# Binary Outcome EV (No Side) Calculator

> Binary Outcome EV (No Side) Calculator is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Computes the expected value of a 'No' position in a binary prediction market given stake, true probability, and current market price.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/binary-ev-no
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/binary-outcome-ev-no-side-calculator-1ce52f51
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZmcLbv5QxGFy8BA_AWAGJ

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 binary-outcome-ev-no-side-calculator-1ce52f51 -d '<json body>'
```

Example prompt: What's the expected value of a No position if I stake 100 units, I think the true probability is 35%, and the current No price is 0.52?

## When to prefer this

Use this endpoint when you need a fast, cheap ($0.001 USDC) server-side computation of the expected value for the No side of a binary prediction market position. Prefer it over local calculation when you want a canonical, versioned result with a schema identifier for logging or auditing, or when the computation needs to be part of an x402-powered agent workflow.

## Known failure modes

- Missing required fields (stake, true_prob, market_price) return a 400 validation error
- Probability values outside [0,1] range may return an error or nonsensical EV
- market_price of 0 or 1 causes division issues or degenerate results
- Non-integer stake may be rejected or silently coerced
- Payment failure or insufficient USDC balance returns a 402 error

## How this service works

Expected value of buying binary NO at (1−yes_price) under true_prob. Call when checking the NO side when YES is mispriced the other way. Returns EV per $1 notional on NO as deterministic JSON for $0.001 USDC via x402 on Base. First-party local math only—no RPC, live market feed, API keys, storage, or mediagen. Advisory only; the caller owns capital, risk, and production controls.

## Output

Returns a JSON object containing the computed expected value (ev, which can be negative), the stake echoed back, the number of No shares purchased, the effective no_price, and a schema identifier string (delx/util-binary-ev-no/v1).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "stake": {
   "type": "integer",
   "description": "Input field: stake."
  },
  "true_prob": {
   "type": "number",
   "description": "Input field: true prob."
  },
  "market_price": {
   "type": "number",
   "description": "Input field: market price."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ev": -13.46153846153848,
  "stake": 100,
  "schema": "delx/util-binary-ev-no/v1",
  "shares": 192.3076923076923,
  "no_price": 0.52
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/binary-outcome-ev-no-side-calculator-1ce52f51/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)