Every quarter, some of the world's most sophisticated investors are required by law to reveal exactly which stocks they own. The document they file to do this is called a 13F, and it is one of the most closely followed data sources in professional and retail investing alike.
This guide explains what a 13F filing is, who has to file one, what it does and does not tell you, and — most importantly — how to use this information as part of a disciplined investment process.
What Is a 13F Filing?
A 13F, formally known as Form 13F-HR (Holdings Report), is a quarterly disclosure that institutional investment managers must file with the U.S. Securities and Exchange Commission (SEC). It lists every long equity position the manager held at the end of the quarter, along with the number of shares and the market value of each position.
The filing requirement comes from Section 13(f) of the Securities Exchange Act of 1934. Congress enacted it to provide transparency into the holdings of large institutional investors — the so-called "smart money" that moves markets.
Who Has to File a 13F?
Any institutional investment manager that exercises investment discretion over $100 million or more in Section 13(f) securities must file quarterly. This threshold captures:
- Hedge funds
- Mutual funds and asset managers
- Pension funds and endowments
- Insurance companies
- Banks and trust companies
This means that every major hedge fund — Berkshire Hathaway, Pershing Square, Scion Asset Management, Appaloosa Management, Baupost Group, and hundreds of others — is required to publicly disclose its equity holdings every single quarter. The filings are freely available on the SEC's EDGAR database and on platforms that aggregate and display them in a readable format.
When Are 13F Filings Due?
13F filings are due 45 days after the end of each calendar quarter:
| Quarter end | Filing deadline | |---|---| | March 31 (Q1) | May 15 | | June 30 (Q2) | August 14 | | September 30 (Q3) | November 14 | | December 31 (Q4) | February 14 |
The six-week period immediately following each deadline — when investors are poring over the newly filed disclosures — has become known informally as 13F season. It is one of the most active periods for research activity among value investors.
What Does a 13F Reveal?
Each 13F filing shows, for every disclosed position:
- The name of the issuer (the company)
- The CUSIP number (a nine-character identifier for each security)
- The share class
- The number of shares held as of the quarter-end date
- The market value of the position at quarter-end
- The investment discretion type (sole, shared, or none)
When you compare a manager's current filing to their previous one, you can derive:
- New positions — stocks added that were not in the prior quarter's filing
- Additions — existing positions where the share count increased
- Reductions — positions where the share count decreased
- Complete exits — positions that appeared in the previous filing but not the current one
These quarter-over-quarter changes are often the most valuable part of a 13F, as they reveal where a manager is actively deploying capital or reducing exposure.
What Does a 13F Not Reveal?
Understanding the limitations of 13F data is just as important as understanding what it contains.
Short positions are not disclosed. A manager's 13F shows only long equity positions. If a hedge fund is simultaneously long $500 million in one stock and short $300 million in another, only the long side appears in the filing.
Options and derivatives are partially disclosed. Equity options held at quarter-end appear in the filing, but the full derivatives picture is not captured.
The data is 45 days old. By the time you read a 13F, the underlying trades were made up to four and a half months ago. A manager who built a position in January will not have that position publicly visible until mid-May.
International stocks are excluded. 13F filings only cover U.S.-listed securities. A fund that is primarily invested in European or Asian equities will show a misleadingly small portfolio.
Cash and bonds are not included. The filing covers equity securities only. A manager holding 40% cash is not distinguishable from one holding 0% cash based on 13F data alone.
These limitations matter but do not eliminate the usefulness of the data. They simply define how it should be used — as a research input and idea-generation tool, not as a real-time portfolio tracker.
Why Investors Follow 13F Filings
The information quality of superinvestor holdings
The managers who attract the most attention in 13F data are not large pension funds or index funds — it is the concentrated value investors with long track records of outperformance. These are the investors who have consistently demonstrated superior analytical ability over decades.
When Warren Buffett's Berkshire Hathaway builds a new position, the market pays attention not because of the size of the trade but because of the signal it sends: one of the most experienced analysts in history has concluded that this company is worth owning at today's price.
The same logic applies to a small group of other managers — Seth Klarman at Baupost, Bill Ackman at Pershing Square, Michael Burry at Scion Asset Management — who have built reputations for deep, fundamental research and a willingness to take concentrated positions in out-of-favor companies.
