

• Edward Thorp — the blackjack card counter who, like Yass, turned gambling math into a market edge.
• Jim Simons — the mathematician who built the ultimate probability machine at Renaissance.
• Ken Griffin — the other giant whose empire runs on options market making and order flow.
• William Eckhardt — the mathematician who reached the same conclusion about edge and bet size from the systematic side.
• Market Wizards (book review) — our full breakdown of the Schwager series Yass appears in.
• The Mind · Method · Money framework — the lens we use to read every trader on this site.