How to Track What Billionaire Investors Are Buying (Using SEC EDGAR Data)

Warren Buffett just filed his latest 13F. Cathie Wood reshuffled her portfolio. A CEO quietly sold $50M worth of shares. All of this is public data — the SEC requires it. But actually getting to it programmatically? That's where most people give up. SEC EDGAR's website is a maze of SGML files, inconsistent formatting, and nested folders. I spent weeks parsing it and built an API so others don't have to. Here's what I learned and how to use it. What Are 13F Filings? Every institutional investment manager with over $100M in assets must file a 13F-HR with the SEC each quarter. This filing lists every equity position they hold — stock name, number of shares, and market value. This is how you find out what Berkshire Hathaway, Bridgewater, or Renaissance Technologies actually own. The Problem with Raw EDGAR Data If you go to sec.gov/cgi-bin/browse-edgar and try to pull 13F data, you'll find: Filings are in XML/SGML with inconsistent schemas across years No unified search across companies and