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Return Tail Statistics Calculator
x402
Return Tail Statistics Calculator is a paid API for AI agents from heb-utils-x402.hebutils-api.workers.dev, paid per call via x402, $0.05/call, status unknown (last checked 2026-10-11).
Computes lower-tail quantile and conditional mean (CVaR-style) from a user-supplied series of periodic returns
Price / call$0.05
Success—
StatusUnknown
How this service works
Empirical lower-tail statistics of periodic returns you supply (decimals, 20-250 values): lower quantile and mean of observations at or below it. Numbers only, documented convention. Not advice, not a risk limit.
Output
Returns the lower-tail quantile at the specified confidence level and the mean of all observations at or below that quantile, computed empirically from the supplied return series. Output is numeric — no advice or risk limits included.
Example use cases
Portfolio downside risk assessment
“I have 120 monthly returns from my equity portfolio as decimals. Can you compute the lower-tail quantile and mean of the worst 5% of observations using a 0.95 confidence level?”
Strategy backtesting tail analysis
“Here are 80 weekly returns from my trading strategy: 0.01, -0.04, 0.02, -0.07 … Can you calculate the lower quantile and average return below the 0.90 confidence level so I can see how bad the tail looks?”
Risk comparison across asset series
“I want to compare the tail risk on two assets — here are 50 daily returns for asset A. Give me the lower quantile and conditional mean below the 0.975 confidence level.”
Technical details
Endpoint
GEThttps://heb-utils-x402.hebutils-api.workers.dev/return-tail-stats?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need empirical lower-tail statistics (quantile + conditional tail mean) computed directly from a user-supplied return series of 20–250 observations, without needing a full risk platform or advisory service. It is ideal for lightweight, on-demand quantitative risk summaries in agent workflows where pay-per-call USDC micropayments are acceptable and no server-side data storage is needed.
Side effects
- Fewer than 20 or more than 250 values supplied — request rejected
- Non-numeric or malformed comma-separated string causes parse error
- Confidence level outside 0.5–0.999 range causes validation failure
- Payment not made (x402 payment required before response is returned)
- Too few observations below the quantile threshold to compute a stable mean
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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