New buys as the strongest signal
Of all the information available in a 13F, a new position — a stock that appears in the current quarter's filing but was absent from all prior filings — is typically considered the highest-conviction signal. It means a manager who has reviewed thousands of opportunities has chosen to deploy capital into this particular company for the first time.
Consensus holdings across multiple managers
When multiple independent managers with different styles and processes arrive at the same stock, it suggests a more broadly shared investment thesis. We track this on our superinvestors page, where you can see which stocks appear most frequently across all tracked portfolios — a useful starting point for generating new research ideas.
The 45-Day Lag: How to Think About Stale Data
The most common objection to using 13F data is the delay. By the time a filing is public, the information is weeks old. Does this make it useless?
For most value investors, the answer is no — for a simple reason. The managers whose 13F filings are worth following tend to be long-term investors who hold positions for years, not months. A position that Buffett initiated in January is unlikely to have been fully exited by May. The 45-day lag is a minor inconvenience for a manager whose average holding period is measured in years.
The lag matters more for managers who trade frequently or take short-term positions. For those managers, the 13F may provide little actionable information because the portfolio has already been significantly repositioned.
The practical approach is to focus on managers with low portfolio turnover — those who make few changes quarter to quarter — and to treat new positions and large additions as research ideas to investigate rather than trades to copy immediately.
How to Read a 13F Filing
The raw EDGAR filings are structured XML or plain-text documents that report positions using CUSIP numbers rather than ticker symbols. Working with them directly requires parsing the CUSIP-to-ticker mapping, which is non-trivial.
Platforms like this one do that work automatically, displaying each manager's holdings in a clean table with ticker symbols, position sizes, quarter-over-quarter changes, and the percentage of the portfolio each position represents.
When reviewing a manager's 13F, the key questions to ask are:
- What is new? New positions represent the manager's highest-conviction recent decisions.
- What was added significantly? Large additions to existing positions suggest growing conviction.
- What was completely exited? Full exits can be as informative as new buys, particularly if the manager held a position for many years before selling.
- How concentrated is the portfolio? A manager with 80% of their portfolio in five stocks holds their top ideas at very different conviction levels than one with 150 positions.
- What has not changed? Long-term core holdings that persist across many quarters reveal the manager's highest-conviction multi-year views.
Combining 13F Data With Insider Trading Data
13F filings and Form 4 insider filings are complementary data sources. One shows what professional investors with significant analytical resources believe, and the other shows what company management — with direct operational knowledge — is doing with their personal capital.
The combination is particularly powerful. When a superinvestor holds a significant position in a company and the company's executives are actively buying shares on the open market, two independent signals are pointing in the same direction. We surface this combination on our platform, where you can see insider buying activity specifically for companies held by the superinvestors we track.
For more on how to interpret insider buying signals, see our guide to SEC Form 4 and what insider purchases mean. And if you want to understand one of the strongest insider buying patterns specifically, our article on cluster buying explains why simultaneous purchases by multiple insiders at the same company carry especially strong informational value.
A Practical Workflow for Using 13F Data
The investors who extract the most value from 13F data tend to follow a consistent process:
Step 1: Identify relevant managers. Focus on a small number of investors whose process and philosophy you understand and respect. Following fifty managers produces noise. Following five to ten produces signal.
Step 2: Review new positions each quarter. When a manager you follow initiates a new position, put that company on your research list.
Step 3: Do your own analysis. Read the company's most recent annual report and last two or three earnings calls. Build a rough valuation. Understand what could go wrong. Do not simply copy the trade.
Step 4: Check for confirming signals. Does the company also show insider buying on Form 4? Has more than one tracked manager initiated a position? Does the stock appear in our consensus portfolio view?
Step 5: Size and monitor appropriately. If your analysis supports the thesis, size the position according to your own risk tolerance — not the manager's. Check back each quarter to see whether the manager is adding, holding, or reducing.
Summary
A 13F filing is a quarterly equity disclosure required of any institutional manager overseeing $100 million or more in U.S. securities. It reveals long stock positions, the number of shares held, and the market value of each position as of the quarter-end date.
The filings are publicly available, free to access, and updated every quarter. Their primary value lies in revealing what a small group of highly skilled, long-term investors own — providing retail investors with a systematic way to generate research ideas from the work of professionals who have spent decades refining their analytical process.
Used correctly — as a research input rather than a copy-trading system — 13F data is one of the most accessible edges available to the individual investor.