How to Read a 13F Filing

What is a 13F filing?

Form 13F is a quarterly disclosure that the U.S. Securities and Exchange Commission (SEC) requires from every institutional investment manager overseeing at least $100 million in U.S. equity securities. This threshold captures a huge range of firms: hedge funds, mutual fund companies, pension funds, insurance companies, and family offices. The rule was introduced under Section 13(f) of the Securities Exchange Act of 1934, with the goal of giving regulators and the public visibility into who owns what across U.S. markets.

In practice, a 13F is a snapshot: a list of long equity positions, the number of shares held, and their market value, as of the last trading day of the calendar quarter. It says nothing about why a manager bought or sold, and nothing about positions taken and closed within the quarter itself, only what remained on the books at the cutoff date.

The 45-day filing lag, and why it matters

Managers are not required to file immediately. They have 45 calendar days after the end of the quarter to submit their 13F. That means a filing covering positions as of March 31 is not due until mid-May, a filing for June 30 is due by mid-August, and so on. By the time any 13F becomes public, the underlying data is already six to seven weeks stale, and it is entirely possible the manager has since added to, trimmed, or completely exited a position shown in the filing.

This lag is the single most important caveat when reading 13F data. A 13F tells you what a manager held at a point in the past, not what they hold today, and it should never be treated as a real-time signal to copy a trade.

What a 13F does NOT show

Understanding the blind spots of a 13F filing is as important as understanding what it discloses. A 13F excludes:

• Short positions. A manager betting against a stock through a short sale does not have to disclose it. A large 13F long book can sit alongside a short book that is completely invisible to the public.
• Non-U.S. securities. Only U.S.-listed equities are reportable. A global fund's European or Asian holdings, which can be the majority of its book, are absent from the 13F entirely.
• Cash and fixed income. Bonds, cash balances, and most money-market instruments are not part of the disclosure, so the "total value" of a 13F is not the manager's total assets under management.
• Most derivatives, except listed options. Puts and calls on reportable securities are disclosed, but many other derivative and swap exposures are not.
• The manager's intent. A 13F is a list of positions, not a letter of explanation. Any narrative about "why" a manager bought or sold is analysis layered on top of the raw filing, not part of the filing itself.

How to interpret quarterly moves

Most of the value in tracking 13Fs over time comes from comparing one quarter's filing to the previous one for the same manager. On every superinvestor profile on this site, we categorize the difference into four buckets:

• New buy, a CUSIP present this quarter that was absent from the prior filing: a brand-new position.
• Added to, share count increased versus the prior quarter: the manager grew an existing position.
• Trimmed, share count decreased but the position was not fully closed.
• Closed, a CUSIP present last quarter that is absent this quarter: the position was fully exited (or, in rare cases, converted into a different security class).

Two nuances worth keeping in mind: an increase in share count can sometimes reflect a stock split or a corporate action rather than an active purchase, and a "closed" position could simply mean the shares fell below the reporting threshold rather than being sold outright. Always sanity-check large moves against the position size before drawing conclusions.

Glossary: 13F terms explained

CUSIP

A nine-character alphanumeric code (Committee on Uniform Securities Identification Procedures) that uniquely identifies a U.S. security. 13F filings report holdings by CUSIP rather than by ticker, which is why matching a CUSIP to a familiar ticker symbol requires an extra lookup step.

13F-HR

The standard, complete quarterly 13F filing ("HR" stands for Holdings Report): the manager's full reportable long-equity portfolio as of quarter-end.

13F-HR/A

An amended filing. Critically, an amendment usually contains only the corrected or newly disclosed positions for that quarter, not the entire portfolio again, so it must be merged with the original filing to reconstruct the full, corrected picture.

Put / Call (in a 13F context)

Listed options positions are reportable on a 13F. A "Put" generally signals a bearish or hedging view on the underlying stock; a "Call" a bullish view, though options can also be used for hedging or income strategies unrelated to a directional bet.

Assets under management (AUM) threshold

The $100 million minimum in U.S. equity securities that triggers the 13F filing requirement. Below this threshold, a manager has no obligation to disclose holdings.

Superinvestor

An informal term (popularized by value-investing circles, tracing back to Warren Buffett's 1984 essay "The Superinvestors of Graham-and-Doddsville") for a small group of fund managers whose long-term track record is considered exceptional and whose 13F filings are closely watched by other investors.

Should you copy a superinvestor's trades?

13F data is a research input, not a trading signal. Beyond the 45-day lag and the blind spots described above, a position that makes sense for a multi-billion-dollar fund with a specific mandate, time horizon, and risk tolerance may not make sense for an individual investor at all. The most productive way to use 13F data is as a starting point for your own research: which businesses do the investors you respect keep coming back to, and why might that be, rather than a list of instructions to replicate.

Explore the data

fructus.finance tracks 13F filings for a curated group of superinvestors, updated as new filings become available on SEC EDGAR. Start with the full list of tracked managers, see which stocks the most investors agree on in the consensus view, or look up a specific U.S. stock's 13F ownership on its holdings page.