Thematic ETFs are often sold as a way to target a specific idea, from semiconductors to space to gene editing. The data behind those labels tells a more mixed story. Across 392 funds, the typical thematic ETF holds 32% of its weight in stocks already found in the S&P 500. Put another way, the median fund's active share, the portion of its portfolio that differs from the index, is well below total. 73 of the 392 funds are more than sixty percent index names by weight, meaning the "theme" sits on top of a large base of familiar large-cap holdings.
This varies a great deal by theme. Energy security and critical technology funds show a median 85% of weight already in the S&P 500, and AI infrastructure and chips and Semiconductors both show 65%. At the other end, Cannabis funds show 0% in the index, and Silver miners and Gold miners show 2% and 6%. Active share follows the same pattern in reverse: Gold miners, Nuclear and uranium, Space, Rare earth and critical materials, Lithium and battery metals and several others show 100% active share, while Metavered and immersive tech, Artificial intelligence and Quantum computing sit lower, in the 80s.
Fees do not track this distinction closely. Across 419 funds in 54 themes, the median fee is 0.60%, and when the fee is measured only against the part of each fund that differs from the S&P 500, the median fee for that difference is also 0.60%. Theme by theme, the two numbers are close in most rows, for example Infrastructure at 0.60% and 0.60%, or Robotics and automation at 0.80% and 0.80%. A few themes show a small gap, such as Artificial intelligence at 0.70% against 0.80%, or Cannabis at 0.80% against 0.60%.
A separate pattern shows up between funds rather than within them. 128 pairs of funds hold portfolios that are more than half identical by weight, meaning that holding both is close to holding one of them twice. The listed examples include GII and IGF in Infrastructure at 97% weight overlap, IBB and IBBQ in Biotech at 86%, and several semiconductor pairs, including SOXQ and SOXX at 83% and FTXL and SOXX at 78%. Fees on these overlapping pairs differ in some cases, as with IBB at 0.44% against IBBQ at 0.19%, and SOXQ at 0.19% against SOXX at 0.33%.
One-year total returns, where reported, ranged widely across themes, from Semiconductors at +78.5% and Genomics and gene editing at +62.8% to Blockchain and crypto equities at −37.4% and Nuclear and uranium at −34.3%. These numbers sit alongside the in-index and active share numbers in the same table, so a reader can see return, index overlap and fee side by side for each theme.
Readers can look up any individual fund's in-index percentage, active share, fee, and overlap with other funds in the same theme on ETFIQ's fund pages.