Nasdaq 100 What Is It? A Beginner’s Guide to the Index

Nasdaq 100 what is it? The Nasdaq-100 is a stock market index designed to track 100 of the largest eligible non-financial companies listed on the Nasdaq Stock Market. It includes businesses from several industries, although many people associate it mainly with large technology companies.

An index is a benchmark: it measures how a selected group of securities performs over time. The Nasdaq-100 is not a company, an exchange, or a stock that you can buy directly. This guide explains how the index works, how it differs from other indexes, and what risks its composition may create.

Important: An index’s past performance does not predict future results. Funds and other products that track an index can lose value, and their fees and returns may differ from the index itself. This article is for educational purposes only and is not investment advice.

What Is the Nasdaq-100 Index?

The Nasdaq-100, often identified by the ticker symbol NDX, measures the performance of large domestic and international non-financial companies listed on Nasdaq. Companies must meet eligibility rules, which include requirements related to listing, liquidity, and market capitalization.

The index is designed to represent 100 companies, but the number of securities it contains can temporarily exceed 100. This can happen when a company has multiple eligible share classes or when a qualifying large company is added through Nasdaq’s fast-entry process. Financial companies are excluded. Its constituents span technology, consumer services, health care, industrials, and other sectors, so the Nasdaq-100 is not a technology-only index.

Nasdaq updated the index methodology on May 1, 2026. The objective remains to represent large Nasdaq-listed non-financial companies, while the updated rules refine eligibility, weighting, and the timing of reviews. See the current Nasdaq-100 methodology for the full rules.

How Does the Nasdaq-100 Work?

The Nasdaq-100 uses modified market-capitalization weighting. Market capitalization is a company’s market value, generally calculated from its share price and shares outstanding. In a standard market-cap-weighted index, larger companies have more influence on the index than smaller ones.

The Nasdaq-100 modifies this approach with rules that adjust constituent weights and limit concentration. As a result, the largest companies can still have substantial influence, but the index’s methodology places limits on how much weight they can hold. A large constituent’s price movement may therefore affect the index more than a smaller constituent’s movement.

Nasdaq reconstitutes the index annually and conducts scheduled quarterly reviews and rebalances. Reconstitution reviews which companies belong in the index; rebalancing adjusts constituent weights and, under the updated methodology, may also change membership during specified quarterly reviews. Fast entry may allow certain very large eligible new listings to join between scheduled events. These rules do not prevent losses or ensure that future constituents will perform well.

Nasdaq-100 vs. Nasdaq Composite vs. S&P 500

These indexes are often discussed together, but they represent different groups of companies. The Nasdaq-100 focuses on large non-financial companies listed on Nasdaq. The Nasdaq Composite covers a much broader range of Nasdaq-listed stocks, including financial companies. The S&P 500 tracks 500 leading U.S. companies across industries and exchanges.

The S&P 500 is market-cap weighted, while the Nasdaq-100 uses a modified market-cap approach. Both can be influenced by their largest companies, but their selection rules and sector exposure differ. Read the Nasdaq Composite methodology and the S&P 500 overview for more detail.

What Can Affect the Nasdaq-100?

The index may respond to company earnings, economic data, interest-rate expectations, changes in consumer demand, and shifts in investor sentiment. Because some constituents have much greater weights than others, a handful of large companies can have an outsized effect on its daily performance.

Sector concentration is another consideration. The index includes companies from several industries, but its weighting can leave it more exposed to some sectors than a broader index. A decline in a heavily weighted company or sector may therefore have a noticeable effect. Diversification across multiple constituents does not eliminate market risk.

What Does Diversification Mean for Index Investors?

Warren Buffett made a broader point about owning a range of businesses in his 2013 Berkshire Hathaway shareholder letter: “own a cross-section of businesses that in aggregate are bound to do well.” His discussion specifically refers to an S&P 500 index fund for a trust; it is not an endorsement of the Nasdaq-100, which has different constituents and risks.

Buffett’s letter discusses broad-market investing and specifically refers to the S&P 500. You can read the original shareholder letter.

Can You Invest Directly in the Nasdaq-100?

No. The Nasdaq-100 is an index, not an investment product, so investors cannot buy it directly. Funds and other products may be designed to track the index, but each has its own structure, fees, risks, and tracking differences. An index fund seeks to follow an index; its performance may not match the index exactly.

Before evaluating a product, understand what it tracks, how it is weighted, what it costs, and how it may behave in a declining market. A product linked to the Nasdaq-100 is not the same as owning every company in the index directly. Learn more about how index funds and ETFs work.

Key Takeaways

• The Nasdaq-100 is an index of large eligible non-financial companies listed on the Nasdaq Stock Market.
• It is different from the Nasdaq exchange, the Nasdaq Composite, and the S&P 500.
• Its modified market-cap weighting gives larger companies more influence, subject to the index methodology.
• Nasdaq periodically reviews the index; membership and weights can change.
• Investors cannot buy the index directly, and products that track it carry their own fees and risks.
• Sector and constituent concentration can increase volatility, and losses are possible.

Educational notice: This article is for educational purposes only. It is not investment, tax, or legal advice, and it is not a recommendation to buy or sell any security. Investing involves risk, including the possible loss of principal.