Show HN: PairBook – correlation and holdings overlap for +4,700 US stocks/ETFs

PairBook launched a web-based tool for analyzing correlation and holdings overlap across more than 4,700 US stocks and ETFs, according to a Show HN post by the project's author, vincentjouanne, submitted on August 26, 2026.

The tool, available at pairbook.io, lets users compare any two securities from its covered universe to see how closely their price movements track each other and how much their underlying holdings overlap. The overlap feature is particularly relevant for ETF investors who may hold multiple funds with significant shared positions without realizing it.

The HN submission provides no detail on the company's founding date, team size, funding status, or data sources. No investors, partners, or paying customers are named in the available sources.

Tools for portfolio overlap and correlation analysis exist within platforms like Morningstar and Portfolio Visualizer, as well as several brokerage research suites. PairBook's stated differentiator, based on the product description, is the breadth of its coverage — over 4,700 US-listed securities — and the pairing-focused interface. No direct competitive comparisons are made in the source material.

The Show HN post received 2 points and no comments at the time of submission, offering no additional user feedback or forward-looking detail about pricing, API access, or planned feature expansions.