What a 13F is
The SEC's rule is simple. Institutional investment managers that exercise investment discretion over $100 million or more in Section 13(f) securities must file Form 13F (>SEC 13F FAQ).
Section 13(f) securities include U.S. exchange-traded stocks, shares of closed-end funds and ETFs. Mutual fund shares are not on the list.
Each filing lists the holding, share count, reported value, and whether a line is a put or call.
What a 13F leaves out
This is where most copy-trading goes wrong. The form is a partial picture by design.
| Shown on a 13F | Not shown on a 13F |
|---|---|
| Long positions in U.S.-listed stocks and ETFs | Short stock positions ("You should not include short positions") |
| Puts and calls the fund holds | Options the fund wrote ("You should not report put or call options that you write") |
| Share counts and reported value on the quarter's last day | Trades made during the quarter or after it ended |
| Which manager filed | Entry prices, cost basis, strikes or expiries |
Source for the quoted rules: >SEC 13F FAQ.
Options create a second trap. A 13F reports options by the value of the underlying shares. Michael Burry's final Scion filing showed $912 million in Palantir puts, while Burry said his actual exposure was about $9.2 million (>Sherwood News). If you copy by dollar weight, a fund's option lines can look far bigger than the money behind them.
The 45-day lag, in numbers
The SEC says each filing "is due within 45 days after the end of the calendar quarter." Counting 45 days from each quarter end gives these dates:
| Quarter ends | 45th day after quarter end |
|---|---|
| March 31 | May 15 |
| June 30 | August 14 |
| September 30 | November 14 |
| December 31 | February 14 |
Now take a trade the fund made early in the quarter. Say a manager bought on April 1, 2026 and filed on August 14, 2026. The trade becomes public 135 days after it happened (29 days left in April, plus 31, 30 and 31 for May through July, plus 14 in August).
Some managers file sooner. Scion filed its September 30, 2025 report on November 3, 2025, which is 34 days (>SEC EDGAR). Pershing Square's Q2 2026 report used the full window.
Worked example: Ackman's Q2 2026 filing
Pershing Square's Q2 2026 filing shows two practical problems: the lag, and a change in who files.
The filer changed. For the June 30, 2026 quarter, Pershing Square Capital Management filed a 13F notice instead of a holdings report. The notice says: "Holdings of this reporting manager are now included in the report of its public parent company," which is Pershing Square Inc. (>SEC EDGAR). A tracker still watching the old filer would find no holdings at all.
The portfolio. Pershing Square Inc.'s 13F for June 30, 2026 lists 15 lines with a total reported value of about $19.47 billion (>SEC EDGAR). The largest positions, with weights we calculated from the filing:
| Holding | Reported value | Weight |
|---|---|---|
| Uber | $2.48B | 12.7% |
| Brookfield Corp | $2.45B | 12.6% |
| Microsoft | $2.32B | 11.9% |
| Amazon | $2.04B | 10.5% |
| Howard Hughes Holdings | $1.99B | 10.2% |
| Restaurant Brands | $1.87B | 9.6% |
| Meta Platforms | $1.80B | 9.2% |
| Visa | $1.12B | 5.8% |
| Mastercard | $1.09B | 5.6% |
| S&P Global | $1.06B | 5.4% |
| Netflix | $0.93B | 4.8% |
What changed from Q1. We compared these holdings with the two Q1 2026 filings, both filed May 15, 2026 (>Pershing Square Capital Management, >Pershing Square Inc.). Visa, Mastercard, S&P Global and Netflix are new. Alphabet, a $99 million line in Q1, is gone. Amazon fell from 11,451,981 shares to 8,563,857, a 25.2% cut.
Part of the jump in total value comes from the change in filer, so don't read the whole increase as new buying.
Put the timing together and here is what a copier saw. A position like Netflix, bought at some point between April 1 and June 30, became public on August 14. The filing does not say when in the quarter the shares were bought or at what price. Anyone copying on August 14 paid August prices.
A practical way to use 13Fs
Copying line for line ignores everything above. These steps account for it.
- Check two dates on every filing. The period of report tells you when the snapshot was taken. The filing date tells you when the public saw it.
- Track changes, not the snapshot. New positions, exits and big trims (like the Amazon cut) show what the manager decided during the quarter. A static list does not.
- Separate shares from options. Option lines are reported at underlying value. Size them accordingly or leave them out.
- Follow the filer. Reorganizations happen. If a fund files a 13F notice, find the entity that now reports its holdings.
- Check the chart before acting. A stock can move a long way in 45 days. Compare today's price and trend with the quarter-end snapshot.
- Watch for frozen books. Burry's Scion stopped filing after deregistering in November 2025, so its last 13F will never be updated.
How to use it on the Loomi.Ai Desk
Hedge Fund Legends is part of the Loomi.Ai Desk, listed on the pricing page as "Backtest Lab + Hedge Fund Legends" and on the plan card as "Top 7 Hedge Fund Portfolios to clone." The Desk costs $8/mo intro, then $20/mo.
Loomi's own framing matches this article: "Legends organizes disclosed fund holdings. Check the filing date and reporting period before comparing them with your own watchlist; a reported portfolio is not a live view of a fund's trades."
The Burry book is a case in point. It is frozen at Scion's last filing for September 30, 2025.
To close part of the lag, pair a fund's disclosed names with Desk tools that update more often. Check a name's trend on the RSI-2 signal engine or Ascent's stage read. Look at current options activity on the flow scanner. Compare price with dealer gamma levels on the GEX map. The 13F tells you what a manager liked last quarter. The Desk shows what the stock is doing now.
Put the research to work on your Desk
Explore the tools behind the research, compare the available access, or open your Desk if you already have an account.
FAQ
How long after the quarter do hedge funds file 13Fs? Up to 45 days after the calendar quarter ends, per the SEC. That means May 15, August 14, November 14 and February 14.
Can you make money copying hedge funds with 13F filings? This article does not test that, and we have not backtested a 13F copy strategy. What the data shows is the delay: a copier sees positions weeks or months after the fund took them.
Do 13F filings show short positions? No. The SEC tells filers not to include short positions. Options the fund wrote are also excluded.
Where do I find a fund's 13F? On SEC EDGAR, under the filing manager's name. Check whether the fund has changed reporting entities.
Loomi.Ai provides educational market research, not financial advice. 13F data is historical and delayed, and you are responsible for your own trading decisions.
Sources
- >Frequently Asked Questions About Form 13F, SEC
- >Pershing Square Inc. 13F-HR, period 6/30/2026, filed 8/14/2026, SEC EDGAR
- >Pershing Square Capital Management 13F-NT, period 6/30/2026, filed 8/14/2026, SEC EDGAR
- >Pershing Square Capital Management 13F-HR, period 3/31/2026, SEC EDGAR
- >Pershing Square Inc. 13F-HR, period 3/31/2026, SEC EDGAR
- >Scion Asset Management 13F-HR, period 9/30/2025, SEC EDGAR
- >Michael Burry de-registers his hedge fund, Scion Asset Management, Sherwood News