Trading the S&P 500

What is the S&P 500 Index?

The S&P 500 Index tracks the performance of 500 of the largest publicly-traded companies in the United States. It’s widely considered to be the best overall measure of the U.S. stock market and economy as a whole.

The index’s history goes back to 1923, when the Standard Statistics Company created its first stock index tracking 233 U.S. companies. In 1941, the company merged with Poor’s Publishing and became known as Standard & Poor’s (S&P). In 1957, the index was expanded to include 500 large-cap stocks, creating the first iteration of the S&P 500.

Today, the S&P 500 is maintained by S&P Dow Jones Indices and is part of the S&P Global 1200 family of indices, which includes:

• S&P MidCap 400, representing mid-cap companies
• S&P SmallCap 600, representing small-cap companies.

Together, the three indices form the S&P Composite 1500, which covers about 90% of the total U.S. market capitalization.

Note: Even though it’s called the S&P 500, the index actually includes 503 stocks since three companies – Alphabet, Fox Corporation, and News Corp – have two share classes listed.

Components of the S&P 500

Current S&P 500 companies

The S&P 500 is the most diversified of the major U.S. stock market indexes. It is made up of 500 companies from 11 different sectors of the economy and has strict entry criteria.

The S&P 500 is weighted by market capitalization, which means the largest companies in the index have a greater influence on its performance than the smallest. As a result, although the index is highly diversified, the technology sector alone has a weighting of 38.8% because it includes three of the world’s four largest companies: Nvidia, Apple, and Microsoft, which have a combined value of $13.7 trillion.

Data source: Vanguard. Sector weightings are accurate as of June 30, 2026.

Largest companies by market cap

The table below shows the 15 largest companies in the S&P as of 2026, organized by weighting.

Source: SlickCharts (weight subject to change)

Changes in constituents

The S&P Dow Jones Indices Committee regularly reviews the S&P 500 to make sure it continuously reflects the U.S. economy. Updates are usually made on a quarterly basis, but sometimes additional adjustments might occur due to mergers, acquisitions, or changes in company market cap.

Between 1962 and 2014, more than 1,100 companies were replaced within the index. There have been 12 changes so far in 2025 alone, including:

• Robinhood Markets replacing Caesars Entertainment, due to market cap change
• Interactive Brokers replacing Walgreens Boots Alliance, following the company’s acquisition by Sycamore Partners, a private company
• Coinbase replacing Discover Financial Services after it was acquired by Capital One Financials, which is already a S&P 500 component.

How the S&P 500 is calculated

The S&P 500 uses a free-float market capitalization weighting method, which means that each company’s weight is based on its total market cap adjusted for shares available to the public.

The formula is:

• Company Weighting in S&P = (Company Market Cap) / (Total of All Market Caps)
• To calculate the total index value, the adjusted market caps of all 500 constituents are added and divided by a proprietary divisor. The divisor standardizes the index and ensures continuity when there are corporate actions like stock splits or share issuances.
• Note that the index only accounts for free-floating shares, which are those publicly available for trading. This means insider or institutional holdings are excluded.

S&P 500 eligibility criteria

To be included in the S&P 500, a company must:

• Have a market capitalization of at least $22.7 billion
• Be domiciled and publicly listed in the United States
• Maintain a public float of at least 50% of its shares
• Have traded at least 250,000 shares per month for the previous six months
• Reported positive earnings for the most recent quarter and over the past four consecutive quarters
• Be structured as a U.S. corporation (REITs are eligible, but partnerships, ETFs, and preferred shares are not).

These factors, as well as liquidity, profitability, and sector representation, are all taken into account by the committee when choosing companies. Ultimately, the committee can use its own discretion to maintain a representative balance of the U.S. economy, so it may stray from these rules if it deems necessary

S&P 500 trading hours

The S&P 500 shares the same trading hours as other U.S. stock exchanges:

• Pre-market hours are between 4:00 a.m. and 9:30 a.m. ET (08:00 to 13:30 UTC)
• Regular trading hours are between 9:30 a.m. and 4:00 p.m. ET (13:30 to 20:00 UTC)
• After-hours trading is available between 4:00 p.m. and 8:00 p.m. ET (20:00 to 00:00 UTC).

Keep in mind that pre-market and after-hours trading sessions tend to have lower liquidity and wider spreads, which can lead to more volatile price movements. You can also trade S&P 500 futures nearly 24 hours a day on the Chicago Mercantile Exchange (CME).

Factors that move the S&P 500 price

The S&P 500 generally reflects the health of the U.S. economy – when American businesses are performing well, the index typically rises, and when they struggle, it tends to fall. All in all, factors that move the S&P 500 include fundamental data, company performance, and market crashes and global events.

Fundamental data

Some important fundamentals to follow include:

• Interest rates: Lower interest rates generally support corporate growth by reducing borrowing costs and encouraging consumer spending. When interest rates rise, borrowing becomes more expensive and often puts pressure on stock prices.
• Inflation: High inflation can squeeze profit margins and lead to higher interest rates as the Federal Reserve attempts to cool the economy. When inflation expectations rise, investors may sell their stocks, causing the S&P 500 to decline.
• Employment: High employment levels are usually positive for consumer spending, but extremely tight labor markets can pressure wages and lead to higher inflation. This in turn can prompt rate hikes and weigh on stocks, and therefore the S&P.

Individual company performance

Because the S&P 500 is market-cap weighted, larger companies have more influence over its movements. That said, since there are so many constituents, it’s less likely for a single company to cause a major swing on the S&P as it is with other benchmarks. For example, Nvidia’s weighting is about 7% on the S&P 500 compared to roughly 13% on the Nasdaq-100.

