How much of a theme is already the index
By their latest holdings filings, the typical thematic ETF has 32% of its weight in stocks the S&P 500 already holds, and 55 of 244 funds are more than sixty percent index names.
Across 27 themes and 285 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%.
94 pairs of funds hold portfolios that are more than half identical by weight; holding both is close to holding one of them twice.
A thematic ETF is sold as a way to own a specific idea, but the holdings often say something else. Across 244 funds, the typical thematic ETF holds 32% of its weight in stocks already inside the S&P 500. That is not a small overlap. For 55 of those funds, more than sixty percent of the portfolio by weight is names the S&P 500 already owns. The theme, in those cases, is layered on top of a large amount of index exposure that an investor may already hold elsewhere.
The degree of overlap varies sharply by theme. Semiconductors, as a group, has a median 81% of weight already in the S&P 500 and a median active share of 82%, alongside a beat rate of 9 of 9 funds against the S&P 500 over one year and a median total return of +95.7%. Digital infrastructure and data centers shows 64% in the S&P 500. At the other end, electric vehicles and batteries sits at 9%, cannabis at 0%, and space at 14%, meaning these themes hold very little that the S&P 500 already contains. Clean energy, at 10%, and nuclear and uranium, at 15%, are similarly distinct from the index by this measure.
Fees do not move in step with how distinct a fund is. Across 27 themes and 285 funds, the median fee is 0.60%. When the fee is measured only against the part of each portfolio that differs from the S&P 500, the median is also 0.60%. Semiconductors charges a median 0.30% fee but 0.40% for the differentiated portion, since so much of the fund's weight is already index exposure. Nuclear and uranium charges 0.70% both ways, reflecting a portfolio that is almost entirely distinct from the S&P 500 (100% active share). Space carries a median fee of 0.80%, also unchanged when measured against just its distinct holdings.
Overlap between individual funds tracking similar themes is also common. Ninety-four 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 closest pairs sit in semiconductors: SOXQ and SOXX overlap by 83%, at fees of 0.19% and 0.33%, and SHOC and SMH overlap by 82%, at 0.40% and 0.35%. Cybersecurity pairs SPAM and PSWD overlap by 76%, and blockchain and crypto equities pairs BKCH and DAPP overlap by 72%. Fee levels within these overlapping pairs differ, sometimes by more than double, for portfolios that share most of their weight.
Return figures in the table are one-year totals and vary widely across themes, from +95.7% in semiconductors to −18.8% in gaming, esports and betting, and beat rates against the S&P 500 range from 9 of 9 funds down to 0 of several. These are single-year figures and reflect the period measured, not a permanent ranking of themes.
On the live desk, a reader can look up any individual fund's in-index weight, active share, and fee for the differentiated portion, along with the current overlap percentage against other funds in the same theme.
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 | 9 | 81% | 82% | 0.30% | 0.40% | 9 of 9 | +95.7% |
| Defense | 19 | 35% | 98% | 0.50% | 0.50% | 0 of 11 | +6.2% |
| Artificial intelligence | 47 | 60% | 81% | 0.70% | 0.80% | 21 of 26 | +30.4% |
| Electrification and the grid | 14 | 27% | 99% | 0.60% | 0.60% | 8 of 11 | +58.2% |
| Cybersecurity | 7 | 33% | 99% | 0.50% | 0.50% | 7 of 7 | +26.2% |
| Infrastructure | 9 | 33% | 97% | 0.50% | 0.50% | 0 of 7 | +14.7% |
| Cloud and software | 8 | 45% | 92% | 0.40% | 0.40% | 2 of 7 | +9.6% |
| Nuclear and uranium | 9 | 15% | 100% | 0.70% | 0.70% | 0 of 8 | +4.2% |
| Broad innovation and megatrends | 31 | 51% | 86% | 0.50% | 0.60% | 14 of 29 | +17.5% |
| Internet and e-commerce | 14 | 29% | 95% | 0.70% | 0.70% | 0 of 14 | −14.4% |
| Robotics and automation | 12 | 17% | 94% | 0.70% | 0.70% | 5 of 8 | +21.2% |
| Clean energy | 17 | 10% | 99% | 0.60% | 0.60% | 10 of 15 | +22.8% |
| Quantum computing | 3 | 36% | 84% | 0.50% | 0.50% | 1 of 1 | +50.8% |
| Water | 7 | 38% | 100% | 0.60% | 0.60% | 0 of 6 | −3.5% |
| Space | 8 | 14% | 99% | 0.80% | 0.80% | 2 of 2 | +25.5% |
| Digital infrastructure and data centers | 8 | 64% | 94% | 0.50% | 0.50% | 5 of 7 | +32.3% |
| Blockchain and crypto equities | 12 | 18% | 98% | 0.60% | 0.60% | 1 of 12 | +2.1% |
| Electric vehicles and batteries | 13 | 9% | 98% | 0.50% | 0.50% | 7 of 11 | +37.6% |
| Genomics and biotech innovation | 4 | 18% | 98% | 0.50% | 0.50% | 3 of 4 | +71.1% |
| Cannabis | 4 | 0% | 100% | 0.80% | 0.80% | 0 of 4 | +1.1% |
| Food and agriculture | 6 | 36% | 100% | 0.60% | 0.50% | 5 of 5 | +23.1% |
| Fintech and digital payments | 4 | 42% | 94% | 0.70% | 0.80% | 0 of 4 | −16.4% |
| Gaming, esports and betting | 7 | 16% | 100% | 0.60% | 0.60% | 0 of 7 | −18.8% |
| Metaverse and immersive tech | 4 | 46% | 78% | 0.60% | 0.80% | 1 of 4 | +11.4% |
| Healthcare innovation and GLP-1 | 5 | 27% | 99% | 0.50% | 0.60% | 3 of 5 | +22.9% |
| Longevity and aging | 1 | 45% | 95% | 0.50% | 0.50% | 0 of 1 | +10.4% |
| Pets and consumer themes | 3 | 18% | 99% | 0.50% | 0.50% | 0 of 2 | −16.1% |
Same portfolio, two names: pairs more than half identical
| Pair | Weight overlap | Theme | Fee, first | Fee, second |
|---|---|---|---|---|
| SOXQ and SOXX | 83% | Semiconductors | 0.19% | 0.33% |
| SHOC and SMH | 82% | Semiconductors | 0.40% | 0.35% |
| FTXL and SOXQ | 78% | Semiconductors | 0.60% | 0.19% |
| SPAM and PSWD | 76% | Cybersecurity | 0.35% | 0.20% |
| SMH and SOXX | 74% | Semiconductors | 0.35% | 0.33% |
| BUG and WCBR | 74% | Cybersecurity | 0.50% | 0.45% |
| BKCH and DAPP | 72% | Blockchain and crypto equities | 0.50% | 0.52% |
| WGMI and MNRS | 71% | Blockchain and crypto equities | 0.75% | 0.59% |
| WEED and UX | 71% | Cannabis | 0.41% | 0.77% |
| WDEF and XDEF | 71% | Defense | 0.45% | 0.35% |
| BITQ and DAPP | 71% | Blockchain and crypto equities | · | 0.52% |
| BITQ and BKCH | 71% | Blockchain and crypto equities | · | 0.50% |
| SHOC and SOXX | 70% | Semiconductors | 0.40% | 0.33% |
| HERO and NERD | 70% | Gaming, esports and betting | 0.50% | 0.50% |
| FIW and PHO | 70% | Water | 0.50% | 0.59% |
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 10, 2026. https://etfiq.com/research/2026-09-10/themes-index Free to use with attribution; the underlying file is at https://etfiq.com/data/thematic.json.