13F Filings: A Developer's Guide to the SEC's Best Free Dataset

What Are 13F Filings? Every institutional investor managing $100M+ in qualifying US equities must file Form 13F with the SEC quarterly. This includes hedge funds, mutual funds, pension funds, banks, and insurance companies. For developers and quant researchers, this is one of the best structured, free datasets in finance. The Data Structure { "filer" : "Berkshire Hathaway" , "cik" : "0001067983" , "period" : "2025-12-31" , "holdings" : [ { "name" : "APPLE INC" , "cusip" : "037833100" , "value" : 73500000000 , "shares" : 300000000 , "put_call" : null } ] } Filing Timeline Q1 (Jan-Mar) : Due by May 15 Q2 (Apr-Jun) : Due by August 15 Q3 (Jul-Sep) : Due by November 15 Q4 (Oct-Dec) : Due by February 15 45-day lag is the key limitation. What's Included ✅ Long equity positions ✅ Exchange-traded options (puts and calls) ✅ Convertible bonds and notes What's NOT Included ❌ Short positions ❌ Non-US securities ❌ Private equity/debt ❌ Cash and bonds ❌ Real-time updates Data Sources SEC EDGAR — raw