What Are Prediction Markets?

A prediction market is a market where people trade on the outcome of future events. Instead of buying a share of a company, you buy a share in an answer, such as "Yes, this will happen" or "No, it will not." When the event is decided, every correct share pays out a fixed amount, usually $1, and every incorrect share pays nothing. Because of that simple payout, the price of a share can be read as the crowd's estimate of how likely the outcome is.

How a prediction market works#

Take a question like "Will Bitcoin close above $100,000 on Friday?" The market offers two kinds of shares:

• Yes shares pay $1 if the answer turns out to be yes.
• No shares pay $1 if the answer turns out to be no.

Before the event, both trade between $0 and $1. If Yes trades at 62¢, No trades at roughly 38¢, because exactly one of them will be worth $1 at the end. Together, a Yes and a No share are always worth $1 at settlement.

Prices as probabilities#

If a Yes share costs 62¢ and pays $1 when right, buying it only makes sense if you think the true chance is above 62%. If many traders thought the chance was 80%, they would keep buying until the price rose toward 80¢. If they thought it was 40%, they would sell until it fell. So the price settles around the level where buyers and sellers disagree evenly, which is the market's implied probability.

That reading has limits. The price includes a Bid-Ask Spread, thin markets can be moved by a single large trader, and people tend to overpay for long shots. Read Reading Odds as Probabilities for how to adjust for those effects.

You do not have to wait for the end#

Shares trade continuously, so you can sell before the event is decided. If you bought Yes at 62¢ and new information pushes the price to 75¢, you can sell and lock in 13¢ a share without waiting. This makes prediction markets behave like any other market: prices react to news, and traders can profit from changes in the crowd's opinion as well as from the final outcome.

How markets get settled#

Every market has written rules that say exactly how the outcome is decided and from which source. This is called resolution. Good rules name a specific data source and time, for example a particular price feed at 4:00 p.m. Eastern time. Before trading any market, read its rules. Many disputes happen because traders assumed a question meant something it did not.

On Polymarket, the largest crypto based prediction market, most markets are resolved through UMA's optimistic oracle, where a proposed answer can be challenged before it becomes final. Its short term crypto up or down markets settle automatically on price data from Chainlink. See How Polymarket Works and Price to Beat and How Rounds Settle.

What people trade#

Short crypto markets are the fastest moving. On Polymarket, Bitcoin and other major coins have rolling rounds that ask whether the price will finish a 5 minute or 15 minute window above where it started. These work very differently from long dated political markets and are covered in Up or Down Markets Explained.

A short history#

Prediction markets are older than the internet. The University of Iowa has run the Iowa Electronic Markets for research since 1988, letting people trade small amounts on elections. Studies of these and similar markets found that their prices were often as accurate as, or more accurate than, polls. Crypto based platforms later made it possible to run large global markets with stablecoins, and regulated exchanges in the United States now list event contracts under oversight from the CFTC. See the background on prediction markets.

The risks#

• You can lose your whole stake on each share. A share bought at 62¢ goes to zero if you are wrong.
• Resolution risk. Unclear rules or a disputed outcome can settle a market differently from what you expected.
• Liquidity. Small markets can have wide spreads and few buyers when you want to sell.
• Platform and legal risk. Crypto platforms carry smart contract and custody risk, and the rules on who may use which platform differ by country and change over time. Check what is allowed where you live.
• Behavior. Fast markets, especially 5 minute rounds, can feel like a game and encourage overtrading. The same discipline you would use in any market applies; see Overtrading and Position Sizing.

Getting started sensibly#

1. Learn how prices relate to probabilities and Expected Value.
2. Pick one market type and learn its rules and data source completely.
3. Start very small, and track your results against the prices you paid.
4. Watch how prices react to information before you risk money.

If you want to watch Polymarket's short Bitcoin rounds alongside the live price they settle on, the TradeLabs AI chart shows each round, its price to beat and the market's odds as they move.

Next, see exactly how the largest platform works in How Polymarket Works, then learn to judge odds in Reading Odds as Probabilities.

Frequently asked questions#

How do you make money on a prediction market?#

You buy shares in an outcome at a price below $1. If the outcome happens, each share pays $1. You can also sell before the event if the price rises. You profit over time only if you are right more often than the prices you pay imply.

Are prediction market prices accurate?#

Often they are reasonably accurate, and research on markets like the Iowa Electronic Markets found them competitive with polls. They can still be wrong, especially in thin markets or when traders overpay for unlikely outcomes.

What happens if a market is resolved incorrectly?#

Each platform has its own dispute process. On Polymarket, most markets resolve through UMA's optimistic oracle, where a proposed outcome can be challenged before it becomes final. Always read a market's rules before trading it.

Is Polymarket legal?#

It depends on where you live, and the rules have changed over time. Check the platform's current terms and your local laws before using any prediction market.

Sources#

• Wikipedia, Prediction market
• Wikipedia, Iowa Electronic Markets
• Polymarket, Documentation
• U.S. Commodity Futures Trading Commission, Learn and protect