Learn · Last updated August 22, 2026
What Is a 13F Filing? A Plain-English Guide
A 13F filing is a quarterly report that large institutional investment managers must file with the U.S. Securities and Exchange Commission, disclosing the U.S.-listed stocks they hold. It is the main public window into the portfolios of hedge funds and asset managers like Berkshire Hathaway and Bridgewater Associates.
The form's official name is Form 13F, required under Section 13(f) of the Securities Exchange Act of 1934 — a provision Congress added in 1975. The SEC publishes every filing for free on its EDGAR system.
Who has to file a 13F?
Any institutional investment manager that exercises investment discretion over at least $100 million in “13(f) securities” — roughly, U.S. exchange-traded stocks, ETFs, and certain options and convertible notes — must file. The SEC publishes the official list of 13(f) securities each quarter.
“Institutional investment manager” is broad: hedge funds, mutual fund companies, pension funds, insurance companies, banks, and family offices all file. That's why the filer universe is large — roughly 9,000+ managers file with holdings every quarter — even though public attention focuses on a few dozen famous names.
When are 13F filings due?
A 13F must be filed within 45 days after the end of each calendar quarter:
| Quarter ends | Filing deadline (approx.) |
|---|---|
| March 31 | May 15 |
| June 30 | August 14 |
| September 30 | November 14 |
| December 31 | February 14 |
(When a deadline falls on a weekend or holiday, it shifts to the next business day.) Most famous managers file on or near the deadline, which is why “13F season” produces a burst of financial news four times a year.
What's in a 13F filing?
The heart of a 13F is its information table — one row per position, each reporting:
- Issuer name — the company held (e.g., “APPLE INC”).
- CUSIP — the security's identifier.
- Value — the position's market value at quarter-end. (Historically reported in thousands of dollars; since a 2023 SEC change, in whole dollars — a convention switch that still trips up data providers.)
- Shares held and share class.
- Investment discretion and voting authority.
- Whether the position is shares or certain put/call options.
A filing is a snapshot as of the last day of the quarter — not a trade log. You learn what a manager held on, say, June 30; you do not learn when during the quarter they bought it or what they paid.
What a 13F does NOT show
This is the part most coverage gets wrong. A 13F omits:
- Short positions — only long positions in 13(f) securities are reported.
- Cash and cash equivalents.
- Foreign-listed stocks (unless they trade in the U.S. as ADRs).
- Most bonds, private holdings, real estate, and other non-13(f) assets.
- Trade timing and cost basis — snapshots only.
- Anything after quarter-end. Combined with the 45-day window, a position you read about today may have been sold weeks ago.
A famous fund can therefore look wildly different in its 13F than in reality — a long/short fund's 13F shows only half its book.
How to read a 13F (5 steps)
- Find the filing. Search the manager's name or CIK on SEC EDGAR, or use a tracker that parses filings for you.
- Check the form type. 13F-HR is the holdings report; 13F-NT is a notice that another filer reports the holdings; /A suffixes are amendments.
- Open the information table and sort by value to see the largest positions.
- Compare against the previous quarter. The single most useful signal is the change: new positions, exits, and size increases or decreases. The filing itself doesn't show changes — you (or your tools) must diff two quarters.
- Mind the caveats. Confidential treatment can delay some positions; multiple entities of one manager may file separately; options positions can invert the apparent bet.
Why investors track 13Fs
- Idea generation: a concentrated new position from a respected value investor is a research lead (not a buy signal).
- Conviction and trend reading: rising or falling position sizes across quarters show how a manager's thesis is evolving.
- Consensus mapping: aggregating hundreds of filings reveals what institutional investors collectively added or exited in a quarter.
- Accountability: 13Fs are how journalists and academics verify what famous managers actually held versus what they said.
Limitations and criticisms
Taken seriously, 13F data has real limits: it is up to 45 days stale at publication; it shows longs only; snapshots hide intra-quarter trading (“window dressing” around quarter-end is a known critique); and copying trades from filings performs poorly for high-turnover managers. It works best for low-turnover, concentrated, long-oriented managers — which is precisely why Berkshire Hathaway's 13F gets so much attention.
13F vs 13D vs 13G
| Form | Trigger | What it tells you | Timing |
|---|---|---|---|
| 13F | Manager has ≥$100M in 13(f) securities | Full long U.S.-equity portfolio, quarterly snapshot | Within 45 days of quarter-end |
| 13D | Investor acquires >5% of a company with activist intent | A stake in one company + intentions | Within 5 business days of crossing 5% |
| 13G | >5% stake, passive intent | A stake in one company, passive | Shorter/periodic schedules depending on filer type |
13D/13G filings are event-driven and company-specific; the 13F is the portfolio-wide quarterly disclosure.
Frequently asked questions
Where can I read 13F filings for free?
On the SEC's EDGAR system — every filing, at no cost, in raw form. Trackers like Whale's Nest parse those same filings into portfolios, quarter-over-quarter changes and alerts; the underlying data is always the SEC's.
Do 13F filings show short positions?
No. Only long positions in 13(f) securities are reported. A fund's short book, cash, and most non-U.S. holdings are invisible in its 13F.
How reliable is 13F data?
Filings are legal disclosures, but errors happen — the SEC does not verify contents before publication, value-reporting conventions changed in 2023, and a small share of filings each quarter contain unit mistakes. Serious data providers normalize and sanity-check filings against the SEC's own extractions.
Is a 13F useful if it's 45 days old?
For trade-copying of fast traders, no. For following low-turnover managers who build positions over quarters — the Buffetts and Ackmans — the lag matters far less, because their holdings change slowly.
What is a 13F-NT?
A “notice” filing: the manager's holdings are reported on another filer's 13F (common in multi-entity firms), so the notice filer's own report is intentionally empty.
Can managers hide positions from their 13F?
Temporarily, yes: the SEC can grant confidential treatment, letting a manager delay disclosing positions still being built. The positions appear in a later amendment. Berkshire Hathaway has used this repeatedly.
Sources: SEC — Form 13F FAQ · SEC official 13(f) securities lists · SEC EDGAR. Whale's Nest is an independent product and is not affiliated with the SEC. Nothing here is investment advice.
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