What is inside an ETF: how to read holdings and spot concentration
An ETF's name describes a theme, and its holdings list shows what the money bought. The two can sit further apart than the label suggests. A fund with 500 positions can keep more than a third of its assets in ten companies, and a fund with 25 positions can keep almost a quarter in one.
The examples below come from the portfolio reports that funds file with the SEC, as shown on the stocks-llm ETF pages on September 21, 2026. Most of those reports describe portfolios as of June 30, 2026.
Where holdings data comes from
US funds report their full portfolios to the SEC on Form N-PORT. The form's instructions say the reports "must be filed with the Commission no later than 60 days after the end of such fiscal quarter", and that only the information for the third month of each fiscal quarter becomes public.
The public record is therefore a quarterly snapshot that can arrive two months late. $SPY filed its report for June 30 on August 28, which is 59 days later. On September 21 that report was still the newest one available, and the fund's page on stocks-llm marked it as 84 days old.
Fund sponsors publish sooner than that. The SEC's investor bulletin on ETFs notes that "Most ETFs post their portfolio holdings on their websites daily." The filed report has one format across every fund, which makes it the version you can compare, and the sponsor's website is where you check what has changed since.
Any holdings table has two dates worth finding before you read a single row. One is the day the portfolio describes, and the other is the day the report was filed.
Add up the top ten before you count the positions
The number of positions is the figure people quote most often, and it says the least about concentration. $SPY held 504 positions on June 30, and its ten largest added up to 36.4% of net assets. $VTI held 3,546 positions, seven times as many, and its ten largest added up to 32.0%.
Three thousand extra companies moved the top of the portfolio by about four points. Both funds weight companies by market value, so the same giants lead both lists. The investor.gov bulletin on index funds describes the mechanism: in a market-cap-weighted index, "securities with a higher market capitalization value account for a greater share of the overall value of the index."
Sector funds are far more concentrated than that. $XLE held 25 positions on June 30, with $XOM at 22.7% and $CVX at 16.1%. Those two companies made up 38.8% of the fund, and the ten largest reached 75.5%. $SMH held 26 positions with 70.2% in its top ten, and $XLK held 79 positions with 64.5% in its top ten.
A small-company fund sits at the other end of the range. $VB held 1,317 positions, and its ten largest came to 5.5%.
So the first thing to do with any holdings page is add up the ten largest weights. When that sum passes half of the fund, every other position, however many there are, shares the smaller half.
When one company takes two rows
Holdings are listed by security, and some companies have more than one share class. In the June 30 report for $SPY the name Alphabet Inc appears twice, in fifth place at 3.25% and in seventh place at 2.59%. Those rows are the company's two listed share classes, $GOOGL and $GOOG. Added together they come to 5.84%, which makes the company the third largest in the fund, ahead of $MSFT at 4.30%.
The row order understates an issuer whenever this happens, so merge the classes before you rank anything.
Weighting rules change the order
Two funds can own large, well-known companies and rank them differently, because the index rule differs. The index funds bulletin names the Dow Jones Industrial Average as a price-weighted index, and says that in such an index "the price per share will determine the weight of a security."
$DIA tracks that average. In its report for July 31, 2026, the largest of its 30 positions was $GS at 11.5%, and the ten largest came to 55.3%. $GS is at the top of that list because its share price is high. It does not appear among the ten largest positions of $SPY, where weight follows market value.
Checking whether two funds differ
Holdings are also how you find out whether two funds give you different exposure. $QQQ held 105 positions on June 30, against 504 for $SPY, and eight of its ten largest rows also sat in the top ten of $SPY. $NVDA was 7.60% of one fund and 7.52% of the other, and $AAPL was 6.67% and 6.59%.
Someone who owns both funds holds the same large technology companies twice, at close to the same weights.
$SCHD shows the opposite case. Its report for May 31, 2026 was led by $QCOM at 6.7%, $TXN at 5.9% and $UNH at 5.1%, and none of its ten largest positions appeared in the top ten of $SPY.
Rows that are not stock picks
Some lines in a filed portfolio are there for operational reasons. On June 30 the largest single row in $IWM, a fund of about two thousand small companies, was shown under the issuer name BlackRock Funds III at 17.0% of net assets. The filing identifies it as BlackRock Cash Funds: Institutional, SL Agency Shares, which is a money market fund. The stocks in the same filing already came to 99.8% of net assets, and the fund reported total assets of $97.1 billion against net assets of $83.0 billion.
The prospectus for that share class says it is offered to funds BlackRock advises and to funds that have directed its securities lending agent "to invest securities lending cash collateral in SL Agency Shares of the Fund." A row like that carries no information about which small companies the fund prefers, so leave it out when you rank the holdings. The second row of $IWM was 0.38%.
Funds that hold a commodity need a different reading. $GLD does not file Form N-PORT. It reports its gold in the quarterly 10-Q it files as a trust, and on June 30 its holdings list had one line, 32,314,200 troy ounces of gold bullion.
Limits
Filed holdings are dated snapshots, and a fund can trade every day between them. Weights are the fund's own reported percentages of net assets, which is why a list can add up to more than 100% when a fund carries lending collateral. Fund pages on stocks-llm show what the SEC filing says, with its report date and filing date, and list the positions added and removed since the previous report. They carry nothing newer than the latest filing. The ETF list covered 48 funds on September 21, 2026, and it is a selection, so a fund missing from it may be outside the catalog.
This article is for information only and is not financial or investment advice. A holdings list is a starting point for research. Check the sponsor's current holdings and the fund's prospectus before making an investment decision.