Prediction Markets Explained: Buying a Dollar at a Discount

There's a contract on Polymarket right now asking whether Spain will win the 2026 FIFA World Cup. It's trading at 15 cents.

That means: pay 15 cents, collect $1 if Spain wins.

If you think Spain's chances are better than 15% (maybe you've been watching La Liga, maybe you feel it), then in prediction market terms, you're looking at a dollar on sale. You're not "gambling on soccer." You're buying a dollar at a discount, with your edge being that you think the crowd has Spain priced too low.

That's the whole idea. Everything else in prediction markets is a variation on this one mechanic.

What a prediction market contract actually is

A prediction market contract is a financial instrument tied to the outcome of a specific future event. Every contract pays exactly $1 per share if the event occurs, and $0 if it does not. The price sits somewhere between $0 and $1 and represents what the market collectively believes the probability of that outcome is.

Price = implied probability. Payout = $1 if right, $0 if wrong.

Here's what that looks like with real numbers:

Contract: "Will the US national debt exceed $40 trillion by end of 2026?" Current price: 62¢ You buy: 100 contracts for $62 If yes: You collect $100. Profit: $38. If no: You lose $62.

The contract doesn't care about your feelings on fiscal policy. It pays $1 or it pays $0. The question is whether you think 62%, the crowd's current estimate, is too low, too high, or about right.

Why 62¢ means 62%

The price isn't arbitrary. It's the result of thousands of traders independently deciding whether to buy or sell. Those decisions push the price toward the crowd's consensus estimate of the true probability.

Here's the logic: if a contract is at 62¢ but most informed traders believe the true probability is 80%, they'll all buy. Demand rises, price rises, until it reaches roughly 80¢, the point where buyers and sellers disagree equally. If traders believe the true probability is only 40%, they'll sell, pushing the price down until it reflects that.

Here's why it works: no single person knows everything about the US fiscal trajectory. But thousands of people, each putting money behind their own read of the situation, collectively encode more information than any one of them holds. That aggregate judgment gets compressed into a single number. That number is 62¢.

What moves prices? New information. A debt ceiling vote, an unexpected GDP print, a policy announcement. Any of these can shift the crowd's assessment instantly, and the price follows.

When you're buying a dollar at a discount

The edge is the gap between the market price and what you think the true probability is.

If a contract is at 40¢ and you believe the real probability is 60%, you're buying a dollar for 40 cents when, in your view, it's worth 60 cents. That's a 20-cent theoretical edge per contract. Multiply by 100 contracts and you've got a $20 expected profit on a $40 investment, if you're right about your edge. Whether your edge is real is a separate question.

If a contract is at 80¢ and you believe the real probability is 60%, you're doing the opposite: overpaying. You're buying a dollar for 80 cents when you think it's worth 60. That's a losing bet in expectation, even if the event ends up happening.

This is why prediction markets reward people with genuine information advantages. The market price is an average of everyone's beliefs. If you know something the average doesn't, local voter data, insider industry knowledge, a model that correctly prices an event at 70% when the market says 55%, the price is wrong in your favor. You're looking at a discount dollar.

If you don't have an edge, the price is probably close to right. You're buying at fair value, which is a break-even proposition before fees.

You don't have to wait for the answer

Prediction markets trade more like stocks than bets. You're not locked in. Your position has a live price, and you can sell at any point before the event resolves.

If you bought a Spain World Cup contract at 15¢ and three months later (after Spain wins every group stage match convincingly) the price has moved to 35¢, you can sell at 35¢ and pocket 20¢ profit per contract without waiting for the final in July.

In the lead-up to Super Bowl LX, Kalshi and Polymarket had contracts on the Seattle Seahawks trading at 68¢. Traders who bought before the game could have sold at 90¢ in the fourth quarter when a Seattle win looked near-certain, collecting profit before the final whistle, without waiting for the $1 payout.

You can be right about the direction without being right about the final outcome, and still profit from the move.

What can go wrong

The analogy works both ways.

You thought Spain was underpriced at 15¢. You bought 200 contracts for $30. Spain exits in the quarterfinals. Your contracts pay $0. You lose $30.

The market was right. Your edge was an illusion.

A few things make this worse than it sounds:

Thin markets. On low-volume contracts (niche events, early-stage markets) the price may not reflect genuine collective wisdom. It might reflect three traders and a lot of noise. In these markets, "the crowd says 30%" can mean almost nothing.

Overconfidence. The most common mistake. You feel certain, the price feels wrong, you size up. Prediction markets have a way of resolving on technicalities that informed-feeling traders don't anticipate. A contract asking "Will inflation fall below 3% by June 30?" can resolve No because the relevant data release came on July 2, not June 30. The underlying prediction was right. The contract still paid zero.

The market being smarter than you. If the aggregate of thousands of traders (many of whom have more information, better models, or more experience than you) says 62%, the crowd of thousands is probably closer to right than you are.

Most people who trade prediction markets lose money. Not because the markets are rigged, but because being more right than a crowd of thousands, consistently, is genuinely hard. The discount is real. The edge is the hard part.

One more risk worth knowing: the legal status of prediction markets in the US is actively contested. Some states have moved to ban or criminalize certain platforms. Before you fund an account, it's worth understanding where things stand.

Prediction markets run on one idea: let people put money behind their beliefs, and the prices that emerge will encode more information than any poll, pundit, or expert panel. The dollar-at-a-discount framing is that same idea in plain terms. You're not betting blind. You're comparing your estimate to the crowd's, and deciding whether the gap is wide enough to be worth the risk. That's a real question worth asking. Most people never get to ask it.

For a broader introduction to what prediction markets are and where they came from, see What Are Prediction Markets and How Do They Actually Work? To understand the platforms where these contracts trade, see our in depth review of Polymarket and our Kalshi review