What Is a 13F Filing? A Plain-English Guide

Every quarter, the world's largest investment managers hand the SEC a list of the US stocks they own. That list is the Form 13F, and it is the closest thing individual investors get to looking over the shoulder of Warren Buffett, Seth Klarman, or any other big institutional manager. The filings are public, free, and searchable. They are also widely misread, because a 13F shows far less than most people assume.

This guide walks through what a 13F actually is, who has to file one, what it contains, what it deliberately leaves out, and how to pull one up yourself on SEC EDGAR.

Where the 13F comes from

The requirement lives in Section 13(f) of the Securities Exchange Act of 1934, which Congress added in 1975. Lawmakers wanted a public record of what large institutions were doing with their growing share of the US stock market, partly so regulators and the public could see how concentrated institutional ownership was becoming. The SEC then created Form 13F as the disclosure vehicle.

The core idea has not changed in five decades: if you manage a large amount of money in US-listed stocks, the public gets to see your long positions once a quarter, with a lag.

Who has to file

The rule applies to institutional investment managers that exercise investment discretion over at least $100 million in so-called 13(f) securities. Both parts of that phrase matter.

An institutional investment manager is a broad category. It covers hedge funds, mutual fund advisers, pension funds, insurance companies, bank trust departments, endowments, and even corporations or individuals who manage portfolios for others. The label has nothing to do with being registered as an investment adviser; it is about exercising discretion over accounts holding the relevant securities.

13(f) securities are, roughly, exchange-traded US equities plus certain equity options and convertible bonds. The SEC publishes an official list of qualifying securities every quarter, so there is no guesswork about what counts. If a manager crosses the $100 million mark in those securities on the last trading day of any month during a calendar year, the filing obligation kicks in and covers the following four quarters.

That threshold was set in 1975 and has never been raised, which is one reason the number of filers has grown into the thousands. You can browse the most followed filers on the manager list.

The 45-day deadline

A 13F must be filed within 45 days after the end of each calendar quarter. In practice, most large managers file at or near the deadline, so the filings for a quarter ending March 31 land around mid-May.

This lag is the single most important thing to understand before acting on 13F data. A position you see in a fresh filing reflects a snapshot taken 45 or more days earlier, and the manager may have trimmed, added, or exited entirely since then. The snapshot is also just that: quarter-end only. A stock bought in early January and sold in late February never appears at all. Watching the activity feed around each deadline is useful precisely because everyone's snapshots arrive at once and can be compared.

What a filing contains

The heart of a 13F is the information table, one row per position. For each holding, the manager reports:

Field	What it tells you
Issuer name and class	The company and the type of security (common stock, a class of shares, a call or put)
CUSIP	The unique identifier for the security, which makes filings machine-readable
Market value	The fair value of the position as of quarter end
Shares or principal amount	How many shares (or, for convertibles, the principal) the manager holds
Put or call flag	Whether the row represents options rather than the shares themselves
Investment discretion and voting authority	Whether the manager decides on the position alone or shares that power, and who can vote the shares

Note what the table does not include: there is no purchase price, no cost basis, and no dates. When a tracker shows that a fund "bought" a stock, that is inferred by comparing two consecutive quarterly snapshots, not read directly from the filing.

Options deserve a special caution. A reported call position tells you the number of shares the options represent, but not the strike, the expiry, or whether the position is a bullish bet or one leg of a hedge. Treat option rows as a flag for further digging, not a signal on their own.

What a 13F leaves out

A 13F is a list of long US equity positions. It is not a full portfolio. Missing from every filing:

• Short positions. A fund that is short a stock discloses nothing about it. A manager could appear bullish on a sector in the 13F while being net short via undisclosed shorts.
• Cash. You cannot tell whether a manager is fully invested or sitting on a large cash pile.
• Bonds and other credit. Ordinary corporate and government bonds are outside the scope, with convertibles as the main exception.
• Most foreign-listed stocks. Shares traded only on non-US exchanges do not appear. US-listed ADRs of foreign companies generally do, which is why you will see names like Taiwan Semiconductor in filings.
• Private holdings. Stakes in private companies, real estate, commodities, and currency positions are all invisible.

For a long-only stock picker, the 13F may capture nearly the whole portfolio. For a global macro fund or a long-short equity fund, it can be a small and misleading slice. Always ask what kind of manager you are looking at before drawing conclusions.

Confidential treatment: the legal way to hide a position

Managers can ask the SEC for confidential treatment of specific positions, which delays public disclosure while a position is still being built. The classic use case is a large investor accumulating a stake who does not want copycats bidding the price up mid-purchase. Berkshire Hathaway has used this mechanism while quietly building major positions, which later appeared in amended filings once the SEC-approved confidentiality period ended. Requests are not rubber-stamped; the manager has to justify why disclosure would cause harm, and the omitted holdings must eventually be revealed.

Practically, this means a headline filing can be incomplete on the day it lands, and an amendment weeks or months later can reveal the position everyone was speculating about. You can see how a portfolio like Berkshire Hathaway's portfolio evolves across these filings and amendments.

13F-HR, 13F-NT, and amendments

Three variants of the form show up on EDGAR:

• 13F-HR (holdings report) is the standard filing containing the full information table. This is the one trackers and journalists read.
• 13F-NT (notice) contains no holdings. It says, in effect, "all of my reportable positions appear on another manager's filing." This happens with affiliated managers where a parent entity reports on behalf of subsidiaries.
• Amendments (13F-HR/A) either restate the whole report or add holdings that were left out, including positions that had confidential treatment. An amendment landing months after the original is often the most interesting filing of the bunch.

Some filings are combinations: a manager may file a holdings report covering part of its positions and note that the rest appear elsewhere.

The 2023 change: from thousands to whole dollars

For decades, 13F values were reported in thousands of dollars, so a value of "1,500" meant $1.5 million. Under amendments that took effect in January 2023, filers now report values in whole dollars. The same position today shows as "1,500,000".

This matters if you ever compare old filings to new ones, or work with raw EDGAR data across the boundary. Any dataset spanning 2022 and 2023 must normalize the two conventions, or every pre-2023 position will look a thousand times too small. Established trackers handle this for you, but it is a common trap in do-it-yourself analysis.

Looking up a 13F on EDGAR for free

Every filing is public on the SEC's EDGAR system at sec.gov. To find one:

1. Go to EDGAR's company search and type the manager's name (for example, "Berkshire Hathaway"). Searching by the manager's CIK number is more precise if you have it, since firms often have several similarly named entities.
2. Filter the filing list by form type "13F" to see holdings reports, notices, and amendments in date order.
3. Open a filing and view the information table. Modern filings include both a human-readable version and an XML file that is easy to parse programmatically.

EDGAR gives you the raw record, which is worth doing at least once so you know exactly what the source data looks like. The trade-off is convenience: EDGAR will not compare quarters, compute position changes, or aggregate across managers. That is the layer trackers add, such as a ranking of most bought stocks across all filers in a given quarter.

Reading 13Fs sensibly

A 13F is a delayed, long-only, US-equity snapshot of a portfolio, filed by managers who would often prefer you learn nothing from it. Used carelessly, it invites blind copying of trades that may already be closed. Used well, it is a research tool: a way to generate ideas, study how disciplined investors size and hold positions over years, and notice when several managers you respect independently arrive at the same stock. The filings are free and the record goes back decades. Few sources of investment education cost less.