S&P 500 vs. Nasdaq-100 vs. Dow 30
Compare membership, weighting methods, and what each index can and cannot represent.
Read the draftHow Market Watch 360 Calculates
Why We Use IVV, QQQ, and DIA as Weight References
ETF holdings can provide dated portfolio weights, but they are not automatically the official S&P 500, Nasdaq-100, or Dow calculations.
Draft updated · owner review pending
The current desktop app downloads IVV holdings at launch for its S&P 500 stock weights, with a built-in fallback copy if the download fails. The website's separate Nasdaq-100 and Dow illustrations use dated QQQ and DIA references; those two markets are not yet implemented in the Windows app.
A useful reference with a different owner
An ETF owns assets and publishes its own portfolio holdings. The index provider defines its constituent selection, weights, divisor, and corporate-action treatment. A fund may hold cash or use operational adjustments and has expenses. Even when tracking is close, the fund's holdings file and the benchmark's official weight file can differ in timing and values.
Keep the three distinctions visible
IVV is the app's current reference for its S&P 500 basket. QQQ tracks the Nasdaq-100 and DIA tracks the Dow, but their dated holdings appear only in the website's static market artwork today. The Nasdaq-100 uses modified market-cap weighting; the Dow uses prices and a divisor. A percentage of DIA net assets is not the Dow's official price-based constituent influence.
How to label a basket
When summing 30 ETF holdings, name the fund, holdings date, and whether the percentages are rounded. Describe the total as ETF-based estimated coverage. Keep any index close and chart snapshot on its own date. Never attach a fund weight snapshot to a different date's index movement and imply a historical contribution was calculated.
Key takeaway
ETF holdings help explain relative influence when carefully dated and labeled. They are a transparent input to an estimate, not a replacement for the official index rulebook.
Sources and further reading
- iShares Core S&P 500 ETFETF portfolio reference, not the official index calculation
- Invesco QQQ TrustETF portfolio reference, not the official index calculation
- SPDR Dow Jones Industrial Average ETF TrustETF portfolio reference, not the official Dow divisor
- S&P U.S. Indices MethodologyOfficial S&P 500 selection and float-adjusted weighting methodology
- Nasdaq-100 Index MethodologyOfficial modified market-cap weighting and constituent rules
- Dow Jones Averages MethodologyOfficial Dow 30 price-weighting methodology