How much of a theme was already the index, 2026-Q2

The problem

You buy a theme because you want exposure to something the index does not give you. Whether it does is a question about holdings, and holdings are filed quarterly in a form nobody reads. So the fund is sold on the story and bought on the story, and nobody publishes the one number that would settle it: how much of this did I already own.

There is no answer for the category. There is an answer for each fund, and across funds sold under the same word it runs the whole way from none of it to all of it.

What happened in the second quarter of 2026

The median fund had 32.5 percent of its money in companies already in the S&P 500. At the tenth fund that number was 0.0 percent and at the ninetieth 72.8. The median fee was 0.56 percent.

The defense of these funds is in the second number, and it is a real one. Even where a fund holds index companies it does not hold them in index proportions: the median overlap measured by weight is 2.50 percent. So these are not the index in disguise. They are the index’s companies in very different sizes, which is a different thing and is what a buyer is actually paying for.

Over the quarter itself, 111 of the 227 finished behind the S&P 500 and 116 ahead, by a median of 0.47 percentage points.

The most index-like fund in the second quarter of 2026 was AIEQ, Amplify AI Powered Equity ETF, filed under artificial intelligence. 100.0 percent of its money was in companies that were already in the S&P 500, and it weighted them differently enough that only 63.7 percent of its book overlapped the index by weight. Those two numbers together are the whole question a thematic buyer should be asking, and neither of them is on a fact sheet.

One of 227 funds, holdings dated Jun 30, 2026.

What the fee does not know

Split the funds by how much of the index they hold and the fee barely moves. A buyer getting almost none of the S&P 500 and a buyer getting three quarters of it pay within a fraction of a point of each other, and neither was told which one they were.

By share of the fund already in the S&P 500, 2026-Q2. Source: ETFIQ.

The return column is what happened in one quarter and is not a finding about index-likeness. The funds holding more of the index did better here because the large companies in it rose; a quarter where they fall reverses the whole column. The fee column is the one that does not depend on the quarter.

The funds that are most nearly the index

Ten funds whose money is almost entirely in S&P 500 companies, with the weight overlap beside it. A high first number and a low second one is a fund holding the index’s companies in its own proportions, which is the thing worth paying for. A high first number and a high second one is something else.

Most of the fund already in the S&P 500, 2026-Q2. Source: ETFIQ.

Every fund, 2026-Q2

All 227 funds, most of the index first. Holdings are each fund’s own filing for a date inside the quarter. Returns are total returns over the same days. Numbers in percentage points.

The two ends, gap.

How this was computed

Two kinds of fact, and they are kept apart. The returns are each fund’s total return across the quarter on split and distribution adjusted closes, against the S&P 500 over the same two dates, from Tiingo. They are exact and they do not move.

The holdings are read from each fund’s own filing, and a filing has a date. A fund is in this study only if its book was filed for a date inside the quarter: the books here run from Apr 30, 2026 to Jun 30, 2026. A book from after the quarter is a fact about a later one and a book from long before it is a fact about an older one, and either published beside an exact return would be the two halves of this page describing different three-month periods. "In the index" is the share of the fund’s equity weight held in companies that are in the S&P 500 at all; "by weight" is how much of the book overlaps the index at the same weights. Both come from the same function the category page uses.

What was left out, and why

A fund that did not trade the whole quarter has no quarter. A fund whose price is unchanged on more than half its days is a quote rather than a trade. And a fund with no book filed for a date inside the quarter can have its return measured but not its overlap, so it is counted here rather than published with one number missing.

Funds excluded and why, 2026-Q2. Source: ETFIQ.

Where the quarter starts

Each return here runs from the first close inside the quarter to the last, so the move on the quarter’s first trading day is left out. An issuer’s quarterly number starts at the prior quarter-end close, so the two can differ by that day’s move, which for a leveraged or single-stock fund can be several points.

Check it yourself

Every number above is in the file below, fund by fund, with the excluded funds and the reason for each. The data ETFIQ computed is free to use, including commercially, with attribution to ETFIQ and a link; the terms a fund row restates are its issuer's and stay under its owner's terms.