S&P 500 vs. Nasdaq vs. Dow Jones: What's the Difference?

By USWealth Editorial Team·September 23, 2026·2 min read

The three major US indexes are quoted on every news broadcast, but they measure the market in very different ways. Here's what each one really tells you.

When you hear that "the market was up today," the speaker usually means one of three indexes: the S&P 500, the Nasdaq Composite or the Dow Jones Industrial Average. Each is built differently, which is why they can move in different directions on the same day.

The S&P 500

The S&P 500 tracks roughly 500 of the largest US public companies, chosen by a committee at S&P Dow Jones Indices. It is market-capitalization weighted, meaning bigger companies have a larger influence. Because it covers about 80% of the total value of US stocks, professionals treat it as the best single gauge of the US market. You can read the official methodology at S&P Dow Jones Indices.

The Nasdaq Composite

The Nasdaq Composite includes nearly all stocks listed on the Nasdaq exchange — several thousand companies. It is also market-cap weighted and heavily tilted toward technology and growth companies. As a result, it tends to rise faster in bull markets and fall harder in sell-offs. Its cousin, the Nasdaq-100, includes the 100 largest non-financial Nasdaq companies and is tracked by popular ETFs.

The Dow Jones Industrial Average

The Dow, created in 1896, contains just 30 large "blue-chip" companies. Unusually, it is price-weighted: a stock with a higher share price has more influence regardless of the company's actual size. That makes the Dow a less precise market gauge, but its long history keeps it in the headlines.

Which Index Should You Follow?

Broadest view of large US companies: S&P 500
Technology and growth exposure: Nasdaq
A historical snapshot of blue chips: Dow

For investing, many people buy funds that track these indexes. Our index fund investing guide explains how, and our market capitalization explainer shows why weighting matters.

Frequently Asked Questions

Which index is the best measure of the US stock market?

Most professionals use the S&P 500 because it covers a large share of US market value and uses market-cap weighting. Total market indexes are even broader.

Why does the Dow move by hundreds of points?

Because the Dow is price-weighted and quoted in points, its moves look large in absolute terms. Percentage changes are a better way to compare it with other indexes.

Can I invest directly in an index?

No, but you can buy an index fund or ETF that tracks it closely at very low cost.

Note: This article is for educational purposes only and is not investment advice. See our Disclaimer.