Prediction Markets Explained: How Polymarket and Crypto Betting Actually Work
How prediction markets like Polymarket work, the mechanics behind the odds, and why UK residents currently face legal access restrictions.
A Polymarket trader turned $8,000 into more than $1 million betting on the 2024 US election outcome. Stories like that pull people in fast. But prediction markets aren’t a new crypto gimmick — they’re an old idea, wrapped in blockchain settlement, and UK users need to understand how the mechanics actually work before putting money anywhere near one.
What Are Prediction Markets?
A prediction market lets people trade on the outcome of a future event. Will a particular bill pass? Will a central bank cut rates? Will a specific film hit a box office number? Each outcome becomes a tradeable share.
Share prices move between £0 and £1 (or $0 and $1 on dollar-denominated platforms), and the price reflects the market’s collective probability estimate. A share trading at 70p implies traders think there’s roughly a 70% chance the event happens.
This isn’t new. Economists have studied prediction markets since the Iowa Electronic Markets launched in 1988. What’s changed is the plumbing — crypto rails now settle these bets instantly, globally, without a bookmaker in the middle.
How Polymarket and Similar Platforms Work
Polymarket runs on Polygon, an Ethereum scaling network, and settles trades in USDC. Users deposit stablecoins, buy shares in an outcome, and cash out when the market resolves — or sell early if the price moves in their favour.
Kalshi takes a different path. It’s a US-regulated exchange, overseen by the Commodity Futures Trading Commission, and it uses real dollars rather than crypto rails. That regulatory status matters a lot for what happens next.
Both platforms rely on liquidity providers and automated market makers to keep spreads tight. Popular markets — a US election, a major sports final — can see tens of millions in daily volume. Obscure ones barely trade at all.
The Mechanics: Shares, Odds and Settlement
Buy a “Yes” share for 60 cents. If the event happens, that share resolves to $1 — a 67% return. If it doesn’t happen, the share resolves to zero and you lose the full 60 cents.
Resolution depends on an oracle — a data source the platform trusts to confirm the real-world outcome. Polymarket uses UMA’s optimistic oracle, where anyone can dispute a proposed resolution within a set window.
That dispute window is where things get messy. Ambiguous questions, contested news events and slow-moving disputes have all caused resolution delays running into days or weeks on high-profile Polymarket markets.
Real Money vs Play Money Prediction Markets
Not every prediction market involves real stakes. Metaculus and Good Judgment Open use points or reputation, not money, aimed at forecasting accuracy rather than profit.
Real-money markets attract sharper, faster-moving prices because traders have skin in the game. Play-money markets attract more participants overall but tend to price outcomes less precisely.
For anyone researching a topic rather than betting on it, the free forecasting sites are genuinely more useful. The accuracy research behind them, going back to Philip Tetlock’s “superforecasters” work, holds up well.
Legal Status in the UK
Here’s where UK readers hit a wall. Polymarket blocks UK IP addresses. It has done since the platform launched, because unlicensed betting exchanges fall foul of the UK Gambling Commission’s licensing regime.
Using a VPN to route around that block is against Polymarket’s own terms of service, and it also strips away whatever limited consumer protection UK gambling law would otherwise offer.
Kalshi has similar restrictions outside the US. UK residents genuinely interested in this space are largely limited to traditional licensed betting exchanges like Smarkets or Betfair, which the FCA and Gambling Commission both already regulate.
Risks: Manipulation, Insider Trading and Liquidity
Small prediction markets are easy to move. A single large trade on a thin market can swing the implied probability by 20 percentage points or more, distorting the very signal people are trying to read.
Insider trading concerns are real too. Someone with early access to a corporate announcement or election result could trade ahead of the news, and there’s limited enforcement capacity across a decentralised platform base.
Then there’s plain liquidity risk. Wide bid-ask spreads on unpopular markets mean the price you see isn’t always the price you’ll actually get when you try to exit.
Prediction Markets vs Traditional Betting
Betfair has run a peer-to-peer betting exchange since 2000, regulated, taxed, and familiar to UK users. Prediction markets pitch themselves as smarter — trading probability, not gambling on an outcome.
