Polymarket
A prediction market: people trade on the outcome of real events, and the price of a "Yes" share reads as the crowd's probability that it happens.
01 · Introduction
What Polymarket is
Polymarket is a prediction market: a site where people buy and sell shares in questions about the future, such as "Will it rain in London tomorrow?" or "Will this bill pass by June?"
Every question (a market) has outcome shares, usually Yes and No. A share pays $1 if its outcome happens and $0 if it doesn't. So the price tells you what traders think:
- Yes trading at $0.30 means the market puts the chance at roughly 30%.
- If you think the real chance is higher, buying Yes is a bet that you are right.
Words you will see:
- Event: a group of related markets (an election with one market per candidate).
- Volume / liquidity: how much has been traded, and how much is waiting in orders. More of both means the price is harder to move and more meaningful.
- Order book: the list of buy and sell offers. The gap between the best buy and best sell is the spread.
- Resolution: when the outcome is decided, according to the rules written on each market.
Reading the markets is free: the website and the data interface need no account, no wallet and no payment. Trading uses a US-dollar stablecoin on the Polygon blockchain, through your own account.
02 · When to use it
When it is useful
- As an information source. The odds on elections and politics, stocks and crypto prices, and sports results are often remarkably accurate: people who are wrong lose money, and people with better information (sometimes close to inside knowledge) bet heavily, which pulls the price toward the real probability.
- Practising forecasting. Write down your own probability before looking at the price, then compare. Over many questions you learn whether you are over- or under-confident.
- Feeding an agent. Prices, history and order books are available as JSON, so an agent can watch questions you care about and summarise changes.
- Trading, if it is legal where you live and you accept that you can lose the money.
Treat a price as a signal, not a fact. Thin markets (little volume) can be moved by a few people, and a market only answers the exact question in its rules.
03 · Setup
How to get started
- Just read. Open polymarket.com and browse. No sign-up needed.
- Install the official command-line tool if you want an agent to use it:
brew tap Polymarket/polymarket-cli https://github.com/Polymarket/polymarket-cli
brew install polymarket
polymarket status
- Check whether your region is allowed:
polymarket clob geoblock. Polymarket is restricted in a number of countries; follow your local law. - Trading only: an account (or
polymarket setupin the CLI) and a funded wallet. Skip this if you only want to read.
04 · How to use it
Day-to-day use
Common read-only commands (no wallet needed):
polymarket markets search "bitcoin" --limit 5 # find markets
polymarket markets get <market-slug> # one market: question, prices, rules
polymarket clob price-history <token-id> --interval 1d # how the odds moved
polymarket clob book <token-id> # current buy and sell offers
polymarket -o json markets list --limit 20 # JSON for scripts and agents
A market has one token id per outcome; prices and history are looked up by token id. When reading a market, always check three things: the exact question and rules, the volume, and the end date.
05 · Pitfalls
Things to watch out for
- It is real money. Prices can go to zero. Only trade what you can afford to lose, and never because an AI said so.
- Legal restrictions. Access and trading are limited in many places. Check before you trade.
- Read the rules. Markets resolve on their exact wording and resolution source, which may differ from how the headline sounds.
- Thin markets mislead. A price with little volume behind it is weak evidence.
- Keys stay with you. A wallet's private key controls the money. Never paste it into a chat, a prompt or a file an agent can read.
- The CLI is early software. Its own README calls it experimental; commands may change.
06 · Resources