Dow Jones vs. S&P 500 vs. Nasdaq: What Each Index Measures (Nov. 5, 2026)

Information checked: November 5, 2026, 11:06 p.m. Toronto time — Eastern Standard Time (EST, UTC−05:00; November 6, 2026, 04:06 UTC).

The Dow Jones Industrial Average, S&P 500, and Nasdaq Composite all track U.S.-listed equities, but they measure different slices of that market and assign different influence to each stock. The Dow follows 30 large U.S. companies using share-price weighting; the S&P 500 represents 500 large companies using float-adjusted market-cap weighting; and the Nasdaq Composite covers eligible common-type stocks listed on the Nasdaq Stock Market, also weighted by market capitalization.

For Canadian readers, the key is to treat these as U.S. benchmarks, not interchangeable readings of “the market” and not measures of Canada’s stock market. The S&P/TSX Composite is the broad headline benchmark for Canadian equities. Comparing the index rules—and, when relevant, currency effects—helps explain why the three U.S. indexes can move differently on the same day.

Destaques

• The Dow’s price weighting gives a higher-priced share more influence, even if its company is not the largest by market value.
• The S&P 500 is a broad large-cap U.S. benchmark; it includes 500 companies and covers about 80% of available U.S. market capitalization.
• “Nasdaq” can mean the Nasdaq Composite or the narrower Nasdaq-100, so check the full index name.
• Canadian investors comparing fund returns should account for the fund’s benchmark, fees, tracking difference, and any U.S.-dollar exposure.

What does a stock market index measure?

An index is a rules-based calculation that summarizes the performance of a selected group of securities. Its level is not a share price, and the number of index points is not a dollar amount that an investor can buy. What matters in a comparison is usually the percentage change over the same period, the securities included, and how the index weights them.

Two common weighting methods explain much of the difference. A price-weighted index gives greater weight to stocks with higher share prices. A market-cap-weighted index gives greater weight to companies with higher market values, generally calculated from share price multiplied by shares outstanding. Float-adjusted market-cap indexes count only shares considered available for public investment. These methods can produce different results even when the indexes hold some of the same companies.

How is the Dow Jones Industrial Average constructed?

“The Dow” usually means the Dow Jones Industrial Average, or DJIA. S&P Dow Jones Indices describes it as a price-weighted measure of 30 U.S. blue-chip companies. Its companies come from a range of industries, with transportation and utilities excluded because those sectors have separate Dow averages. The constituents are selected by a committee rather than by applying a simple ranking of the 30 largest U.S. companies.

Price weighting has a practical consequence: a stock with a higher dollar share price has more influence on the Dow than a lower-priced stock, even if the lower-priced company is worth more overall. Stock splits would otherwise change a component’s price without changing the company’s value, so the Dow’s divisor is adjusted to keep the index calculation continuous. The official DJIA overview and Dow Jones Averages methodology describe the construction.

What does the S&P 500 represent?

The S&P 500 tracks the large-cap segment of the U.S. equity market. Its 500 constituent companies span leading industries, and the index covers approximately 80% of available U.S. market capitalization, according to S&P Dow Jones Indices. It is broad, but it is not a list of every U.S. public company: smaller companies and stocks that do not meet the index’s eligibility rules are outside its scope.

The S&P 500 is float-adjusted market-cap weighted. In plain language, a company’s weight depends on its market value and the portion of its shares available to public investors. As a result, the largest constituents can account for a significant share of the index’s movement. A gain or loss among those companies may matter more to the index than the same percentage move in a smaller constituent. See the official S&P 500 overview and S&P U.S. Indices methodology.

Does “Nasdaq” mean the Nasdaq Composite or Nasdaq-100?

Nasdaq is a stock exchange operator as well as the name used in several index titles. In market coverage, “the Nasdaq” often means the Nasdaq Composite, but sometimes people mean the Nasdaq-100. They are different indexes.

The Nasdaq Composite includes eligible domestic and international common-type stocks listed on the Nasdaq Stock Market. Nasdaq’s methodology says it has no industry, country, or market-cap eligibility screen beyond its security and listing rules, and that it is market-cap weighted. It is therefore not a technology-only index, although technology companies and other growth-oriented businesses have a visible influence on its performance.

The Nasdaq-100 is narrower: it includes 100 of the largest domestic and international non-financial companies listed on Nasdaq, selected by market capitalization. Financial companies are excluded. Before comparing an index chart or a fund, check whether its benchmark is the Composite or the Nasdaq-100. Nasdaq publishes the Nasdaq Composite overview, its Composite methodology, and the Nasdaq-100 description.

How do the Dow, S&P 500, and Nasdaq compare?

This comparison describes index design, not a forecast or recommendation. The indexes’ numerical levels cannot be compared directly: each has its own calculation base and divisor. Compare percentage returns over matching dates and confirm whether the figures are price returns or total returns. A total-return version includes reinvested dividends, while a price-return figure does not.

Why can the indexes move in different directions?

Their constituent lists and weighting rules differ. A price change in a high-priced Dow stock can influence the Dow more than the same percentage move in a lower-priced component. In the S&P 500 and Nasdaq Composite, the market value of a company is more important to its weight, so the largest constituents can dominate more of the daily result. The Nasdaq Composite’s listing-based universe also differs from the S&P 500’s large-cap selection process.

That means a headline such as “stocks rose today” can conceal a mixed session. One index may rise because a few large companies gained while another is flat or lower. To understand the breadth of a move, readers can check the index’s sector exposure, biggest weights, number of advancing and declining stocks, and whether the report uses a price-return or total-return version. Those details provide context beyond the headline index point change.

What should Canadian investors keep in mind?

The S&P/TSX Composite is the headline and broadest index in the S&P/TSX family, and is designed to measure Canadian equities. The Dow, S&P 500, and Nasdaq indexes instead measure U.S.-listed securities. A Canadian portfolio can use both types of benchmarks for comparison, but they answer different questions: U.S. large-company performance is not the same as Canadian market performance.

An index itself cannot be purchased directly. Mutual funds and exchange-traded funds may track an index, but their returns can differ because of fees, trading costs, sampling, and tracking error. For a Canadian investor, a U.S.-listed fund can also gain or lose value in Canadian dollars as the CAD/USD exchange rate changes; currency hedging may alter that exposure. Check the fund’s facts or prospectus for its actual benchmark, listing currency, currency-hedging approach, costs, and risks. The Ontario Securities Commission’s investor resource on foreign-listed ETFs explains the currency effect, while the U.S. SEC’s index fund guide notes that investors cannot invest directly in an index and that fees and tracking error can affect fund returns.

Frequently asked questions

Is the Nasdaq Composite the same as the Nasdaq-100?

No. The Composite includes eligible Nasdaq-listed common-type stocks across sectors; the Nasdaq-100 covers 100 of the largest Nasdaq-listed non-financial companies.

Which index is the broadest measure of U.S. stocks?

Of these three, the Nasdaq Composite includes the broadest Nasdaq-listed universe. The S&P 500 is a broad large-cap U.S. benchmark, while the Dow covers 30 selected companies. None represents every U.S. stock.

Which index should Canadians use to track Canada’s stock market?

The S&P/TSX Composite is the headline broad-market index for Canadian equities. The Dow, S&P 500, and Nasdaq indexes track U.S.-listed stocks.