The line between the two is thinner than either side admits. Both involve staking money on an uncertain future event, and both can produce life-changing wins or painful losses depending on timing and luck.
What genuinely differs is transparency. On-chain settlement means every trade on Polymarket is publicly verifiable. Traditional bookmakers don’t expose their books the same way.
Notable Prediction Market Wins and Failures
The 2024 US presidential election became Polymarket’s defining moment. Volume topped $3.6 billion across the election cycle, and the platform’s odds moved faster than most traditional polling, drawing coverage from mainstream news outlets that had previously ignored crypto entirely.
Not every market resolves cleanly. A 2024 Polymarket question about a geopolitical event sparked a genuine dispute over the wording of the original question, leaving traders locked in limbo for days while the UMA oracle process played out publicly.
Sports markets have caused headaches too. Ambiguous resolution criteria — what exactly counts as a “win,” when overtime or a technicality is involved — have repeatedly triggered community disputes that testing before launch should have caught.
The lesson for anyone studying this space: the technology works, but the human judgement behind writing and resolving market questions remains the weakest link in the whole system.
How Institutions Are Using Prediction Markets
Hedge funds now treat prediction market odds as a genuine data source, feeding them into broader trading models alongside polling data, betting exchange prices and social sentiment analysis.
Some academic researchers argue prediction markets outperform expert forecasts for short-term political and economic events, because traders have direct financial skin in the game rather than professional reputation alone.
A handful of corporates have piloted internal prediction markets too — letting employees bet on whether a product ships on time, or whether a project hits its target. Google famously ran internal markets like this for years.
Whether that data proves more reliable than a good analyst team long-term is still genuinely contested. Early results look promising. The sample size, across only a few major election cycles, remains small.
Prediction Markets and Crypto: The Overlap
Polymarket only exists in its current form because of crypto rails. Instant, low-fee stablecoin settlement made it viable to run thousands of niche markets simultaneously, something a traditional bookmaker’s back office would struggle to handle profitably.
That dependency cuts both ways though. Polymarket users are exposed to USDC’s peg stability, Polygon network fees and smart contract risk, on top of whatever risk they’re actually trying to trade on the underlying event.
Some newer platforms are experimenting with fully on-chain resolution, removing human oracles entirely in favour of automated data feeds. Early versions remain limited to markets with clean, verifiable outcomes — sports scores, price levels — rather than contested political events.
The broader crypto industry is watching closely. If prediction markets prove durable and genuinely useful, they could become one of the strongest real-world use cases blockchain technology has produced outside pure currency speculation.
Common Questions About Prediction Markets
Can UK residents use Polymarket legally? No, not directly. Polymarket blocks UK IP addresses because it lacks a UK gambling licence, and bypassing that block breaches the platform’s own terms of service.
Are prediction markets gambling? Functionally, yes, though platforms usually describe them as financial or forecasting tools to sidestep gambling regulation. The economic behaviour — staking money on an uncertain outcome — is the same either way.
Is there a legal UK alternative? Betfair and Smarkets offer similar peer-to-peer exchange betting, fully licensed by the Gambling Commission, with UK consumer protections Polymarket simply doesn’t provide.
What This Means for You
Prediction markets are a fascinating experiment in crowd-sourced forecasting, but for UK users the practical reality is blocked access, unclear tax treatment, and no domestic regulatory protection if something goes wrong.
If you want exposure to this kind of trading, stick to Gambling Commission-licensed exchanges. If you want the forecasting insight without the financial risk, free platforms like Metaculus do the same job legally, from the UK, today.
Keep an eye on this space regardless. If a UK-licensed prediction market platform eventually launches with proper Gambling Commission oversight, it could combine the transparency crypto rails offer with the consumer protections domestic regulation actually provides.
UK investors keep asking whether this counts as the next big crypto trend or just a passing novelty. Right now it’s neither settled. Watch the regulatory door before you watch the odds, because right now the door stays shut for anyone browsing from Britain.
For now, the smart move is patience. Follow the sector, understand the mechanics, and wait for a properly licensed route before committing real money to any prediction market from a UK address.
This article is for educational purposes only and does not constitute financial advice. Cryptocurrency investments involve significant risk. Always do your own research.
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