Turn on any financial news channel and within a minute someone mentions "the S&P." When people say "the market was up today," this index is usually what they mean.
So what's the S&P 500, exactly? It is a stock market index that tracks about 500 of the largest publicly traded companies in the United States. It is not a company you can buy shares of directly, but you can invest in funds that copy it, and millions of people build their retirement on exactly that.
What's the S&P 500, Exactly?
The S&P 500, short for Standard & Poor's 500, is maintained by S&P Dow Jones Indices. Launched in its modern form in 1957, it measures the combined performance of roughly 500 large U.S. companies. Because some companies list more than one share class, the index technically contains slightly more than 500 stocks.
Those companies together represent roughly 80% of the total value of the U.S. stock market. That breadth is why the S&P 500 is treated as the standard benchmark for U.S. stocks, and why fund managers measure themselves against it.
You will recognize most of the names inside it: Apple, Microsoft, Nvidia, Amazon, and Alphabet have all ranked among its largest holdings in recent years, alongside banks, oil producers, retailers, drugmakers, and utilities across 11 sectors.
How Companies Get Into the Index
A committee at S&P Dow Jones Indices decides what goes in. To qualify, a company generally must be a U.S. company, meet a multi-billion-dollar market value threshold that the committee updates over time, have strong trading liquidity, and show positive earnings in its most recent quarter and over the trailing year.
Companies get added and removed regularly as businesses grow, shrink, merge, or get acquired. That quiet self-cleaning is part of the index's appeal: yesterday's giants fade out and rising companies take their place without you doing anything.
How the Index Is Weighted
The S&P 500 is weighted by market capitalization, meaning bigger companies move the index more. A 2% move in a $3 trillion company affects the index far more than a 2% move in a $20 billion one.
This has a side effect worth knowing: the largest handful of technology companies have recently made up roughly a third of the entire index's value. When you buy an S&P 500 fund, you are more concentrated in a few giant stocks than the number 500 suggests.
What Has the S&P 500 Returned Historically?
Since 1957, the S&P 500 has averaged roughly 10% per year with dividends reinvested, based on historical index data as of July 2026. Adjusted for inflation, the long-run average works out to about 6.5% per year.
Averages smooth over a rough ride. The index lost more than a third of its value in 2008, and it has also posted single years with gains above 25%. Drops of 10% or more happen fairly often, and past performance never guarantees future results.
The practical takeaway: the S&P 500 has rewarded patient, multi-decade investors historically, but it punishes anyone who needs their money back on a deadline.
How to Invest in the S&P 500
You cannot buy the index itself, but you can buy funds designed to match it. There are two main wrappers:
- Index mutual funds. Often used inside 401(k) plans, priced once per day.
- ETFs (exchange-traded funds). Trade like stocks all day. Well-known S&P 500 ETFs from major providers charge expense ratios of roughly 0.03% to 0.09% per year.
Getting started takes three steps: open a brokerage account, search for an S&P 500 index fund or ETF, and set up a recurring buy. Fractional shares mean you do not need the full share price to begin.
Robinhood makes this simple with commission-free trades, fractional shares starting at $1, and retirement accounts that offer a contribution match for eligible members, so your S&P 500 fund can live inside an IRA.
Robinhood
Robinhood
Robinhood is a trading platform that brings stocks, ETFs, options, futures, prediction markets, crypto, and retirement accounts together in one app.
Standout feature
One platform for stocks, ETFs, options, futures, prediction markets, and crypto
Fees
$0 commission on stocks, ETFs, and options.
Pros
Zero-commission trading on stocks, ETFs, and options
Cons
Best perks (high APY, lower margin rates) require Gold subscription ($5/month)
Public is another solid option. It supports stocks, bonds, options, and fractional investing, and it adds plain-English context around each fund, which is useful when you are comparing S&P 500 ETFs for the first time.
Public
Public
Investing for those who take it seriously. Invest in stocks, bonds, options, crypto & more.
Standout feature
A 5%+ yield Bond Account paired with 3.3% APY on cash — Public is one of the only consumer apps where idle and conservative money is treated as seriously as the equity portfolio.
Fees
Free
Pros
• Invest in stocks, bonds, crypto & more• Earn 3.3% APY* on your cash with no fees• 1% match when you transfer your portfolio• Lock in a 5%+ yield with a Bond Account
Cons
Customer support is in-app and email only, no phone
S&P 500 vs. Dow vs. Nasdaq
The three indexes you hear about daily measure different things. The Dow Jones Industrial Average tracks only 30 large companies and weights them by share price, which is why professionals rely on it less. The Nasdaq Composite tracks thousands of stocks listed on the Nasdaq exchange and leans heavily toward technology.
The S&P 500 sits in the middle: broad enough to represent the whole U.S. large-company market, selective enough to stay high quality. That balance is why it became the default benchmark.
Risks to Understand Before You Invest
An S&P 500 fund is diversified across companies, but it is not diversified across everything. It holds only large U.S. stocks, so it skips small companies, international markets, and bonds entirely.
It also cannot protect you from a broad market decline, since it is the broad market. If stocks fall 30%, your fund falls about 30%. That is why most guidance suggests only investing money you will not need for at least five years, and pairing stock funds with safer assets as you approach a goal.
None of this is personalized financial advice, and terms and conditions apply to any brokerage you use. But as a first building block for long-term investing, few products are as widely recommended as a low-cost S&P 500 index fund. Open an account, start a small recurring investment, and let time do the compounding.
Frequently Asked Questions
Is the S&P 500 a good investment for beginners?
Many financial professionals consider a low-cost S&P 500 index fund a reasonable core holding for beginners because it spreads money across hundreds of companies in one purchase. It still carries full stock market risk, so it fits long-term goals better than short-term ones.
How much money do I need to invest in the S&P 500?
With fractional shares, you can start with as little as $1 at many brokerages. Consistency matters more than the starting amount, and a small automatic monthly investment is how most people build a position over time.
Does the S&P 500 pay dividends?
The index itself does not, but many companies inside it do. S&P 500 funds collect those dividends and pass them to you, and you can choose to reinvest them automatically to buy more shares.
What is the difference between the S&P 500 and a total market fund?
A total market fund holds thousands of U.S. stocks, including small and mid-sized companies, while the S&P 500 holds only about 500 large ones. Their long-term performance has historically been similar because large companies dominate both.
