A look at what thematic ETFs actually hold, compared with the S&P 500, shows most of them are not far from it. Across 377 funds with usable holdings data, the typical, or median, thematic fund has 30% of its weight in stocks also held by the S&P 500. Seventy-four of the 377 funds have more than sixty percent of their weight in S&P 500 names. The remaining weight, what ETFIQ calls the difference from the index, is where a theme's distinct exposure sits.
The overlap varies a great deal by theme. Semiconductors funds have a median of 62% of weight in S&P 500 stocks, and AI infrastructure and chips funds sit at 63%. Energy security and critical technology is higher still, at 85%. At the other end, gold miners, silver miners, and cannabis funds show little overlap with the S&P 500: medians of 6%, 2%, and 0% respectively, alongside nuclear and uranium at 17% and miners and metals at 12%. Active share, the share of a fund's portfolio that differs from the index by weight, tracks the inverse of this pattern, running as high as 100% for several commodity-linked and metals themes and as low as 80% for broad innovation and megatrends and for metaverse and immersive tech.
Fees sit at a median of 0.60% across the 406 funds and 54 themes in the table. When fees are 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%. This number moves by theme: semiconductors funds show a median fee of 0.30% that becomes 0.40% once measured against the distinct portion of the portfolio, while AI infrastructure and chips funds hold at 0.70% either way. Cannabis funds show the reverse pattern, with a stated fee of 0.80% but a fee-for-the-difference of 0.60%, reflecting a theme with no measured overlap with the S&P 500 at all.
A separate pattern emerges in the pairs data. The piece identifies 131 pairs of funds whose portfolios are more than half identical by weight, meaning that holding both funds is, for that portion of the book, close to holding one of them twice. The listed pairs span agriculture, biotech, gold miners, semiconductors, space, cybersecurity, and water. The overlap numbers range from 100% weight overlap between PDBA and EVMT in agriculture down to 74% between SOXQ and SMH in semiconductors. Fees within these pairs sometimes differ by a wide margin: IBBQ carries a fee of 0.19% against IBB's 0.44% despite an 85% weight overlap, and SOXQ's 0.19% sits against SOXX's 0.33% at 82% overlap.
One-year total returns, where reported, range widely by theme, from semiconductors at +99.0% and genomics and gene editing at +74.3% down to internet and e-commerce at −16.2% and streaming and live entertainment at −23.4%. The number of funds beating the S&P 500 over one year also varies, from 9 of 9 in semiconductors and 8 of 8 in biotech to 0 of 14 in defense and 0 of 13 in internet and e-commerce.
Readers can check any fund's current in-index weight, active share, and fee numbers, along with the full pairs list, against the live desk.