# PairBook

> Correlation, covariance, beta and holdings overlap for 4755 US stocks and ETFs.

- **Website:** https://pairbook.io
- **Pricing:** unknown
- **Categories:** Data & Analytics, Design
- **Tags:** data-analytics, design
- **Platforms:** Windows
- **Last verified:** 2026-09-10
- **Canonical page:** https://linkrena.com/tools/pairbook

## About

52,358 pair analyses across 4755 US assets: correlation, covariance, beta, volatility, and true holdings overlap. Two funds can move together and own the same stocks. PairBook measures both, and serves all of it as a free JSON API.

Holdings overlap between major index and sector ETFs: how much of the same portfolio you would own twice.

Every figure on the site, as static JSON: per pair, per asset, plus a full index. No key, no signup, CORS open. Attribution is the only ask.

Every pair has an SVG badge for READMEs, notebooks and dashboards. It updates with the data.

Pearson on weekly returns, windows of 1/3/5 years, beta vs SPY, overlap as minimum common weights. Formulas included, every number reproducible.

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