What Is a 13F Filing?
A plain-English guide to institutional holdings data — what it shows, what it cannot show, and how to use it without over-interpreting.
The basics
Form 13F is a quarterly report that the U.S. Securities and Exchange Commission (SEC) requires from institutional investment managers with over $100 million in assets under management. Each quarter they must disclose their long U.S. equity positions — the stocks they hold, how many shares, and the reported market value.
Every position is reported as of the last trading day of the quarter. Famous filers include Berkshire Hathaway, Bridgewater Associates, Citadel, Renaissance Technologies, ARK Invest and large asset managers such as BlackRock.
The 45-day delay
Filings are due within 45 days after quarter end:
- Q1 (Mar 31) → due by May 15
- Q2 (Jun 30) → due by Aug 14
- Q3 (Sep 30) → due by Nov 14
- Q4 (Dec 31) → due by Feb 14
That means the data on this site is always a snapshot of the past. By the time you see a position, the fund may have already changed it.
What 13F does not show
- Short positions — only long (bullish) holdings are reported.
- Cash, bonds and most non-U.S. securities — only U.S.-listed equities and certain options/convertibles appear.
- Intraday or real-time activity — a position marked unchanged may have been traded heavily inside the quarter.
- Index funds are not stock picking — mega-managers like BlackRock or Vanguard hold what their index products must hold. That is why many of our rankings focus on active managers.
How to read quarterly changes
This site tags each position change by comparing with the fund's previous filing:
- New — first time the stock appears in the fund's filing.
- Add — share count increased by more than 0.5%.
- Reduce — share count decreased by more than 0.5%.
- Hold — essentially unchanged (within 0.5%).
- A dash in a history matrix means the position was fully exited that quarter.
Limitations — read before drawing conclusions
- Data is delayed up to 45 days and refreshed quarterly, not continuously.
- Reported value uses the fund's own valuation — portfolios with options or foreign listings can show inconsistencies.
- A single quarter's change is noise-prone; multi-quarter trends (see our consecutive accumulation ranking) are more meaningful.
- Copies of a fund's strategy (e.g. 13F mirrors of the same manager) can double-count conviction.
- Nothing on this site is investment advice. Treat every list as a research starting point and verify against the original SEC filings.
Where to go next
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