How to Track What Hedge Funds Are Buying and Selling (Using SEC 13F Data)

Every quarter, the largest institutional investors in the US are required by law to tell the SEC exactly what they're holding. These filings — called 13Fs — are public record. Warren Buffett's latest moves, Bridgewater's macro bets, Renaissance's quant positions: it's all there, 45 days after quarter-end, sitting in a government database. The problem is that database is genuinely painful to work with. This post explains what 13F filings contain, why developers care about them, and how to actually pull clean, structured data from them in Python. What Is a 13F Filing? Section 13(f) of the Securities Exchange Act of 1934 requires institutional investment managers with more than $100 million in assets under management to disclose their equity holdings quarterly. The filing deadline is 45 days after each quarter ends (so Q4 data arrives by mid-February). What's included: Every equity position (stocks, ETFs, call/put options) worth more than $200,000 or 10,000+ shares Share count and market