Bankroll — Definition | Polymarket Trade
The total capital a trader has allocated to prediction-market trading. It's money set aside for markets only, separate from essential funds. Bankroll management protects against ruin and enables long-term sustainable profits.
In depth
Bankroll is simply the total amount of capital you have decided to use for prediction-market trading. Think of it as a dedicated pot of money—separate from your savings, rent, groceries, or emergency fund—that you've allocated exclusively to placing bets and trading on markets like Polymarket. If you have $5,000 set aside for prediction markets, that $5,000 is your bankroll. The key word here is "set aside": it's money you've consciously earmarked for this purpose, not money you need for everyday living. This distinction is crucial because it frames bankroll as a commitment, not a reckless gamble with funds you can't afford to lose.
The term "bankroll" originates from gambling and gaming culture, where it refers to a player's total capital stack. In poker rooms, sports betting, and casinos, a bankroll is the lifeblood of play—it determines how many hands you can play, how large your bets can be, and critically, how much you can afford to lose before you're forced to stop. In prediction markets like Polymarket, bankroll carries the same weight. Markets are inherently risky: even well-reasoned predictions can be wrong, and prices fluctuate based on thousands of traders' views. A trader without a properly sized bankroll can easily be wiped out by a series of losing trades or a catastrophic adverse price movement. This is why bankroll management has become a cornerstone concept in risk management and professional trading. It's not glamorous, but it's the foundation that separates casual traders from sustainable ones.
On Polymarket, your bankroll determines the universe of trades you can make. If your bankroll is $1,000, you might place ten $100 bets across different markets, or five $200 bets on your highest-conviction predictions. Every trade you make reduces your available bankroll (though wins add back to it). Smart traders think carefully about position sizing—never betting their entire bankroll on a single prediction, even if they're very confident. Instead, they might risk only 2–5% of their bankroll per trade, ensuring that a string of losses doesn't wipe them out entirely. For example, with a $5,000 bankroll and a 2% risk-per-trade rule, you'd risk no more than $100 per bet. This means even if you lose 50 consecutive trades—an unlikely but non-zero scenario—you'd still have money left and the ability to keep trading. On Polymarket's interface, as you place and resolve orders, you'll see your available balance update in real time, reflecting gains and losses against your bankroll.
A frequent mistake traders make is confusing their bankroll with their total wealth. Someone might have $50,000 in savings but allocate only $2,000 as their trading bankroll—and that's perfectly reasonable and responsible. Conversely, a trader might feel wealthy and treat their entire liquid net worth as a bankroll, then face catastrophic losses they can't recover from. Another pitfall is the "gambler's fallacy" of not respecting bankroll limits once they've set them. A trader wins a few trades, feels invincible, and suddenly starts betting 10% or 20% of bankroll per trade instead of the planned 2–3%. This overconfidence leads to ruin. Similarly, traders sometimes don't account for transaction costs, spreads, or slippage—effectively shrinking their bankroll without realizing it. Finally, some traders never separate emotional money from rational capital allocation, leading to "revenge trading" where they try to recoup losses by taking increasingly aggressive bets, which only accelerates losses.
Bankroll is tightly linked to several other critical concepts in prediction-market trading. Position sizing—how much you bet on each individual trade—is derived from your bankroll; you can't size positions rationally without knowing your total capital. Kelly Criterion is a formula some traders use to calculate optimal bet sizes based on bankroll, edge, and probability. Drawdown refers to the peak-to-trough decline in your bankroll during a losing streak; understanding your tolerance for drawdown helps you set appropriate bankroll sizes upfront. Risk of Ruin calculations help traders estimate the probability of losing their entire bankroll based on their edge and typical position sizing. And portfolio theory applies here too: diversifying your bets across multiple markets and categories reduces the variance in your bankroll returns, smoothing out the emotional roller coaster of single-outcome dependency. All of these concepts hinge on having a clearly defined, well-managed bankroll.
Example
Suppose you're predicting the 2026 US midterm election outcomes. You've set aside a $10,000 bankroll for this election cycle. You place a $300 bet (3% of bankroll) on 'Democrats gain Senate seats' at 55¢, a $250 bet on 'Republicans control the House' at 62¢, and a $400 bet on 'Inflation remains above 3%' at 48¢. Each trade commits only a small portion of your bankroll, so even if all three predictions miss, you've lost $950—painful, but still have $9,050 to continue trading through November.