Wednesday, October 28, 2026
Data from SEC filings, checked daily
Public filings, plainly told
AboutMethodSourcesNewsletter
WallStPal · PDF guide
How Concentrated Is a Fund? Reading Top Holdings in a 13F · https://wallstpal.com/guides/fund-concentration-13f/ · saved 2026-10-28

About this page

A plain-English guide. Each guide ends with real examples and an "Explain it like I'm 13" section.

How to read it

Form 4
The form a company insider (officer, director or owner of more than 10%) must file with the SEC within two business days of buying or selling the company's shares.
13F
A quarterly list of U.S. stocks held by an investment manager with more than $100 million, filed within 45 days after each quarter ends.
STOCK Act
A 2012 law that requires members of Congress to report stock trades by themselves, a spouse or a dependent child within 45 days.

A real example

In January 2016, when bank stocks were falling, JPMorgan Chase CEO Jamie Dimon bought 500,000 JPMorgan shares with his own money, worth about $26 million. His Form 4 made the purchase public within days, and investors read it as a strong sign of confidence.

Explain it like I'm 13

This is the "how it works" part of the site, written so anyone can follow it.

Data from public SEC filings and congressional reports. Information, not investment advice. Check every number against the filing linked on the page.

Summarize with AIChatGPTClaudePerplexityGoogle AIGrokCopilot
Funds and 13FUpdated Oct 28, 2026 · 2 min read

How Concentrated Is a Fund?

Some funds put most of their money in ten stocks. Others spread it over thousands. The share held by the top 10 positions tells you how to read a fund's 13F, and whether copying it makes sense.

By · Founder and editor, WallStPal

The one number to check first

Add up the value of a fund’s ten largest positions and divide by the total on its 13F. That percentage tells you what kind of investor you are looking at. Every fund page on WallStPal shows it in the first line, under the fund’s name.

Three kinds of portfolios

  • Concentrated (top 10 above about 70%). A small number of large bets, each researched in depth. Every change matters, and a new position is a real decision.
  • Spread out (top 10 around 30% to 60%). Many positions, often including index ETFs. Single changes matter less, and the ETFs can be a way to hold the market while the fund’s real views sit in other instruments.
  • Very wide (top 10 below about 20%). Hundreds or thousands of positions, usually from computer-driven strategies that trade often. A single row tells you almost nothing about the manager’s view of that company.

Things that distort the number

  • Share classes. Alphabet class A and class C appear as two rows. Add them before ranking.
  • Options. Put and call rows show the value of the underlying shares, which can make a small position look huge.
  • What is missing. Short positions, bonds, foreign shares and private holdings are not in a 13F, so the “portfolio” is only the U.S. listed long part.

Examples

All figures below are from the funds’ 13F filings as shown on our fund pages.

Pershing Square, first quarter of 2026. Bill Ackman’s fund reported 11 holdings worth about $13.7 billion, and the top 10 made up 99.9% of the value. The largest, Brookfield, was about 17.6% on its own. When Pershing Square added Microsoft that quarter, the new position was over 15% of the portfolio. In a fund like this, one new row is a headline.

Berkshire Hathaway, second quarter of 2026. Berkshire reported 29 holdings worth about $299.3 billion, with the top 10 at 88.5%. Apple alone was about 22%. Berkshire’s 13F covers only its listed U.S. stocks. Its wholly owned businesses, such as its railroad and insurers, are not in the filing at all.

Renaissance Technologies, second quarter of 2026. Renaissance reported 3,140 holdings worth about $72.6 billion, and its top 10 made up only 12%. Its largest position, Nvidia, was under 2% of the total. That quarter it opened 566 positions and closed 639. Copying any single row from a filing like this would tell you nothing about a long-term view.

Bridgewater Associates, second quarter of 2026. Bridgewater reported 997 holdings, with the top 10 at 40%. Its two largest positions were S&P 500 ETFs: SPY at about 16.3% and IVV at about 9.2%. Most of Bridgewater’s trading is in bonds, currencies and futures, which a 13F does not show.

Explain it like I’m 13

Picture two kids with 100 marbles each. One keeps them in three bags: 50 blue, 30 red, 20 green. The other has 100 different marbles, one of each.

If the first kid swaps all the green marbles for yellow ones, that is a big decision. You’d want to know why. If the second kid swaps one marble, it hardly changes anything.

A 13F is a fund’s marble collection. Before you read anything into a change, check which kind of collector the fund is.

Ask Pal

Questions about this guide? Pal reads it with you and answers in plain English.

Related

WallStPal explains public filings. Nothing here is investment advice. Editorial policy · Corrections