# Prediction Market Similarity Search

> Prediction Market Similarity Search is a paid API for AI agents from api.predictionmarketdata.io, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Returns semantically similar prediction markets given a source event ticker identifier.

## Facts

- Endpoint: GET https://api.predictionmarketdata.io/prediction-markets/similar
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/prediction-market-similarity-search-81998cc2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WIHwBxWSplGoEA8H6fYY8

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability prediction-market-similarity-search-81998cc2
```

Example prompt: Show me up to 10 prediction markets that are semantically similar to the event ticker INXU-2024-Q3 on predictionmarketdata.io, starting from the first result.

## When to prefer this

Use this endpoint when you need to discover related or comparable prediction markets based on a known event ticker — ideal for building recommendation feeds, exploring correlated events, or diversifying a prediction market portfolio. Prefer over full-text search when semantic similarity is more important than keyword matching.

## Known failure modes

- Invalid or unknown event_ticker returns empty results or 404
- Missing required event_ticker parameter returns 400 bad request
- limit or offset out of range may return validation error
- Payment failure (x402) if USDC balance is insufficient
- Rate limiting if too many requests in a short period

## How this service works

Find semantically similar prediction markets given an event_ticker.

## Output

A paginated list of semantically similar prediction markets for the given source event ticker, likely including market identifiers, names, exchange info, and similarity signals.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "event_ticker",
      "limit",
      "offset"
     ],
     "properties": {
      "limit": {
       "type": "string",
       "description": "Maximum number of similar events to return."
      },
      "offset": {
       "type": "string",
       "description": "Zero-based result offset."
      },
      "event_ticker": {
       "type": "string",
       "description": "Source market identifier from /prediction-markets."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "similar": [
   {
    "score": 0.91,
    "event_ticker": "spurs-vs-knicks-game-3.POLYMARK"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/prediction-market-similarity-search-81998cc2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.predictionmarketdata.io](https://www.zero.xyz/host/api.predictionmarketdata.io/llms.txt)