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Hierarchy

Bayse uses a three-level hierarchy: Event → Market → Outcome
  • An event is the top-level container. It represents a real-world question or topic — for example, “NBA Finals 2025” or “Will it rain in Lagos tomorrow?”.
  • A market is a tradeable question within an event. Each market has exactly two outcomes (e.g. YES/NO, or two named options). Prices for the two outcomes always sum to approximately 1.00.
  • An outcome is one side of a market that you can buy or sell shares in. Each outcome has a unique UUID (outcomeId) that you use when placing orders or getting quotes.

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Events

Events group one or more related markets together. Every event has a type that determines how its markets relate to each other. Key fields:
  • title — the headline question or topic.
  • type — single, combined, or grouped (see Event types).
  • category — sports, politics, crypto, entertainment, etc.
  • status — open, closed, resolved, cancelled, paused, or draft.
  • engine — AMM or CLOB (see Market engines).
  • closingDate — when trading closes.
  • resolutionDate — when the outcome is determined.

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Markets and outcomes

Each market is a binary question with two outcomes. You trade by buying or selling shares in one of the outcomes. Key fields:
  • title — the specific question (e.g. “Will Lakers win?”).
  • outcome1Id / outcome2Id — UUIDs that uniquely identify each outcome.
  • outcome1Label / outcome2Label — labels for each side (e.g. “YES” / “NO”).
  • outcome1Price / outcome2Price — current probability prices (0.00–1.00).
  • rules — resolution criteria for this market.
  • status — same set as events.
The outcomeId is the canonical way to reference an outcome. When you fetch a market, note the outcome1Id and outcome2Id — you’ll use one of these when placing orders or requesting quotes.

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Event types

One event, one market, two outcomes. The event title and market title are typically the same.
{
  "title": "Will it rain in Lagos tomorrow?",
  "type": "single",
  "markets": [
    {
      "title": "Will it rain in Lagos tomorrow?",
      "outcome1Id": "c3d4e5f6-a7b8-9012-cdef-123456789012",
      "outcome1Label": "YES",
      "outcome1Price": 0.65,
      "outcome2Id": "d4e5f6a7-b8c9-0123-defa-234567890123",
      "outcome2Label": "NO",
      "outcome2Price": 0.35
    }
  ]
}
Multiple mutually exclusive markets under one event. Only one market can resolve YES — when one wins, the others automatically resolve NO.
{
  "title": "NBA Finals 2025 Winner",
  "type": "combined",
  "markets": [
    {
      "title": "Will Lakers win?",
      "outcome1Id": "...",
      "outcome1Label": "YES",
      "outcome1Price": 0.35,
      "outcome2Id": "...",
      "outcome2Label": "NO",
      "outcome2Price": 0.65
    },
    {
      "title": "Will Celtics win?",
      "outcome1Id": "...",
      "outcome1Label": "YES",
      "outcome1Price": 0.40,
      "outcome2Id": "...",
      "outcome2Label": "NO",
      "outcome2Price": 0.60
    },
    {
      "title": "Will Nuggets win?",
      "outcome1Id": "...",
      "outcome1Label": "YES",
      "outcome1Price": 0.25,
      "outcome2Id": "...",
      "outcome2Label": "NO",
      "outcome2Price": 0.75
    }
  ]
}
Multiple independent markets under one event. Each market is resolved on its own — multiple markets can resolve YES.
{
  "title": "Player stats: Lakers vs Celtics",
  "type": "grouped",
  "markets": [
    {
      "title": "Will LeBron score 30+ points?",
      "outcome1Id": "...",
      "outcome1Label": "YES",
      "outcome1Price": 0.45,
      "outcome2Id": "...",
      "outcome2Label": "NO",
      "outcome2Price": 0.55
    },
    {
      "title": "Will Tatum score 25+ points?",
      "outcome1Id": "...",
      "outcome1Label": "YES",
      "outcome1Price": 0.60,
      "outcome2Id": "...",
      "outcome2Label": "NO",
      "outcome2Price": 0.40
    }
  ]
}

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Finding markets

Use the keyword query parameter on the List events endpoint to search for events by title: 
GET /v1/pm/events?keyword=lagos&status=open
You can also filter by category, status, trending, and more. See the List events reference for all available filters.