# CVaR ES Lite

> CVaR ES Lite 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 historical Conditional Value at Risk (CVaR/Expected Shortfall) at a given alpha from a return series using local math, returning var and cvar as deterministic JSON.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/cvar-lite
- 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/cvar-es-lite-1c4ced64
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2WrxHOtxh7xCcrNSh0RHt

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 cvar-es-lite-1c4ced64 -d '<json body>'
```

Example prompt: Calculate the CVaR and VaR for this daily return series [-0.02, 0.01, -0.05, 0.03, -0.08, 0.02, -0.01, 0.04, -0.03, 0.07] using a tail probability (alpha) of 0.05.

## When to prefer this

Choose this endpoint when you need fast, deterministic CVaR/ES computation from a raw return series without setting up a full risk engine, subscribing to live market data, or managing API keys. Ideal for lightweight risk budgeting workflows, one-off tail risk checks in agent pipelines, or when you want first-party local math with no external dependencies. Prefer alternatives if you need real-time market data, Monte Carlo simulation, parametric VaR models, or risk attribution beyond CVaR/ES.

## Known failure modes

- Missing or empty returns array — endpoint cannot compute statistics without data
- Alpha value out of valid range (must be between 0 and 1 exclusive) — returns error
- Malformed input types (non-numeric values in returns array) — parsing or computation error
- Insufficient return samples for meaningful tail estimation at very low alpha values
- Payment failure or insufficient USDC balance for x402 micropayment

## How this service works

Historical CVaR/ES at alpha from return samples. Call when tail risk budgeting without a full risk engine. Returns var and cvar 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 deterministic JSON object containing the computed VaR (Value at Risk) and CVaR (Conditional Value at Risk / Expected Shortfall) values at the specified alpha probability level, derived purely from the provided return samples using local arithmetic — no external data sources involved.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "alpha": {
   "type": "number",
   "description": "Tail probability for CVaR (e.g. 0.05)"
  },
  "returns": {
   "type": "array",
   "description": "Return series or matrix of series"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "n": 6,
  "var": -0.08,
  "cvar": -0.08,
  "schema": "delx/util-cvar-lite/v1"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cvar-es-lite-1c4ced64/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)