Still, the top 15 constituents of the S&P 500 account for nearly half of the index’s daily movement.

Market crashes and global events

Sometimes, external events can provoke massive market selloffs and send the S&P 500 crashing. One example of this happening is ‘Black Monday’ in 1987, when the index fell nearly 20% in a single day. Similar selloffs occurred during the 2008 Financial Crisis and the COVID-19 pandemic in 2020.

S&P 500 price history and returns

• Since its launch in 1957, the S&P 500 has achieved an average annual total return of around 10.54% (or about 6.68% if you account for inflation). Of course, this doesn’t mean that the index grows by 10% every year – some years see double digit gains while others see declines.
• During the 2008 Global Financial Crisis, for example, the S&P 500 dropped nearly 50% between August 2008 and March 2009. In 2024, the index rose 23% and has set multiple record highs throughout 2025.
• Despite several sharp downturns over the years, the index has posted annual increases about 70% of the time with around 5% of all trading days recording all-time highs.

Average returns over time

The table below shows the S&P 500’s average returns, as of December 2024:

Source: NerdWallet

Ways to trade the S&P 500

You can’t buy shares of the S&P 500 directly, but you can gain exposure to the index through futures & options, CFDs, and ETFs.

S&P 500 futures & options

Futures and options contracts allow you to speculate on or hedge against future changes in the S&P 500’s value, without needing to own the underlying stocks:

• Futures are standardized agreements to buy or sell the index at a specific price on a future date. If the index rises above your contracted price, you profit from the difference, while if it falls you take a loss.
• Options work similarly to futures, only you have the right and not the obligation to buy or sell the index before expiration. This gives you more flexibility.

You can trade S&P 500 futures and options on the Chicago Mercantile Exchange (CME).

S&P 500 ETFs and index funds

The easiest way to invest in the S&P 500 is through an exchange-traded fund (ETF) or index mutual fund that mirrors the index’s composition. These funds hold the same stocks as the S&P 500, weighted in the same proportions.

Popular S&P 500 ETFs include:

• SDPR S&P 500 ETF Trust (SPY)
• Vanguard S&P 500 ETF (VOO)
• iShares Core S&P 500 ETF (IVV).

You can buy and sell ETFs on regular exchanges, just like individual stocks. Index mutual funds, however, are priced just one a day after the market closes.

S&P 500 CFDs

Like futures and options, contracts for difference (CFDs) allow you to speculate on the S&P’s price movements without owning any of the underlying stocks. You can go long (buy) if you expect the index to rise, or go short (sell) if you think it will fall.

CFDs are leveraged instruments, which means you only need to deposit a fraction of the trade’s total value to open a position. This can amplify both profits and losses, so they’re more suitable for experienced traders who can apply careful risk management strategies.

Direct investment in S&P 500 companies

You can technically replicate the S&P 500’s performance by buying shares of all 500 companies listed on the index, but this would require significant capital and constant rebalancing.

S&P 500 vs other indices

Besides the S&P 500, the two other main U.S. stock market benchmarks are the Dow Jones Industrial Average (DJIA) and Nasdaq Composite. Below, we look at how the S&P compares to these two indices as well as the Russell Indexes.

S&P 500 vs. Dow Jones Industrial Average (DJIA)

The Dow Jones Industrial Average, often just called the Dow, is one of the oldest stock market indices. Unlike the S&P 500, the DJIA includes just 30 companies, providing less broad exposure to different sectors of the U.S. economy.

The Dow is also price-weighted, which means companies with higher-priced stocks have more influence on the index, regardless of their size. The S&P, however, is market-cap weighted, giving more weight to companies with larger market values.

S&P 500 vs. Nasdaq

The Nasdaq Composite Index tracks more than 2,500 companies listed on the Nasdaq Stock Exchange, which includes both U.S. and international firms.

One of the main differences, besides the number of companies, is that the Nasdaq Composite is heavily weighted towards technology stocks of varying sizes while the S&P tracks large-cap companies across all sectors. This means the Nasdaq often experiences greater volatility and faster growth during tech-driven rallies, while the S&P 500 offers more balanced exposure.

The Nasdaq-100 Index is a subset of the Nasdaq Composite, tracking 100 of the largest non-financial companies listed on the Nasdaq exchange.

S&P 500 vs. Russell Indexes

The Russell family of indexes measures performance across different segments of the U.S. stock market, with the most well-known being the Russell 1000, Russell 2000, and Russell 3000.

The S&P 500 and Russell indexes both use market-cap weighting, but the way they choose the components is different. The S&P uses a committee-based selection process while the Russell indexes are strictly rule-based, meaning membership is automatically decided based on company size.

Advantages and risks of trading the S&P 500

Some potential advantages of trading the S&P 500 include:

• Diversification: The S&P 500 includes 500 large-cap companies across 11 major sectors, providing built-in diversification and reducing company or sector-specific risk.
• High liquidity: S&P-linked products, like ETFs and futures, are some of the most traded instruments in the world. This often leads to tighter spreads and faster execution.
• Strong long-term returns: Historically, the S&P 500 has delivered average annual returns of about 10%, making it a reliable long-term investment.

Some potential risks of investing in the S&P 500 include:

• Concentration in large-cap stocks: Even though it’s well-diversified, the S&P is still heavily influenced by its largest components (e.g. Nvidia, Microsoft, and Apple). If these companies decline, the index can go down with them.
• Market overvaluation: In market-cap weighted indices like the S&P 500, overvalued stocks can inflate the value of the index, even if their fundamentals don’t justify the valuation.
• Global economic shocks: The S&P 500 isn’t immune to events like recessions, geopolitical conflicts, or financial crises, all of which can lead to potential drawdowns and volatility.