# market-probability

> market-probability is a paid API for AI agents from x402.fenixfoundry.com, paid per call via x402, $0.015/call, status unknown (last checked 2026-09-15).

Takes a plain-English event question and returns implied probabilities from live Polymarket and Kalshi prediction markets, including per-venue odds, a liquidity-weighted consensus forecast, and a cross-venue divergence flag.

## Facts

- Endpoint: POST https://x402.fenixfoundry.com/probability
- Price: $0.015/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/market-probability-59e4e1df
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_O7d4HQoP47mwcEhb0ficn

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 market-probability-59e4e1df -d '<json body>'
```

Example prompt: What do prediction markets currently think is the probability that the Fed cuts interest rates before September 2026? Pull odds from both Polymarket and Kalshi and give me the liquidity-weighted consensus, looking at up to 6 matched markets.

## When to prefer this

Use this endpoint when you need real-time, crowd-sourced probability estimates for future events expressed in plain English. It is ideal when you want a consensus view aggregated across both Polymarket and Kalshi rather than a single venue, and when you need the liquidity-weighted probability rather than a simple average. Prefer this over manual market searches when the question is ambiguous or when cross-venue divergence is relevant to a decision. If the event has already resolved, use the market-resolution sibling endpoint instead.

## Known failure modes

- No matching prediction market found for the query — returns empty or low-confidence result
- Query is too vague or ambiguous to match a specific market — returns multiple loosely related markets
- Event has already resolved and market is closed — market-resolution endpoint should be used instead
- Polymarket or Kalshi API is temporarily unavailable — partial results from only one venue returned
- Query exceeds 500-character limit — validation error
- maxMarkets out of allowed range (1–10) — validation error

## How this service works

What does the market think? Ask any event question in plain English and get the implied probability from live Polymarket and Kalshi prediction markets: per-venue odds, a liquidity-weighted consensus forecast, and a cross-venue divergence flag.

## Output

A structured response containing: matched prediction market titles and venues (Polymarket and/or Kalshi), per-venue implied probabilities, a liquidity-weighted consensus probability across all matched markets, and a divergence flag indicating whether the venues disagree significantly on the outcome. Up to maxMarkets (default 6) matched markets are aggregated and returned ranked by match quality.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "q": {
   "type": "string",
   "maxLength": 500,
   "minLength": 3,
   "description": "Natural-language description of the event you want odds for, e.g. \"Will the Fed cut rates before September 2026?\". Matched against Polymarket and Kalshi market questions."
  },
  "maxMarkets": {
   "type": "integer",
   "default": 6,
   "maximum": 10,
   "minimum": 1,
   "description": "Maximum number of matched markets to aggregate and return (top-K by match quality). Defaults to 6."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/market-probability-59e4e1df/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.fenixfoundry.com](https://www.zero.xyz/host/x402.fenixfoundry.com/llms.txt)