How much of a theme is already the index
By their latest holdings filings, the typical thematic ETF has 30% of its weight in stocks the S&P 500 already holds, and 70 of 349 funds are more than sixty percent index names.
Across 37 themes and 413 funds, the median fee is 0.60%; measured against only the part of each fund that differs from the S&P 500, the median fee for the difference is 0.60%.
115 pairs of funds hold portfolios that are more than half identical by weight; holding both is close to holding one of them twice.
A theme fund promises exposure that the S&P 500 does not already give an investor. The data, as of 2026-09-11, shows how much of that promise is delivered. Across 245 funds, the typical thematic ETF holds 32% of its weight in stocks the S&P 500 already owns. That means, on a median basis, roughly a third of a theme fund's portfolio duplicates the broad index most retail and adviser portfolios already hold somewhere. The overlap is not evenly spread: 56 of the 245 funds are more than sixty percent index names, meaning more than half their book is standard S&P 500 constituents dressed in a theme's marketing.
The theme-by-theme table shows how wide the range is. Semiconductors funds carry a median 74% of weight already in the S&P 500, alongside a median active share of 82%, and all nine funds in that group beat the S&P 500 over one year, with a median total return of +98.0%. Digital infrastructure and data centers sits at 64% in-index. At the other end, electric vehicles and batteries shows 9% in-index weight, cannabis shows 0%, and clean energy shows 10%, all with active share at or near 100%. Active share and in-index weight move in the direction you would expect: themes with less overlap into the S&P 500 tend to carry active share close to 100%.
Fees do not track this distinction cleanly. Across 27 themes and 283 funds, 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%. Semiconductors funds charge a median 0.30% fee outright and 0.40% on the differentiated portion; nuclear and uranium funds charge 0.70% on both measures despite 100% active share. Fee level and degree of overlap do not appear to move together in this data.
A separate question is duplication between theme funds themselves. Across the fund universe, 87 pairs hold portfolios more than half identical by weight, meaning that holding both funds in a pair is close to holding one of them twice. The table lists 15 such pairs with overlaps from 68% to 79%. Three semiconductor pairs appear at the top: SHOC and SMH at 79%, FTXL and SOXQ at 77%, and SOXQ and SOXX at 73%. Fees within these pairs vary, for instance FTXL and SOXQ show fees of 0.60% and 0.19% despite 77% weight overlap, and WEED and UX show fees of 0.41% and 0.77% at 71% overlap.
Readers who want to check where a specific fund sits can look up its in-index weight, active share, and fee figures, and cross-reference the pairs table for any holding that overlaps heavily with something else already in a portfolio, on the live ETFIQ desk.
By theme, largest assets first
| Theme | Funds | Median in the S&P 500 | Median active share | Median fee | Median fee for the difference | Beat the S&P 500, one year | Median total return, one year |
|---|---|---|---|---|---|---|---|
| Semiconductors | 11 | 67% | 84% | 0.30% | 0.40% | 9 of 9 | +98.0% |
| Miners and metals | 30 | 7% | 100% | · | · | 21 of 26 | +40.1% |
| Defense | 22 | 37% | 98% | 0.50% | 0.50% | 0 of 12 | +6.7% |
| Artificial intelligence | 50 | 61% | 83% | 0.70% | 0.80% | 20 of 26 | +30.9% |
| Memory and storage | 5 | 20% | 97% | · | · | 0 of 0 | · |
| Electrification and the grid | 17 | 36% | 98% | 0.60% | 0.60% | 9 of 13 | +31.3% |
| Cybersecurity | 7 | 28% | 99% | 0.50% | 0.50% | 5 of 7 | +24.9% |
| Infrastructure | 10 | 32% | 97% | 0.50% | 0.50% | 0 of 7 | +13.5% |
| Cloud and software | 8 | 45% | 92% | 0.40% | 0.40% | 1 of 7 | +7.5% |
