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

See a timeline of S&P Global's history—the company behind the S&P 500

From the 1941 merger of Standard Statistics and Poor's Publishing to the creation of the S&P 500 in 1957, the company that created the famous index has long been a leader in financial intelligence.

S&P Global, the company that makes the S&P 500, is listed on the S&P 500

When the S&P 500 index was released in 1957, it was helpful for investors, but not necessarily profitable. S&P Global now makes more than $1B a year just from selling its index data. Alongside its other services, like credit ratings, S&P Global makes more than $14B a year.

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.

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.

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).

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.

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.

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.

Some argue that the S&P 500 is actually an actively managed index

Some critics of the S&P 500's selection process argue that human involvement makes it an actively managed index. S&P Global maintains that while a human selects the stocks in the index, those decisions are not made with the intent of maximizing performance, but rather, to provide a snapshot of the largest companies across different industries.

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.

Read about the evolution of the S&P 500 and its recession recovery

Since the S&P 500 is considered a bellwether index (meaning it represents the health of the US economy), its value is important for investors in both bull and bear markets. The S&P 500 has been impacted by recessions and downturns, from the 1970s oil crisis to the dot-com crash of the early 2000s.

Visualizing decades of stock market performance

Stock markets and the indexes that track their biggest companies tend to ebb and flow, with long growth periods punctuated by shorter recessions. Track the 60-year history of one of the most common stock market indexes, the S&P 500, with this data visualization. The chart highlights the long-term durability of markets despite appearance of short-term volatility.

The S&P 500 yields a roughly 10.5% average annual return

Tthe factors that go into that calculation are multifaceted—from how inflation impacts it to the stocks themselves. During periods of high inflation, stock performance can be stunted by investor concerns, for instance. The average return also varies based on whether dividends are included.

Read how Vanguard's founder used the S&P 500 to revolutionize retail investing

John Bogle, the founder of The Vanguard Group, created a fund that tracked the S&P 500 in 1976. That fund created an unprecedented opportunity for individual retail investors, brought down fees across the board, and popularized the belief that passive, low-cost index fund investments would outperform actively managed portfolios long-term.

The SPDR S&P 500 ETF is one of the most highly traded funds on the market

State Street, a popular ETF issuer, is responsible for the SPDR S&P 500 ETF. This fund trades under the SPY ticker, and State Street maintains a web page with key facts and figures on SPY. For instance, its expense ratio is 0.0945%, or $9.45 on an initial $10K investment.

How the S&P 500 performed in the first 100 days of each modern US presidential term

The S&P 500 was up 5.3% during President Donald Trump's first 100 days in office during his first term as president, and down 7.1% during the first 100 days of his second term.

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.

Read about the 'gatekeeper' of the stock market, former index chair at S&P Global

David Blitzer, the former index chair at S&P Global, earned the nickname "gatekeeper" of the stock market after helping decide which companies made it into the S&P 500 for 24 years. Blitzer became a legend in the world of indexing and has a reputation for being even-tempered and always wearing a bow tie.

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 stock market's volatility between 2017 and 2025, visualized

The CBOE Volatility Index measures expected stock market volatility using the prices of options on the S&P 500. When traders expect large moves in the market, options prices tend to rise as more options are purchased to bet on the direction of the move.

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.

The Nasdaq's 'Magnificent 7' companies are responsible for roughly 40% of the Nasdaq 100 index's gains, while the remaining 93 companies account for the other 60%.

Dozens of S&P 500 stocks, including Coca-Cola and Walmart—known as the dividend aristocrats—have increased dividends every year for 25 years

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

The 'big bang' of the dot-com era: Netscape's stock price doubled on the day of its initial public offering

The company behind the browser that revolutionized search went public on August 9, 1995. Just before the IPO, the company increased its initial opening price from $14 to $28. On the day the company went public, shares traded as high as $71 before closing at $58.25. The company's market capitalization exceeded $2B. The eye-popping IPO is largely considered the beginning of the dot-com bubble.

As technology evolved, so did Wall Street

Before the telephone was invented in the mid 1800s, people had to trade stocks in person. But once office telephones and computers became commonplace, banks and other financial institutions didn't necessarily need to have their headquarters near exchanges like Wall Street's New York Stock Exchange.

Microsoft Excel is used by over a billion people worldwide

The upstart computer software company Microsoft launched its columns-and-rows spreadsheet program in 1985, enabling users to sort information, create charts, and perform calculations with minimal friction. It would be coupled with Microsoft Word and PowerPoint in 1990 as part of the Microsoft Office for Windows.

CES debuted in 1967 amid a wave of miniaturization in at-home electronics

The rapid development of integrated circuits—the basis of computing power—in the 1960s catalyzed an industrial shift toward miniature devices, including pocket transistor radios, smaller TVs, and more. This first consumer electronics trade show (with a slate of 117 exhibitors and 17,000 attendees) sought to make everyday electronics accessible and portable. See a timeline of early consumer tech with photos.

SpaceX's S-1 or 'prospectus' revealed many previously unknown details about the company, including its unprofitability despite doing $18.7B in revenue in 2025, exactly how many voting shares Elon Musk will have in the company (roughly 85%), and more.

An initial public offering or 'IPO' is the process of a private company becoming public by putting shares of the company on the stock market for purchase.

A century of Billboard issues documenting the evolution of popular music.

Sears sold DIY house kits starting at $600 in its famous catalog from 1908 through the 1940s, resulting in roughly 10,000 'Sears and Roebuck houses' being built.

The name 'Silicon Valley' arose from the founding of Shockley Semiconductor Laboratory in Fairchild Semiconductor in 1956-57, founded near Stanford University in Palo Alto

In 2025, four executives from large tech companies were given positions in the US Army Reserves—including Palantir Chief Technology Officer Shyam Sankar, which reinforced Palantir's ties with the US military and its role as a leading defense partner.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

The power and influence of the American presidency have expanded significantly over time—far beyond what the founders envisioned.

Long before Major League Baseball began allowing instant replay for balls and strikes, an umpire reluctantly used the technology to determine whether a hit was a home run, a move that inadvertently ushered in a new era for the sport.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

Warren Buffett's former professor Benjamin Graham is known as the 'father of value investing,' a strategy in which investors seek to buy stocks trading below their intrinsic worth.

Explore fun facts from the USPS, including unique post office buildings, a stamp that traveled past Pluto, and more.

Meet the 56 signers of the Declaration of Independence—most of whom didn't put pen to paper until August 2, 1776—and see their original signatures.

The American Society of Civil Engineers' infrastructure report card gave the US a C in 2025, its highest grade since the project launched in 1998.

Search a massive database of over 4 decades of clues from the TV quiz show 'Jeopardy!'

'Shogun,' a 1980s TV series, helped popularize sushi in the US by stimulating an American interest in Japanese culture.

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

The first steps to rebuilding your credit score include getting to know exactly what's on your credit report and figuring out how far you are from the '700 club,' or 'good score' range.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Scientists testing how climate change affects plants found, in a years-long simulation study, that poison ivy grew 70% faster with the resulting extra carbon dioxide.

Telehealth demand for GLP-1s for weight loss is booming as consumers seek easier access.

The most expensive ad of all time was for Chanel No. 5 perfume and cost roughly $33M to produce in 2004—about $57M in today's dollars.