The Nasdaq Composite index includes all of the companies traded on the exchange

The Nasdaq 100 index tracks the exchange's 100 largest non-financial companies

This index was created in 1985, over a decade after the Nasdaq first launched. The companies on the index must meet certain criteria, including having a minimum average daily trading value of $5M.

The Nasdaq is typically the world's second-largest stock exchange when measured by the total market value of the companies listed on the exchange.

A stock index is a group of companies clustered together, often providing a condensed snapshot of a market segment.

Visualize the differences between the New York Stock Exchange and the Nasdaq.

The Nasdaq's 'Magnificent 7' have an outsized impact on the Nasdaq 100's performance

These seven companies are Alphabet, Amazon, Apple, Meta, Microsoft, Nvidia, and Tesla. They're often responsible for over 40% of the Nasdaq 100 index's gains, but the exact percentage varies from year to year.

The Nasdaq was founded in 1971, marking the debut of electronic trading

The Nasdaq stock exchange arguably invented electronic trading, making it a key part of fintech history. It's often used as a benchmark for how the tech industry is performing.

Find out how companies decide which stock exchange to list on

Tech companies often prefer to list on the tech-focused Nasdaq, whereas more traditional organizations opt for the New York Stock Exchange. Sometimes the choice is made partly based on the services an exchange offers a company.

The dot-com bubble burst in 2000 when the Nasdaq dropped more than 76% in roughly 2 years

Between 1995 and 2000, the Nasdaq Composite index jumped from roughly 1,000 to 5,000 amid excitement over new internet companies. As venture capitalists dumped money into startups, those same companies struggled to turn a profit, leading to a bubble. The Nasdaq wouldn't reach its former high until 2015.

'The stock market' can be loosely defined as a set of exchanges and other places where shares of public companies are bought and sold.

The fees for keeping a company listed on the NYSE are typically higher than the Nasdaq's.

The stock market, explained in 3 minutes

The stock market consists of a set of exchanges and other venues where shares of public companies are bought and sold. The Nasdaq and the New York Stock Exchange are two of the most well-known exchanges in the US, while major exchanges also operate around the world, including in Tokyo, Shanghai, London, and São Paulo.

Investors rely on the S&P 500 as a benchmark for the state of the economy

Since the index represents a broad range of diverse industries, it's become a proxy for the market itself and a common benchmark for investors to compare returns and performance patterns against. Generally speaking, when someone says a stock is under- or out-performing the market, that actually means under- or out-performing the S&P 500. The S&P 500 is exchange-agnostic, and includes companies listed on both the NYSE and Nasdaq.

Read about when Nasdaq partnered with the London Stock Exchange in 1992, and other key moments in Nasdaq history

The partnership became the first intercontinental linkage between capital markets, setting the stage for worldwide trading amid increasing globalization. Nasdaq separated from its parent company in 2006, becoming a fully independent licensed national securities exchange. A year later, it added the Scandinavian-based Exchange, OMX.

The Dow Jones Industrial Average is a stock market index

The Dow Jones Industrial Average tracks 30 large U.S. companies from all major U.S. sectors except for utilities and transportation. It's considered a bellwether of the U.S. economy.

The S&P 500, managed by the same company, is another major stock index

Also run by S&P Dow Jones Indices, the S&P 500 tracks 500 large US firms using market-value weighting. Many analysts view it as a more accurate gauge of the American economy.

Millions of Americans will be invested in SpaceX because of the fast-tracked process to list SpaceX on the Nasdaq 100, and, subsequently, the index funds that track it.

The Dow now tracks 30 major US companies across various industries

Since 1928, the DJIA has included 30 firms. Today's group spans technology, healthcare, and finance—with Apple, Microsoft, JPMorgan Chase, Pfizer, and Coca-Cola among its most recognized components.

See every company in and out of the Dow since 1928

The index has had 30 companies since 1928. See each company’s tenure on the index and what firms were added or replaced by year and industry.

The S&P 500 is composed of 500 companies, but has more than 500 total listings

Since some large companies have dual-class stock structures (like Alphabet and Fox Corporation), there are multiple listings on the S&P 500 for the same company. S&P Global has banned and then reversed bans on companies with dual-class structures multiple times since first allowing dual-class stocks in 2014.

Dow components are chosen by a committee, not a formula

Unlike many indices, the Dow has no strict rules for inclusion. A small committee at S&P Dow Jones Indices uses judgment—favoring companies with strong reputations, steady growth, and broad investor interest.

The Dow Jones Industrial Average vs. the S&P 500: Which one is a better representation of the economy?

