Long before trading interviews included market-making games, there was a boxed card game called Pit. It was published in the early 1900s and modelled on the commodity trading floor: players shout across a table, swap cards blind, and race to corner a market. It is loud, it is fast, and it teaches several things that trading firms now test candidates on directly.
This guide is about what the game teaches, not how to win a family game night. QuantPit is independent and has no connection to any publisher of Pit; edition details differ, so treat the rules described here as the shape of the game rather than a rulebook.
How the game works
Each player is dealt a hand of commodity cards, wheat, corn, barley and so on, with the deck holding an equal number of each. The goal is to corner a commodity: to hold every card of a single type, and to announce it before anyone else corners theirs.
Trading is the whole game and it happens through one narrow channel. You may only offer a number of cards, not their identity. You hold up two cards and shout "two, two, two" until someone else with two to give takes the trade, and the swap happens sight unseen. Everyone trades at once, continuously, with no turns.
Some editions add a Bull and a Bear card, which reward or punish the hand holding them at the moment somebody corners. They inject exactly the tail risk that makes an otherwise arithmetic game feel like trading.
What it actually teaches
1. A quantity is a signal, whether or not you mean it to be
You cannot say what you are trading, only how much. Yet the numbers leak information constantly. A player who has been shouting "one, one, one" for a minute is close to a corner and shedding a final stray card. A player suddenly offering three when they were offering one has just been broken up by a trade that went against them.
This is the game's central lesson and it is the same one that governs order flow: the size and pattern of what someone is willing to trade tells you about what they hold. Traders read size for the same reason Pit players count shouts. Our market-making question set works through the formal version of this, where quoted size and fill patterns reveal a counterparty's position.
2. Every fill is information about the person who took it
When your "two" gets taken instantly, ask why. The player across the table wanted two cards badly enough to move before anyone else did, which usually means those two cards complete something for them. You just helped them and learned it a second too late.
That is adverse selection in its purest form: the trades that fill fastest are the ones the other side wanted most, and the ones that sit unfilled are the ones nobody wants. A market maker who is delighted by a fast fill has not yet learned the lesson Pit teaches in ten seconds. The Kelly criterion guide covers the sizing consequence, and the timing consequence is what our Market Maker game simulates against bots who know more than you do.
3. Speed is a real edge, and it degrades your judgement
Pit is played in a shouting match. In that environment, players make trades they would never make on reflection, because the alternative is standing still while everyone else trades. Recognising when speed is genuinely valuable and when it is just noise pressure is a skill trading firms select for hard, and it is why so many interview formats put a clock on you. It is also why the 80 in 8 benchmark is a real test of temperament rather than only arithmetic: accuracy under a clock is a different skill from accuracy.
4. Cornering is a lesson in convexity
Holding seven of nine wheat cards is worth almost nothing. Holding nine is worth the round. The payoff is nothing like linear in progress, so the correct strategy near the end is completely different from the correct strategy at the start: early on you trade freely to discover what is available, and late you refuse trades that would break up a near-complete hand even when they look fair.
Positions with convex payoffs, options being the standard example, behave the same way. What looks like the same trade is right early and wrong late, purely because of where you already are. Our options topic set formalises this.
5. There is no market maker, and it shows
Notice what Pit lacks: nobody is obliged to quote both sides. Every player is trying to accumulate, nobody is trying to intermediate, and the result is a market where trades are slow to find their counterparty and information is discovered by shouting rather than by price.
That absence is the best argument for what market makers actually do. A real venue has someone standing ready to buy and sell continuously, which is why you can trade instantly at a known price instead of yelling "two" for a minute. Candidates who can explain that difference clearly, that liquidity is a service with a cost and a risk, tend to do well in interviews that ask "why do market makers make money?"
If you want to play the trading version
The instincts above transfer directly to interview trading games, where the format is usually cleaner: you quote a two-sided price on something uncertain and the interviewer trades against you. Our Market Maker game runs that version against bots with noisy private estimates, so quoting too tight gets you picked off and quoting too wide gets you no fills.
For the interview context around it, the Jane Street process guide covers how market-making games appear in final rounds, and the firm guides note which firms lean on trading games most heavily.
FAQ
What is the Pit card game?
Pit is a commodity trading card game published in the early 1900s and inspired by open outcry exchanges. Players trade cards by shouting quantities rather than naming commodities, and the goal is to corner a commodity by collecting all of its cards.
How is Pit related to real trading?
It reproduces three features of a real floor: continuous simultaneous trading rather than turns, information leaking through the size people are willing to trade, and a fast payoff to being first. It lacks a market maker, which is precisely why trades in it are hard to complete.
Do trading firms use Pit in interviews?
Not typically as the boxed game. Firms tend to use their own market-making exercises where candidates quote two-sided prices, and some publish their own games. The transferable skill is reading flow and pricing under uncertainty rather than the specific game.
What is the best way to practise these skills?
Play a market-making simulation where you quote prices and face informed counterparties, then narrate your reasoning after each fill: what your fair value was, why you widened, and whether the fill was good news or bad. That reflection is what turns play into interview-ready judgement.