# Carbon Cashmere Beta-to-BTC Regression API

> Carbon Cashmere Beta-to-BTC Regression API is a paid API for AI agents from api.carbon-cashmere.de, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-14).

Calculates a cryptocurrency's beta coefficient versus Bitcoin using OLS regression on 4-hour returns with rolling 30-day stability analysis, regime classification, and alpha/R-squared metrics.

## Facts

- Endpoint: GET https://api.carbon-cashmere.de/v1/beta-to-btc/:coin
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-carbon-cashmere-de-54f8fe7a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_FhnenaDClTI7tAs8lVLmv

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 api-carbon-cashmere-de-54f8fe7a
```

Example prompt: What's SOL's beta to Bitcoin right now — is it an amplifier or decoupled, and how stable has the beta been over the last 30 days?

## When to prefer this

Use this endpoint when you need a quantitative, regression-based measure of how a specific altcoin moves relative to Bitcoin — particularly when regime classification (amplifier vs decoupled) and rolling stability analysis matter. Prefer this over simple correlation endpoints when you need alpha, R-squared, and 30-day rolling coefficient-of-variation for research or portfolio risk profiling.

## Known failure modes

- Unsupported coin ticker returns a 400/422 validation error — only 34 enumerated coins are supported
- Network or upstream data outage may return a 500 or timeout
- Payment failure (x402) if USDC balance is insufficient for the $0.01 per-call fee
- BTC queried against itself may return trivial beta=1 results

## How this service works

Beta coefficient of coin vs BTC via OLS regression on 4h returns + rolling 30d stability analysis. Returns full-period beta, alpha (daily pct), r-squared, regime classification (high_amplifier/amplifier/coupled/partial_coupled/decoupled/inverted), and rolling 30d stats (mean/std/min/max). Stability rating (stable/moderate/unstable) based on coefficient-of-variation. Informational research data — not investment advice.

## Output

Returns full-period beta coefficient, daily alpha percentage, R-squared fit, a regime label (one of: high_amplifier/amplifier/coupled/partial_coupled/decoupled/inverted), and rolling 30-day statistics (mean, std, min, max beta) plus a stability rating (stable/moderate/unstable) based on coefficient of variation.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/api-carbon-cashmere-de-54f8fe7a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.carbon-cashmere.de](https://www.zero.xyz/host/api.carbon-cashmere.de/llms.txt)