Prediction Markets Explained: How Event Contracts Work

A contract trading at 38 cents on a prediction market is not an arbitrary quote—it is the crowd saying an outcome has a 38% chance of happening.

Platforms like Kalshi and Polymarket have turned news, economic reports, and world events into liquid financial markets. Instead of buying company shares or betting against a casino, you buy binary shares that resolve to either $1.00 or $0.00.

Before putting money into these platforms, you need to understand the mechanics. They look simple on the surface, but the math, execution fees, and settlement rules operate under very different incentives than traditional stock derivatives or sports betting apps. (Note: This breakdown is strictly educational and is neither financial nor gambling advice.)

The core mechanic: cents become implied probabilities

Every event contract asks a specific yes-or-no question: Will the Federal Reserve cut interest rates at the next meeting? or Will a specific city exceed 90 degrees on Tuesday?

Every contract trades between $0.01 and $0.99. When the event concludes, the exchange resolves the question. If the answer is Yes, every Yes share pays out $1.00 and No shares become $0.00. If the answer is No, No shares get the full $1.00 payout and Yes shares expire worthless.

Here is how the pricing translates into numbers:

• If you buy 100 Yes contracts at $0.38, you pay $38.00 upfront.
• If the event happens, you receive $100.00 (a $62.00 profit before fees).
• If the event fails, your position expires at $0.00 (you lose your original $38.00).

Because the sum of the Yes and No price always equals $1.00 in a balanced book, the share price acts as a live, crowd-sourced probability meter. As breaking news hits, traders buy or sell shares, moving the price to reflect new information in real time.

How event contracts differ from stock options

If you already trade equity derivatives, event contracts look familiar because they share an expiration date, but the payoff structure is completely different.

When we covered options explained for complete beginners, we saw that traditional call and put contracts track an underlying share price. If a stock moves $10 past your strike price, your option gains open-ended intrinsic value. Stock options also carry complex pricing math—known as the Greeks—which measure volatility swings, strike distance, and continuous time decay.

Event contracts drop all of that complexity. They are fixed binary bets. It does not matter whether an inflation report misses expectations by 0.1% or 5.0%—the contract only checks whether the stated condition was met. You do not have to calculate delta or worry about margin calls, because event positions are 100% cash-funded up front. Your maximum loss is always limited to the exact dollar amount you paid to enter.

You are trading against other people, not the house

Traditional sportsbooks and prediction markets may cover similar topics, but their business models are opposites.

A sportsbook acts as the counterparty—the house. They build a hefty profit margin (the "vig") into the odds, usually running anywhere from 4% to 10% or more. If you become consistently profitable, a standard retail sportsbook will routinely limit your maximum bet size or shut down your account to protect their bottom line. You also cannot easily trade out of a bad sports bet once the match begins unless you accept terrible cash-out terms.

Prediction markets run on a central limit order book (CLOB), similar to the stock market. The exchange does not take the other side of your trade; they simply match buyers with sellers.

This setup creates three major differences:

1. You can exit anytime: If you buy a contract at 30 cents and good news drives the price to 70 cents, you can sell your shares on the open market immediately and lock in your gain. You do not have to wait for the final outcome.
2. No winning bans: Because the platform earns money on transaction volume rather than your losses, profitable traders are not banned or throttled.
3. Lower overhead: Spreads and exchange fees are generally far tighter than casino vig.

For a deeper dive into the regulatory framing around this, see our breakdown on event contracts and probability pricing.

Maker-taker fees and hidden liquidity costs

Trading prediction markets is cheap compared to sportsbooks, but costs still eat into returns if you use lazy order types.

Most modern prediction platforms use a maker-taker fee model. When you place a limit order that sits on the order book waiting for someone else to match it, you are a maker adding liquidity. Makers typically pay zero percent in trading fees and can even earn fee rebates. When you use a market order to buy immediately from an existing quote, you are a taker, and you pay a variable fee that scales based on the contract price (often peaking near the 50-cent mark where trading is heaviest).

The bigger trap is thin liquidity. On major national markets, thousands of contracts sit on both sides. On smaller, niche markets—like local weather benchmarks or specific regulatory rulings—the gap between the highest buy order and lowest sell order might be 6 to 10 cents wide. If you buy at 45 cents and want to sell instantly on a thin book, the best buyer might only be offering 38 cents. That bid-ask spread is an immediate drag on your capital.

Settlement wording is where trades quietly blow up

Here is the biggest honesty beat in prediction markets: the primary risk is rarely market direction—it is resolution dispute.

Every event contract contains strict, legalistic resolution rules detailing the exact data source used to determine the outcome. If you do not read the rulebook before trading, you can easily find yourself holding a losing ticket on an event you thought you won.

For example, if a player is listed on an injury report and sits out a game, one platform's rules might cancel the contract and refund all money, while another platform's rules might treat the absence as an active "No" that settles at zero.

Similarly, regulatory structure changes how your money is held:

• Regulated exchanges (like Kalshi): Operate under Commodity Futures Trading Commission (CFTC) oversight in the United States, settle in standard US dollars via bank transfers, and require standard identity verification.
• Crypto-native platforms (like Polymarket): Historically operate on blockchain networks (like Polygon) settled in stablecoins like USDC, relying on decentralized resolution oracle protocols like UMA alongside emerging regulated apps.

If you decide to test these platforms, keep your trade sizes modest and check our guide on how position sizing protects your account to avoid overcommitting to uncertain outcomes.

The one-minute evaluation checklist

Before taking a position in any binary event contract, run through these four practical checks:

1. Read the resolution source: Confirm the exact agency, API, or official report that determines the final Yes or No. Never guess based solely on the market's title.
2. Check the bid-ask spread: If the gap between the bid and ask is wider than 2 or 3 cents, place a resting limit order instead of hitting market buy.
3. Calculate your true breakeven: Remember that paying 75 cents for a contract means you are risking 75 cents to make 25 cents. You need a win rate higher than 75% to make that trade mathematically positive over time.
4. Plan your exit: Decide upfront whether you intend to hold through the final resolution or sell early if the probability swings 15 to 20 cents in your favor.