Article
What moved in prediction markets today? A free tool that shows you in one glance
If you follow Polymarket — or any prediction market — you've felt the problem: something big happened, the crowd shifted, but by the time you checked individual markets you had no sense of what moved or how much. You see one market at a time through Polymarket's search or category pages, and the big picture of what the crowd is re-pricing right now stays invisible.
That's the gap the Market Movers page fills. It polls Polymarket's open Gamma API, compares each market's current implied probability against its recent snapshot, and ranks them by absolute shift — the biggest movers first. Up, down, by how much, and what the volume looks like.
The problem with "checking Polymarket"
Polymarket lists about 200 open markets at any time. If you want to know what changed since yesterday, your options are: scroll through all of them looking for differences, or already know what you're looking for. Neither works if your question is just "what's happening?"
Prediction markets are useful precisely because they react to real events faster than news articles get written — but that speed advantage is wasted if you can't see what moved without manually diffing the whole list. Polymarket's own API returns the full market list with outcome prices, but it doesn't do the comparison for you.
How Market Movers works
The page fetches Polymarket's live market data, compares each market's current "Yes" probability against a stored snapshot from the previous fetch, and computes the absolute probability change (|Δ|). Markets with a shift of 0.05 percentage points or more are ranked by the size of that shift.
Each mover card shows:
- The current implied probability and what it was before
- The dollar volume traded in that market (a proxy for liquidity and conviction)
- An up/down arrow — green ▲ for probability increasing, red ▼ for decreasing
- A visual probability bar showing where the market was vs where it is now
Summary stats at the top tell you how many markets moved, how many went up vs down, and the average absolute shift across all movers.
You can filter by keyword (e.g. "Vance" to see only markets involving JD Vance) or by direction (up only / down only). The refresh button fetches fresh data from Polymarket's API and recomputes the deltas.
A concrete example
On election night 2024, Polymarket saw some of its heaviest trading volume — over $300 million in a single market. A tool like Market Movers would have shown, in one page load, which state-level markets were shifting hardest and in which direction, rather than requiring someone to watch a dozen markets individually.
The page loads with a recent seed snapshot so you see data immediately, even if the live API is slow or unreachable. Then it refreshes from the live API in the background.
Who it's for
- Prediction market enthusiasts who check Polymarket regularly and want a quick daily overview.
- Anyone following election odds, crypto governance markets, or event-driven binary markets — the 2028 US presidential election alone has over a dozen active markets on Polymarket.
- Journalists and analysts who want a quick read on what the crowd is pricing in or out, without spending 20 minutes scrolling.
How it fits with the Polymarket Scanner
The Polymarket Scanner (the parent tool) lets you browse all live markets sorted by volume, liquidity, or closing date, with keyword filtering and implied probabilities at a glance. Market Movers is the complement: the overview you check first to see what changed today, before diving into individual markets.
Together they form a free, no-signup, no-wallet dashboard for Polymarket data — everything runs in your browser, reading Polymarket's public API directly. No accounts, no tracking beyond a privacy-respecting visit counter.
Try it
→ Market Movers — Polymarket Probability Changes
Free, no signup, works in your browser.