What Is a Prediction Market? Polymarket Odds vs. the Stock Market

A stock price tells you what an asset is worth. A prediction market tells you what the crowd thinks is going to happen. Read together, they answer a question neither can answer alone: not just what the market is doing, but why.

This guide explains what prediction markets are, how to interpret their odds, and how we overlay Polymarket data on price charts across Marketdeck.

What a prediction market actually is

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 Bitcoin close the year above $100k?", "Will company X beat earnings?". Each contract settles at $1 if the event happens and $0 if it doesn't.

Because of that structure, the current trading price maps directly onto a probability. A contract trading at $0.63 means the market is pricing the event at roughly a 63% chance. When new information arrives, traders buy or sell, and that price — that implied probability — moves in real time.

Polymarket is the largest such venue by volume. We read its public odds and surface them next to the assets they affect.

Why the odds are useful

Prediction-market odds have three properties that make them a strong complement to price data:

• They're forward-looking. A stock price reflects today's value; prediction odds reflect the market's expectation of a specific future outcome.
• They aggregate money, not opinions. Participants are backing views with capital, which tends to discipline wishful thinking more than a poll or social feed.
• They're event-specific. Instead of a vague "risk-on" mood, you get a number attached to a concrete catalyst — a rate decision, an election, an earnings beat.

That said, they are not crystal balls. Thin markets can be noisy, odds can be swayed by a few large traders, and a 63% event still fails 37% of the time. Treat them as one input, not a verdict.

Prediction odds vs. stock prices: a worked example

Suppose a large-cap stock is drifting lower into an earnings date while the Polymarket contract "Will company X beat Q3 estimates?" sits at 40%. The price weakness and the sub-50% odds are telling a consistent story: the market is leaning toward a miss.

Now flip it. If the same stock is rising while the beat-odds sit at 40%, you have a divergence — price strength running ahead of a skeptical event market. Divergences like that are exactly what's worth investigating on a ticker page: did the move happen before or after the odds shifted, and which one led?

For a deeper comparison of the two instruments, see our lesson on prediction markets vs. stocks.

How we use prediction markets on Marketdeck

Across the site, Polymarket data shows up in three places:

1. On ticker pages — relevant markets are linked to the symbol, so you can see the event odds that bear on a company or asset alongside its price and news.
2. On the prediction markets page — the broader macro, crypto, and event landscape, sorted by volume.
3. On the Narrative Chart — event markers place odds shifts on the same timeline as price, news, and social activity.

When the underlying odds are estimated rather than pulled from live history, we label them as such — we never present a synthetic number as a live one.

How to read the odds without overfitting

A few practical habits:

• Watch the change, not just the level. A contract moving from 45% to 60% in a day is often more informative than one sitting flat at 60%.
• Check the volume. A 70% reading on a deep, liquid market means more than the same number on a market with almost no trading.
• Line it up with price and news. The signal is strongest when sentiment, price action, and event odds agree — and most interesting when they don't.

The bottom line

Prediction markets convert scattered expectations about the future into a single, tradeable probability. Overlaid on stock and crypto prices, they turn "the market is nervous" into "the market is pricing a 40% chance of a miss." That's the layer we build the narrative timeline around.

Sources & methodology

Prediction-market odds referenced here come from Polymarket, read via its public contracts. How we ingest, cache, and label that data — including when a sparkline is an estimate rather than live history — is documented on our data methodology page. See About for our editorial standards.

Marketdeck is for informational purposes only and is not financial advice. Data may be delayed, and prediction-market odds are estimates of probability, not guarantees. See our full disclaimer.