A thematic ETF is meant to hold something different from the broad market. The data shows how much of that promise holds up. Across 379 funds with usable holdings data, the typical thematic ETF has 29% of its weight in stocks the S&P 500 already holds. That leaves a median active share, the portion of the portfolio that departs from the index, in the neighborhood of the numbers shown by theme below. Seventy-four of the 379 funds are more than sixty percent index names, meaning a majority of their weight sits in companies an S&P 500 tracker would already own.
The overlap varies widely by theme. Gold miners, silver miners, copper, and rare earth and critical materials funds show some of the lowest median shares in the S&P 500, at 5%, 2%, 10%, and 8% respectively, with active share readings of 100% or close to it. At the other end, energy security and critical technology shows a median of 86% in the S&P 500, and AI infrastructure and chips and semiconductors show 63% and 66%. Digital infrastructure and data centers sits at 62%. These are themes built from companies that, by weight, are already well represented in a standard index fund.
Fees do not track this distinction closely. Across 54 themes and 405 funds, the median fee is 0.60%, and when the fee is measured only against the part of each portfolio that differs from the S&P 500, the median fee for that difference is also 0.60%. Semiconductors, the theme with the second-highest median in-index share among the larger groups, carries a median fee of 0.30%, one of the lowest in the table. Space and cannabis, both with low or zero median S&P 500 weight, carry median fees of 0.80%. The relationship between how distinct a fund's holdings are and what it charges is not one-directional in this data.
The second table shows 139 pairs of funds, out of those examined, with portfolios more than half identical by weight; the 15 highest-overlap pairs are listed. EVMT and PDBA, both in electric vehicles and batteries, show 97% weight overlap. SOXQ and SOXX, both semiconductor funds, overlap 86%, with fees of 0.19% and 0.33%. AUAU and GDX, gold miners funds, overlap 84% at fees of 0.35% and 0.51%. In each of these pairs, holding both funds resembles holding one of them twice, with the fee difference the main distinction between the two positions.
One-year total returns and win rates against the S&P 500 are included by theme in the table, alongside these overlap and fee numbers, for themes where twelve-month data exists.
On the live desk, a reader can check the current in-index weight, active share, and fee numbers for any individual fund and theme, along with the up-to-date list of overlapping pairs.