A prediction market is a market where people trade shares that pay $1 if an event happens and $0 if it does not, so the share price works as the crowd's estimate of the chance. On Nimb, every circle on the map is one of these markets on Polymarket, and its price is shown as a chance in %.
What is a prediction market?
The question is written in advance, with a deadline and a named source that will settle it: "Will the Fed cut rates at its December meeting?", "Who will win the 2028 US presidential election?", "Will the Israel–Iran ceasefire hold through December 31?". Each possible answer is an outcome, and each outcome has its own price. Economists also call these contracts event contracts or binary options; the idea is decades old, and the academic case for it is set out in Wolfers and Zitzewitz, "Prediction Markets", Journal of Economic Perspectives (2004).
Polymarket is the largest crypto-based prediction market. It runs on the Polygon blockchain, and trades are settled in pUSD, a dollar token backed by USDC. Nimb reads Polymarket's public data and draws it as a map. Nimb is not affiliated with Polymarket.
How does a share that pays $1 work?
Every binary market has two kinds of share: a Yes share and a No share. When the market resolves, one of them is worth $1 and the other $0. Together they are a complete set: one Yes plus one No always pays exactly $1, whatever happens.
So the two prices are complementary. Take a market where Yes trades at $0.41. No then trades at about $0.59, because $0.41 + $0.59 ≈ $1. The small gap from exactly $1 is the spread between the best buy and sell prices (see Polymarket odds explained).
| You buy | Price per share | Shares for $100 | Paid if Yes | Paid if No |
|---|---|---|---|---|
| Yes | $0.41 | ≈ 244 | ≈ $244 | $0 |
| No | $0.59 | ≈ 169 | $0 | ≈ $169 |
Figures are before fees. On Nimb the amount you type is all-in: fees are folded into the shares, so you receive slightly fewer than the table shows. You do not have to hold until the end: you can sell your shares at the current price at any time while the market is open.
The price reads as a chance. If traders will pay $0.41 for something that pays $1 when an event happens, the market as a whole puts that event at about 41%. Nimb never shows cents; it writes "41%". That number is the crowd's estimate, not a forecast by Nimb.
Who is on the other side of my trade?
Another trader. Polymarket matches orders on a peer-to-peer central limit order book (CLOB): people post the prices at which they are willing to buy and sell, and a trade happens when a buyer and a seller agree. There are no house odds. Polymarket does not set the price and does not take the other side of your position.
When you buy Yes at 41%, someone is selling you Yes at 41%, or buying No at 59%; the exchange pairs the two orders and mints a fresh $1 set if needed. Some of the people resting orders on the book are market makers who quote both sides and earn the spread. How much you can trade near the displayed price depends on the depth of the book.
How is a prediction market different from betting with a bookmaker?
| Bookmaker | Polymarket | |
|---|---|---|
| Who sets the price | The bookmaker, with a built-in margin | Traders, through the order book |
| Who takes the other side | The bookmaker | Another trader |
| Can you exit early | Sometimes, at the bookmaker's cash-out price | Yes, sell at the market price while it trades |
| Winning accounts limited | Common practice | No house to limit you; you trade against others |
| How the platform earns | The margin in the odds | Trading fees, set per market |
| What is traded | Mostly sport | Politics, geopolitics, economics, crypto, technology, sport, culture |
The practical difference for you: the price on a prediction market is information produced by people risking money, which is why it can be read like a news source (see prediction markets as a news instrument).
What kinds of events are traded?
On 2026-11-07 Polymarket listed about 2,100 active events, with $46.8M traded in the previous 24 hours and $514M over 30 days (Gamma API, 12:39 UTC). Nimb shows the 110 most active, undecided markets per timeframe, sorted into seven colours. Each category gets room in proportion to the money traded on its undecided outcomes, with at least 4 markets and at most 40% of the map.
| Category | Colour on the map | Examples (2026-11-07) |
|---|---|---|
| Geopolitics | Red | Israel–Iran ceasefire through a date; next prime minister of Sweden; Israel's prime minister after the next election |
| Politics | Blue | 2028 US presidential winner; Democratic nominee for 2028; who leaves the Trump administration before 2027 |
| Finance | Yellow | Fed decision in December; the price NVIDIA reaches in November |
| Crypto | Orange | The price Bitcoin reaches in November; Bitcoin and Ethereum up or down on the day |
| AI & Tech | Green | Release dates of new AI models; an Anthropic IPO by a date |
| Sports | Khaki | Premier League and Serie A matches; League of Legends Worlds |
| Climate & Culture | Purple | Highest-grossing film of 2026; next James Bond actor; daily high temperature in Miami |
Markets change every few hours, so these are examples, not a list. The current set is on all markets, and how each category is drawn is on categories.
Who trades and why?
- People with a view. They think the price is wrong and want exposure to the outcome: a politics follower who reads the polls differently, a sports fan who follows team news.
- Hedgers. Someone whose business or portfolio suffers if an event happens can buy Yes as insurance.
- Market makers. They post buy and sell orders on both sides, earn the spread and often end up holding both Yes and No. Nimb nets those hedged positions out when it shows holders.
- Arbitrageurs. They trade when related prices disagree, for example when the outcomes of one event add up to more than 100%.
- Large holders. A few wallets hold big positions in some markets. Nimb shows the top holders per side, because a price held up by one wallet means less than one held up by many.
Wallet addresses on Polymarket are public, so positions can be seen. Names behind them usually cannot.
What can a prediction market not do?
- It cannot tell you what will happen. A 70% chance means the event fails about 3 times in 10. Being on the losing side of a 70% market is normal, not a malfunction.
- It is only as good as its traders and its money. A market with little volume or one dominant holder can sit far from any reasonable estimate (see are prediction markets accurate?).
- It prices the question as written. If the rules are ambiguous, the price mixes the chance of the event with the chance of a disputed reading. Read the rules first (see how markets resolve).
- It is not a savings product. You can lose your whole stake. Polymarket lists the United States, the United Kingdom, France and about 35 other countries as close-only: you can close positions there but not open new ones (see eligibility).
Used with those limits in mind, a prediction market is a live, money-backed estimate that you can read before you decide anything. Market reading, in Nimb's terms, is working out what a prediction market's price, flow and holders say about an event, and how much to trust it.
Last reviewed 2026-11-07 · Data from Polymarket · Not financial advice · Nimb is not affiliated with Polymarket.