How prediction markets work

Everything you need to read a market page on this site, in about five minutes.

What is a prediction market?

A prediction market lists a question with a clear answer, like “Will Bill 214 pass the Senate by December 31?” You can buy a contract that pays $1 if the answer is Yes, or one that pays $1 if the answer is No. When the question is settled, the winning side gets $1 per contract and the losing side gets nothing.

Reading the price

Prices are shown in cents, between 0¢ and 100¢. Because a contract pays $1, the price works as the market’s rough estimate of the chance something happens.

It is an estimate, not a fact. Prices can be wrong, especially in small markets with few traders.

Buying Yes or No

Yes and No prices add up to about 100¢. If Yes is 63¢, No is about 37¢. The small gap between the buying and selling price is called the spread, and it is part of your cost.

How a market resolves

Every market has written rules: what exactly counts as Yes, which source decides, and the deadline. Two markets that sound the same can resolve differently because of one word. On every market page we explain the rules in plain English, but always read the original rules on the venue before you trade.

Why prices jump

Prices move when new information arrives: a vote, an injury, a poll, an official statement. They can also move when one trader places a very large order in a market with few buyers and sellers. That is why every wave on this site carries a label: confirmed cause, likely cause, or no news found.

Kalshi and Polymarket

Kalshi is an exchange regulated in the United States. Polymarket runs an international platform and a separate regulated platform for the US. They often list the same question at slightly different prices, which is why market pages here show both. Which one you can use depends on where you live.

Risks to know before you trade