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Every prediction on Polymarket US is structured around three levels: series, events, and markets. Understanding how they relate is essential for finding what you want to trade.

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Series

A series is a broad grouping of related events — like a sports league or a season. Think of it as a folder that contains many games or occurrences. Examples: NFL 2025-26 Season, NBA 2025-26 Season, March Madness 2026

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Events

An event is a specific occurrence within a series — usually a single game, match, or contest. Each event has a start time, participants, and one or more markets attached to it. Examples: Chiefs vs Eagles — Feb 9, 2026, Lakers vs Celtics — Jan 15, 2026

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Markets

A market is the actual thing you trade. It’s a single yes/no question about an event. Each market settles at $1.00 if the outcome happens and $0.00 if it doesn’t. One event can have multiple markets. For example, a single NFL game might have:
Market typeQuestionExample
MoneylineWho wins?Will the Chiefs win?
SpreadWill they win by more than X points?Chiefs -3.5
TotalWill the combined score be over/under X?Total points over 47.5
PropWill a specific thing happen in the game?Mahomes over 2.5 TDs
Series: NFL 2025-26 Season
  └── Event: Chiefs vs Eagles — Feb 9, 2026
        ├── Market: Will the Chiefs win? (moneyline)
        ├── Market: Chiefs -3.5 (spread)
        └── Market: Total points over 47.5 (total)

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Market slugs

Every market has a slug — a URL-friendly identifier like aec-nfl-kc-phi-2026-02-09. This is what you use everywhere: placing orders, fetching order books, subscribing to WebSocket streams. You can find slugs by searching or browsing markets through the API.

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Live sports data

For sports events that are in progress, you get real-time metadata like the current score, period, and whether the game has ended. This is useful if you’re building applications that react to live game state.