The Dow and S&P 500 are both indexes meant to provide a broad representation of the economy. The Dow has 30 companies and is weighted by share price, while the S&P 500 has 500 different companies weighted by market capitalization. Since the indexes are so different, investors don't always agree on which index is a better representation of the economy—though the two move in the same direction more than 90% of the time.

A 'large-cap' company has a market capitalization of more than $10B

The S&P 500 is primarily composed of large-cap companies. The idea is that the index provides a big-picture view of the economy by assessing the performance of many of the largest public companies across different industries. The median market capitalization of companies listed on the S&P 500 is around $40B.

Before the S&P 500 launched in 1957, Standard and Poor's had a daily index with just 90 companies

Unlike previous indexes from S&P, the S&P 500 could be computed in real time using computer technology that tracked stock tickers across stock exchanges. This innovation is partly what led to 500 companies being listed on the index, a huge increase from the 90 companies in S&P's flagship index when the company had to do all the analysis by hand.

What’s up with the new Texas Stock Exchange?

The two biggest stock exchanges in the U.S. are both based in New York—the New York Stock Exchange and the Nasdaq. But a potential new “Texas Stock Exchange”—which would be based in, you guessed it, Texas—could change that. To find out more about the project, backed by enormous companies such as BlackRock and Citadel, watch this video.

More than 650 companies went public in the US in 1996

As the dot-com bubble reached its peak, most dot-com companies went public with little proof of being profitable and were often overvalued. In 1999, the Nasdaq's price-to-earnings ratio (a tool used to determine a stock's value that divides its price by earnings) hit 90.2, signaling that many companies were operating at a net loss. Startups promised investors that more time and money would help scale their businesses and become profitable.

The S&P 500 selection committee has strict rules around adding a company to the index

While the decision to add a company to the index is ultimately up to the selection committee, any prospective company has to meet some criteria to be considered. To join, the company must have been profitable for the last four quarters, must have a market capitalization exceeding $22.7B, and meet certain requirements around tradeable stock availability (or float).

Companies sometimes change which stock exchange they're listed on.

See a real-time list of the most shorted stocks in the US

Every two weeks, the Nasdaq and New York Stock Exchange release the stocks with the most short positions. Some of the companies with the highest short positions as of early 2026 were Hims & Hers and Groupon.

In late 2025, the top 10 companies in the S&P 500 made up more than 40% of the index's total value

This raised concerns for investors about the index's risk exposure. As many large tech companies continued posting record highs, analysts argued that the top-heavy index was becoming less representative of the economy as a whole.

The Dow’s price-weighted formula makes stock price matter more than size

Unlike most indices, which weigh companies by market value, the DJIA is price-weighted—meaning higher-priced stocks have more influence on its movements. As a result, a company’s share price matters more than its overall size.

The Dow Jones Industrial Average was created in 1896

Charles Dow introduced the DJIA on May 26, 1896, as a simple average of 12 industrial stocks. Although it became the nation’s most enduring market index, none of its original companies remain in the Dow today.

See the top 100 ETFs by trading volume

This list grabs the top 100 by trading volume, or the average number of shares that have traded hands over a 3-month period. Top of the list is a semiconductor-focused fund from Direxion, followed by other tech-centric offerings.

The number of publicly traded companies has decreased in recent years.

In 1996, more than 7,300 companies traded publicly on US stock markets, but that number has recently dropped to 4,300. Economists point to two reasons: First, going public requires full disclosure of operations, exposing it to scrutiny from investors, competitors, and analysts. Second, the IPO process is expensive and time-consuming.

Index funds are typically structured as either mutual funds or exchange-traded funds, but investors can manually recreate an index through 'direct indexing.'

What is after-hours trading?

While both the New York Stock Exchange and the Nasdaq open at 9:30 am ET and close at 4 pm ET, some trading is allowed after that. After-hours trading was once only open to institutional investors and people with particularly high net worths. Now, with the advent of computers, anyone can trade stocks anywhere online, and those regulations have broadened.

Watch how the S&P 500 is actually calculated

After accounting for each company's float-adjusted market capitalization (a metric that combines the price of a company's stock, the total number of shares, and the stock's float, which means how many shares are actually available), the S&P 500 formula uses a divisor to create the index number. However, what the divisor is and what it represents are secrets.

Even iconic companies can get dropped from the Dow

The Dow’s lineup evolves as the economy changes. General Electric, part of the original 1896 index, was removed in 2018, after 122 years. ExxonMobil, once the world’s largest company, was replaced by Salesforce in 2020.

The number of publicly traded companies has decreased significantly

The stock market hit a peak in 1996, when more than 7,000 companies were publicly traded. But in 2024, there were nearly half that many publicly traded companies.