General information about public filing rules, not legal or investment advice. Check the primary sources below before relying on any detail.
What Form 13F is
Form 13F is filed under Section 13(f) of the Securities Exchange Act of 1934. It is a quarterly report of the holdings of institutional investment managers: the securities they hold, how many shares, the value, and whether the manager has investment discretion and voting authority over them. It is the source behind WaveMan's fund pages and the institutional ownership section of company pages such as Apple and Microsoft.
Who has to file
An institutional investment manager that uses the mail or any means of interstate commerce in its business, and exercises investment discretion over $100 million or more in Section 13(f) securities, must file Form 13F. According to the SEC staff FAQ, institutional investment managers include investment advisers that manage private accounts, mutual funds or pension assets, banks and bank trust departments, insurance companies, broker-dealers, and corporations and pension funds that manage their own investment portfolios. A natural person investing only for their own account is not one.
When the $100 million test is measured
The threshold is measured at the end of each month. According to the SEC staff FAQ, a manager must file if the securities it manages had a total fair market value of $100 million or more on the last trading day of any month of a calendar year. The first 13F is then due for the December quarter of that year, and filing continues for the following March, June and September quarters even if the value later falls below $100 million.
When 13F reports are due
A Form 13F is due within 45 days after the end of each calendar quarter. Holdings are reported as of the last day of the quarter, so a 13F is always a view of the past: a filing made on the last allowed day describes a portfolio that is about six weeks old, and the manager may have traded since.
Which securities are reported
The Official List
Only Section 13(f) securities are reported, and the SEC publishes an Official List of Section 13(f) Securities each quarter. The staff FAQ says securities that are not on the Official List should not be reported. According to the FAQ, the list mainly contains US exchange-traded stocks, shares of closed-end funds and exchange-traded funds, and certain convertible debt securities, equity options and warrants. Open-end mutual fund shares are not on it.
What a 13F leaves out
- Short positions. The FAQ says managers should not include short positions, and should not net them against long positions. A 13F shows only one side of a hedged book.
- Securities off the Official List, such as open-end mutual fund shares.
- Positions under confidential treatment. The SEC can grant confidential treatment for some holdings for a set period. When it expires or is denied, the manager amends the 13F to add them.
- Anything after the quarter end. A 13F is a snapshot, not a trade log.
What each row of a 13F tells you
A 13F Information Table lists each reported security with its value and size, and, according to the SEC staff FAQ, the type of investment discretion (sole, shared-defined or shared-other) and the voting authority (sole, shared or none). The FAQ notes that voting authority is separate from investment discretion, so a manager can direct an investment without voting it.
The distinction matters when reading ownership. A manager with investment discretion decides whether to buy or sell a position. A manager with voting authority decides how the shares are voted at shareholder meetings. Some managers have both, some only one, and a 13F reports each separately rather than treating ownership as a single figure.
Because the same company can appear on many managers' filings, adding up 13F rows across managers gives a rough picture of how much of a company is held by large institutions. It is rough for the reasons above: the lag, the missing shorts and the confidential positions.
13F, 13D and 13G: how they differ
All three involve large holders, but they answer different questions:
- Form 13F is about the manager: every covered position, large or small relative to each company, once per quarter.
- Schedule 13D or 13G is about one company: it is triggered when any holder, institutional or not, owns more than 5 percent of a class, and it has its own, faster deadlines.
- Form 4 is about insiders, including owners of more than 10 percent, and is due within two business days of a trade.
A large fund can therefore appear in all three: in its own quarterly 13F, in a 13G for a company where it crossed 5 percent, and in Form 4 if it crossed 10 percent.
How to read a 13F without overreading it
- Compare quarters. The change in a position from one quarter to the next is usually more informative than the position itself.
- Remember the lag. Up to 45 days pass after the quarter ends before the report is due.
- Remember what is missing. No shorts, no cash, nothing off the Official List. A 13F is not the whole fund.
- Value is reported, not performance. A 13F does not show what the manager paid for a position or when it was bought within the quarter.
- Index managers hold everything. A huge position from an index fund manager says little about conviction.
To explore 13F data, start with the fund pages, look at activist stakes for 13D and 13G filings, or open a company such as Nvidia to see who reported holding it.
Frequently asked questions
Who has to file Form 13F?
An institutional investment manager that exercises investment discretion over $100 million or more in Section 13(f) securities, measured on the last trading day of any month of a calendar year.
When is Form 13F due?
Within 45 days after the end of each calendar quarter. The first filing is due for the December quarter of the year in which the manager first meets the $100 million threshold.
Does a 13F show short positions?
No. The SEC staff FAQ says managers should not include short positions on Form 13F and should not net them against long positions.
What securities are reported on Form 13F?
Only securities on the SEC's quarterly Official List of Section 13(f) Securities, which mainly contains US exchange-traded stocks, closed-end fund and ETF shares, and certain convertible debt, equity options and warrants. Open-end mutual fund shares are not on the list and are not reported.
Sources
Every rule, deadline and threshold above was checked against these primary documents on 2026-10-12:
- SEC Division of Investment Management, Frequently Asked Questions About Form 13F
- 17 CFR 240.13d-1, filing of Schedules 13D and 13G
- Securities Exchange Act of 1934, Section 16 (15 U.S.C. 78p)
More guides
- What Is SEC Form 4? Insider Trading Filings Explained
- Form 4 Transaction Codes: What P, S, A, M, F, G and the Rest Mean
- Form 144 Explained: The Notice Filed Before a Rule 144 Sale
- Schedule 13D vs 13G: Who Files Which, and the 2024 Deadlines
- The STOCK Act: How Members of Congress Disclose Their Stock Trades