What are prediction markets? A plain-English introduction

The basic idea

A prediction market is an exchange where people trade contracts tied to the outcome of a future event: Will the Fed cut rates in September? Will this candidate win the election? Will inflation exceed 3% this year? Each contract pays a fixed amount — typically $1 — if the event happens, and nothing if it doesn't.

Because the payout is fixed, the price of the contract becomes a probability. If a "YES" contract on a rate cut trades at 62 cents, the market is collectively saying there is roughly a 62% chance of a cut. If you think the true probability is higher, you buy; if you think it's lower, you sell. The price settles where buyers and sellers balance — a live, constantly updated estimate of how likely the event is.

How a trade actually works

Suppose a contract on "Will US CPI exceed 3% in December?" trades at 41¢. You believe the answer is more likely than that, so you buy 100 YES contracts for $41. Three outcomes are possible:

• The event happens. Each contract settles at $1. Your $41 becomes $100 — a $59 profit before any fees.
• The event doesn't happen. The contracts settle at $0 and you lose your $41 stake entirely.
• You exit early. Prices move continuously as news arrives. If the price rises to 55¢ next month, you can sell and take the $14 gain without waiting for resolution.

Every market needs a precise resolution rule — the exact data source and criteria that determine the outcome. Serious platforms publish these rules up front, and reading them carefully is the single most important habit for new traders: many "surprise" losses come from misreading what a market actually resolves on, not from bad forecasts.

Why market prices tend to be good forecasts

Prediction markets aggregate information in a way polls and pundits struggle to match. Anyone who believes the price is wrong can profit by correcting it — so people with genuine information or better models have a direct incentive to trade, and the price absorbs what they know. Traders who are consistently wrong lose money and fade; traders who are right gain capital and influence.

A long line of research — from the University of Iowa's experimental electronic markets that have run since 1988, through modern studies of election and economic markets — has found well-designed prediction markets to be at least competitive with, and often better than, expert forecasts and polling averages. They are not oracles: they have been wrong on notable occasions, and thin markets with few traders can stay mispriced for a while. But as a running summary of the best available public information, they are hard to beat.

Where prediction markets trade

Two platforms define the category in 2026. Kalshi is a CFTC-regulated US exchange where contracts trade in dollars, with the customer protections you would expect from a regulated venue. Polymarket is the largest platform by volume, settling in the USDC stablecoin, with the deepest order books on major world events and US access restored through a regulated structure. They differ meaningfully in fees, funding and market coverage — our head-to-head comparison covers the details.

The same event is often listed on both venues, and because each runs its own order book, prices can differ by a few cents. Comparing those prices — and understanding when a gap is meaningful versus an artifact of fees and liquidity — is exactly what this site is being built to do.

The risks, plainly

Prediction markets are a form of trading, and the risks are real:

• Total loss per position. A contract that resolves against you is worth zero. There is no partial credit.
• Liquidity risk. In thin markets you may be unable to exit at a fair price, or at all, before resolution.
• Resolution risk. Ambiguous wording or disputed outcomes occasionally happen, particularly on platforms using decentralized oracle mechanisms.
• Jurisdiction and eligibility. Access rules differ by country and state, and they change. Verify your eligibility with the platform, not with third-party sites.
• Behavioral risk. Fast markets on exciting events invite overtrading. A probability you can trade is still a wager if you treat it like one.

Getting started sensibly

If you decide to try prediction markets, the boring advice is the good advice. Start with money you can lose without consequence. Read the resolution rules of every market you touch. Prefer liquid markets with tight spreads while learning. Understand each platform's fees — our platform comparison is a starting point — and treat your early trades as tuition, not income.

Above all, remember what the price is: the market's probability, not a promise. A contract at 90¢ still loses one time in ten — and the market is perfectly happy to let that time be yours.