| Nuclear and uranium | 10 | 16% | 100% | 0.70% | 0.70% | 0 of 8 | +1.9% |
| Broad innovation and megatrends | 32 | 50% | 86% | 0.50% | 0.60% | 14 of 29 | +17.6% |
| Internet and e-commerce | 14 | 29% | 95% | 0.70% | 0.70% | 0 of 14 | −13.7% |
| Reshoring and manufacturing | 10 | 37% | 97% | · | · | 6 of 8 | +25.6% |
| Robotics and automation | 12 | 19% | 94% | 0.70% | 0.70% | 4 of 7 | +20.6% |
| Clean energy | 18 | 9% | 99% | 0.60% | 0.60% | 10 of 16 | +22.7% |
| Quantum computing | 4 | 35% | 84% | 0.50% | 0.50% | 1 of 1 | +50.4% |
| Water | 7 | 46% | 100% | 0.50% | 0.60% | 0 of 6 | −4.9% |
| Biotech and genomics | 12 | 24% | 99% | 0.50% | 0.50% | 9 of 10 | +46.8% |
| Space | 10 | 9% | 100% | 0.80% | 0.80% | 2 of 2 | +24.5% |
| Digital infrastructure and data centers | 10 | 62% | 88% | 0.50% | 0.60% | 7 of 9 | +34.5% |
| Blockchain and crypto equities | 13 | 19% | 98% | 0.60% | 0.60% | 1 of 12 | +3.1% |
| Therapeutics and medical devices | 9 | 21% | 98% | · | · | 3 of 6 | +22.9% |
| Electric vehicles and batteries | 15 | 9% | 98% | 0.50% | 0.50% | 8 of 12 | +31.7% |
| Cannabis | 5 | 0% | 100% | 0.80% | 0.80% | 0 of 5 | +2.3% |
| Fintech and digital payments | 7 | 41% | 98% | 0.70% | 0.80% | 0 of 5 | −15.9% |
| Food and agriculture | 7 | 35% | 100% | 0.50% | 0.50% | 4 of 6 | +19.2% |
| Shipping, aviation and logistics | 6 | 24% | 99% | · | · | 3 of 4 | +34.7% |
| Energy security and critical technology | 5 | 86% | 95% | · | · | 1 of 3 | +13.8% |
| Energy transition and decarbonisation | 9 | 42% | 98% | · | · | 5 of 8 | +24.9% |
| Gaming, esports and betting | 8 | 17% | 100% | 0.60% | 0.60% | 0 of 7 | −17.9% |
| Metaverse and immersive tech | 4 | 46% | 78% | 0.60% | 0.80% | 2 of 4 | +12.3% |
| Stablecoins and tokenisation | 6 | 25% | 98% | 0.30% | 0.40% | 1 of 2 | +17.1% |
| Photonics and optics | 3 | 34% | 100% | · | · | 0 of 0 | · |
| Healthcare innovation and GLP-1 | 8 | 30% | 98% | 0.50% | 0.60% | 5 of 8 | +21.2% |
| Longevity and aging | 2 | 47% | 95% | 0.50% | 0.50% | 0 of 1 | +9.1% |
| Pets and consumer themes | 4 | 18% | 99% | 0.40% | 0.40% | 0 of 2 | −17.2% |
| Streaming and live entertainment | 3 | 16% | 99% | · | · | 0 of 2 | −20.6% |
Same portfolio, two names: pairs more than half identical
| Pair | Weight overlap | Theme | Fee, first | Fee, second |
|---|---|---|---|---|
| SOXQ and SOXX | 86% | Semiconductors | 0.19% | 0.33% |
| AUAU and GDX | 84% | Miners and metals | · | · |
| ORBX and MARS | 82% | Space | 0.50% | · |
| MARS and WARP | 80% | Space | · | 0.50% |
| SMH and SHOC | 79% | Semiconductors | 0.35% | 0.40% |
| SOXQ and SMH | 77% | Semiconductors | 0.19% | 0.35% |
| SOXQ and SHOC | 77% | Semiconductors | 0.19% | 0.40% |
| GDX and GDMN | 77% | Miners and metals | · | · |
| SPAM and PSWD | 76% | Cybersecurity | 0.35% | 0.20% |
| AUAU and GDMN | 76% | Miners and metals | · | · |
| FIW and PHO | 75% | Water | 0.50% | 0.59% |
| BUG and WCBR | 74% | Cybersecurity | 0.50% | 0.45% |
| XA and WCBR | 73% | Artificial intelligence | · | 0.45% |
| SMH and SOXX | 73% | Semiconductors | 0.35% | 0.33% |
| WEED and UX | 71% | Cannabis | 0.41% | 0.77% |
Method. Holdings from each fund’s latest public SEC N-PORT filing (issuer daily files for ARK and First Trust); in-index weight and active share computed by ETFIQ against the IVV and QQQM books; fees from prospectus XBRL; returns from Tiingo end-of-day prices with distributions reinvested. Themes are ETFIQ’s editorial taxonomy. Medians across funds. Data file: https://etfiq.com/data/thematic.json. Rebuilt every trading night. ETFIQ is an independent publisher and makes no recommendations. Standards
Cite this page. ETFIQ Research, How much of a theme is already the index, data as of Sep 11, 2026. https://etfiq.com/research/2026-09-12/themes-index Free to use with attribution; the underlying file is at https://etfiq.com/data/thematic.json.