All the terms you'll encounter on Polymarket and Kalshi, explained clearly.
YES share: pays $1 if an event happens, $0 if it doesn't. NO share: pays $1 if the event does NOT happen. Implied probability: the market price expressed as a probability (60¢ = 60% chance). Resolution: when a market concludes and payouts are distributed.
Bid: highest price a buyer will pay. Ask: lowest price a seller will accept. Bid-ask spread: the gap between bid and ask — a hidden cost of trading. Liquidity: how easily you can trade without moving the price. Slippage: the cost of trading in low-liquidity markets.
Calibration: how accurate probability estimates are over many predictions. Edge: the gap between market price and your estimated true probability. Expected value: edge × potential payout — the foundation of profitable trading. Base rate: historical frequency of similar events.
USDC: dollar-pegged stablecoin used by Polymarket. Polygon: blockchain network Polymarket runs on. KYC: identity verification required by Kalshi. CFTC: US regulator that oversees Kalshi. Oracle: system that verifies real-world outcomes for smart contracts.
What is a prediction market → Polymarket vs Kalshi →