予測市場は
どのように機能するか？
A prediction market is an online platform where people buy and sell event contracts (financial instruments that pay a fixed amount if a specified future event occurs and nothing if it does not). The price of a contract reflects the market's collective estimate of how likely the event is to happen.
質問から支払いまで
1. Pick a market
Every market resolves on a single well-defined question: "Will the Fed cut rates at its next meeting?", "Will Team A win the championship?", "Will CPI exceed 3.0% year-over-year?" The question must be binary (yes/no) or have a clearly enumerable set of outcomes, and it must have an objective resolution date.
2. Buy YES or NO shares
Each contract is split into YES and NO shares. A YES share pays $1 if the event happens; a NO share pays $1 if it does not. Their prices always sum to roughly $1, so buying one of each locks in exactly $1 at resolution; the individual prices can be read directly as implied probabilities.
3. Trade or hold
You can sell your position any time the price moves, locking in profit or cutting a loss, or you can hold to resolution and collect the full $1 on the winning side. Holding to resolution ties up capital but avoids slippage.
4. Resolution and payout
When the event is decided, the operator (or a decentralized oracle like UMA on Polymarket) marks the market resolved. Winning shares pay out $1 each; losing shares pay zero. On regulated venues like Kalshi, proceeds settle in USD to your account. On on-chain venues like Polymarket, they settle in USDC to your wallet.
仕組みをさらに深く理解する
以下の各ガイドは、メカニズムの一部に焦点を当てた詳細解説です。完全な理解を構築するには順番に読むか、理解したい概念に直接ジャンプしてください。
What is implied probability in prediction markets?
Why a YES share trading at $0.62 means a ~62% market-implied probability, and when that reading breaks down.
パート 2Order books vs AMMs in prediction markets
Kalshi and Polymarket run orderbooks; older on-chain venues use automated market makers. How each one prices risk differently.
パート 3What is LMSR (Logarithmic Market Scoring Rule)?
The market-maker formula Robin Hanson designed for prediction markets, why it bounds loss, and who still uses it.
パート 4How liquidity works in prediction markets
Why liquidity is the single biggest predictor of accuracy, how thin markets are manipulated, and what "depth" really means.
パート 5Bid, ask, and spread explained
The three numbers every event-contract trader should read before placing an order, with worked examples from Kalshi and Polymarket.
パート 6How prediction market resolution works
What happens when a market settles: centralized operators, UMA oracles, community voting, and what to do when resolution is disputed.
パート 7Market manipulation in prediction markets
How traders move thin markets to generate headlines or profit, how to detect manipulation, and why deep liquidity is the only real defense.
パート 8Kelly criterion for event contract sizing
How to size positions in binary markets using the Kelly formula, why fractional Kelly is safer in practice, and how fees change the math.
パート 9Arbitrage across prediction markets
How to find and trade price discrepancies between Kalshi, Polymarket, and other venues, the mechanics of locking in risk-free profit, and practical limits.
パート 10How prediction market winnings are taxed
US tax treatment under current IRS guidance, what 1099-MISC means for Kalshi traders, and how other jurisdictions generally handle prediction market profits.
パート 11Sports contracts vs political contracts
How CFTC-regulated sports event contracts differ from political ones in regulation, resolution mechanics, and what that means for traders outside the US.
パート 12How to read a prediction market orderbook
Level 2 depth, bid and ask walls, how large orders signal conviction or manipulation, and what the top-of-book tells you before you place a trade.
パート 13What is a Designated Contract Market (DCM)?
The CFTC licence that Kalshi, ForecastEx, and Robinhood hold, what it means for consumer protection, and why it matters for US prediction market access.