Thematic ETFs are often described as a way to step outside the broad market, but the holdings tell a more mixed story. Across 381 funds with usable data, the typical thematic ETF holds 30% of its weight in stocks already found in the S&P 500. Some themes lean heavily on familiar names. Energy security and critical technology shows a median of 85% overlap, and AI infrastructure and chips sits at 63%, with digital infrastructure and data centers and semiconductors both near 62%. Others diverge further from the index. Cannabis shows 0% overlap, silver miners 2%, and gold miners 6%, meaning these portfolios are built almost entirely from names the S&P 500 does not hold. Across all funds, 74 of 381 carry more than sixty percent of their weight in index names.
Fees sit at a median of 0.60% across the 409 funds and 54 themes covered. When the comparison is narrowed to just the portion of each portfolio that differs from the S&P 500, the median fee for that distinct slice is also 0.60%, meaning the cost of the non-index part of a typical thematic fund matches the fee charged on the whole fund. This pattern holds in most themes, though a few show a gap: cannabis funds charge a median 0.80% overall but 0.60% on the different part, while artificial intelligence, broad innovation and megatrends, digital infrastructure and data centers, and several smaller themes charge slightly more on the differentiated slice than on the fund as a whole.
Active share, a measure of how much a fund's weights differ from the index, reaches 100% in themes like gold miners, nuclear and uranium, space, rare earth and critical materials, agriculture, lithium and battery metals, cannabis, and others, meaning no weight-for-weight overlap exists with the S&P 500 reference book. Lower active share numbers appear in artificial intelligence (80%), quantum computing (84%), semiconductors (85%), and digital infrastructure and data centers (88%), consistent with their higher in-index weights.
Separately from the theme-level view, the data identifies 131 pairs of funds across the full set where portfolios overlap by more than half on a weight basis. The table of largest such pairs shows overlaps as high as 100% (PDBA and EVMT, agriculture) and 85% (IBBQ and IBB, biotech), with fees on these pairs ranging from 0.19% to 0.75% depending on the fund. Holding both funds in a pair of this kind is, by weight, close to holding one of them twice.
One-year total returns varied widely by theme, from +95.8% in semiconductors to −22.8% in blockchain and crypto equities, with the count of funds beating the S&P 500 over one year ranging from 0 of several funds in some themes to all funds in others, such as 9 of 9 in semiconductors and 8 of 8 in biotech.
Readers can check any fund's current in-index weight, active share, fee, and overlap with other named funds on the ETFIQ live desk, where the underlying N-PORT filings and daily price data are refreshed.