How Prediction Markets Work

From contract mechanics to price discovery — the fundamentals of event trading.

The basic contract

A prediction market contract is a binary instrument. You buy a contract that pays out $1.00 (or €1.00) if a specific event occurs — and $0.00 if it doesn't. The price of the contract reflects the market's implied probability of the event happening.

If a contract trades at $0.65, the market implies a 65% probability. If you think the real probability is 80%, you buy — the gap between your estimate and the market price is your expected edge.

Order book vs. bookmaker

This is the fundamental difference from sports betting. A bookmaker sets the price and takes the other side of every trade — with a built-in margin (the vig). A prediction market uses an order book where buyers and sellers trade against each other. The price is set by supply and demand, not by the house.

Result: prediction market prices tend to be more efficient (closer to true probability) because they reflect collective intelligence rather than one bookmaker's risk model.

Price discovery in real time

Prices move continuously as new information arrives. When a central bank hints at rate changes, the Fed rate contract adjusts within seconds. When a key player gets injured, the match contract reprices immediately. This is price discovery — the market aggregating all available information into a single number.

Settlement and resolution

At the event outcome, contracts resolve to $1.00 (Yes) or $0.00 (No). Most platforms use automated oracles — data feeds that determine outcomes algorithmically. Some use human resolution committees for ambiguous cases.

Two modes of participation

You can engage with prediction markets at two levels:

Reputation-based forecasting

No real money. You forecast probabilities and build reputation through accuracy (Brier Score) and simulated P&L. This is how Altus Alpha works. Free, legal everywhere, pure skill measurement.

Real-money trading

Actual money on regulated platforms. Requires the same discipline as professional trading — position sizing (Kelly Criterion), expected value calculation, and risk management.

FAQ

Is this gambling?
Regulated prediction markets are classified as event contracts, not gambling. CFTC-regulated platforms like Kalshi operate as designated contract markets. Reputation-based forecasting (like Altus Alpha) involves no money at all.
What's the minimum to start?
On Altus Alpha: $0 — it's free reputation-based forecasting. On Kalshi: typically $1 per contract. On Polymarket: you need USDC cryptocurrency.
Can I sell before the event?
Yes. Unlike sports bets, prediction market contracts can be sold at any time before resolution. If the price moves in your favor, you can lock in profit without waiting for the outcome.