What Is the S&P 500?
The S&P 500 (Standard & Poor's 500) is a stock market index that tracks the performance of approximately 500 of the largest publicly traded companies in the United States. It is widely regarded as the single best gauge of large-cap US equities and serves as the benchmark against which most professional fund managers measure their performance.
The index was introduced in its current form in 1957 by Standard & Poor's, though earlier versions of the index date back to the 1920s. Today, the S&P 500 covers roughly 80% of the total US stock market by capitalization, making it an efficient way to gain exposure to the broad American economy through a single investment.
The S&P 500 is a market-capitalization-weighted index, which means that larger companies have a greater influence on the index's performance than smaller ones. For example, a company like Apple or Microsoft, with a market cap in the trillions of dollars, carries far more weight than a company at the bottom of the index with a market cap of only a few billion dollars. A committee at S&P Dow Jones Indices selects which companies are included based on criteria such as market capitalization, liquidity, domicile, financial viability, and sector representation. The index is not simply the 500 largest companies by market cap; the selection committee exercises judgment to ensure the index represents the leading industries in the US economy.
S&P 500 at a Glance
- Number of holdings: Approximately 500 large-cap US stocks (503 as of early 2025 due to multiple share classes)
- Weighting method: Float-adjusted market-capitalization weighted
- Coverage: Approximately 80% of total US stock market value
- Inception: March 4, 1957 (in its current 500-stock form)
- Index provider: S&P Dow Jones Indices
- Rebalancing: Quarterly (March, June, September, December)
Because of its breadth and the quality of the companies it contains, the S&P 500 has become the default starting point for millions of investors. When financial commentators say "the market was up today," they are almost always referring to the S&P 500. Its long history and transparent methodology make it one of the most studied and trusted benchmarks in the world.
S&P 500 Historical Performance
The S&P 500 has delivered an average annual return of approximately 10% since its inception in 1957, including dividends. After adjusting for inflation, the real return has averaged roughly 7% per year. These long-term averages, however, mask enormous variation from year to year. Understanding the range of historical outcomes is essential for setting realistic expectations and staying disciplined during turbulent periods.
In its best calendar years, the S&P 500 has returned over 30%. In its worst years, the index has declined by more than 35%. These extremes are not anomalies; they are a normal part of how stock markets behave. The key insight for long-term investors is that despite these dramatic swings, the overall trajectory of the S&P 500 has been strongly upward over every multi-decade period in its history.
| Period / Event | S&P 500 Performance | Recovery Time |
|---|---|---|
| Long-term average (1957-2024) | ~10% annualized (nominal) | N/A |
| Best single year (1995) | +37.6% | N/A |
| Worst single year (2008) | -37.0% | ~4 years to recover |
| Dot-com crash (2000-2002) | -49% peak to trough | ~7 years to recover |
| Financial crisis (2007-2009) | -57% peak to trough | ~5.5 years to recover |
| COVID crash (Feb-Mar 2020) | -34% peak to trough | ~5 months to recover |
| 20-year average (2005-2024) | ~10.5% annualized | N/A |
The recovery times listed above refer to how long it took the index to return to its previous peak on a price basis. Including reinvested dividends, recovery times are somewhat shorter. The critical takeaway is that every major decline in S&P 500 history has eventually been followed by a full recovery and new all-time highs. Investors who remained invested and continued making regular contributions during downturns were rewarded with strong long-term returns. Those who panicked and sold during declines often locked in losses and missed the subsequent recovery.
Ways to Invest in the S&P 500
You cannot invest directly in the S&P 500 index itself. Instead, you invest through funds that track the index. These come in two main formats: exchange-traded funds (ETFs) and index mutual funds. Both aim to replicate the performance of the S&P 500 as closely as possible, but they differ in how you buy them, their fee structures, and their minimum investment requirements.
The following table compares the most popular S&P 500 index funds and ETFs available to individual investors. All of these are excellent choices, and the differences between them are small. The best fund for you depends primarily on which brokerage you use and whether you prefer the ETF or mutual fund format.
| Fund | Type | Expense Ratio | Minimum Investment | AUM (Approx.) | Provider |
|---|---|---|---|---|---|
| VOO (Vanguard S&P 500 ETF) | ETF | 0.03% | Price of 1 share | $500B+ | Vanguard |
| IVV (iShares Core S&P 500 ETF) | ETF | 0.03% | Price of 1 share | $500B+ | BlackRock (iShares) |
| SPY (SPDR S&P 500 ETF Trust) | ETF | 0.0945% | Price of 1 share | $550B+ | State Street |
| SWPPX (Schwab S&P 500 Index Fund) | Mutual Fund | 0.02% | No minimum | $90B+ | Charles Schwab |
| FXAIX (Fidelity 500 Index Fund) | Mutual Fund | 0.015% | No minimum | $500B+ | Fidelity |
A few important notes about the funds above. SPY is the oldest and most heavily traded S&P 500 ETF, making it popular with institutional investors and active traders due to its high liquidity. However, its expense ratio is higher than VOO and IVV, making it slightly less cost-efficient for long-term buy-and-hold investors. SWPPX and FXAIX are mutual fund options with no minimum investment requirements, making them particularly accessible for investors who want to set up automatic recurring contributions with exact dollar amounts. FXAIX has one of the lowest expense ratios of any S&P 500 fund at 0.015%, meaning you pay just $1.50 per year for every $10,000 invested.
Step-by-Step: How to Buy an S&P 500 Fund
Investing in the S&P 500 is straightforward. Here is a five-step process that takes most people less than an hour to complete.
Step 1: Open a Brokerage Account
If you do not already have one, open an account with a reputable brokerage such as Vanguard, Fidelity, Charles Schwab, or another major provider. You will need to decide between a taxable brokerage account and a tax-advantaged retirement account (such as a traditional IRA, Roth IRA, or 401(k)). If your employer offers a 401(k) with an S&P 500 index fund option, that is often the best place to start because of employer matching contributions and tax benefits. For more details, see our guide on how to open a brokerage account.
Step 2: Decide How Much to Invest
Determine how much money you can invest initially and how much you can contribute on a regular basis. There is no universally correct amount. The key principle is to invest money you will not need for at least five years, ideally ten or more. Many S&P 500 funds have no minimum investment, so you can start with whatever amount fits your budget. Even $50 or $100 per month, invested consistently over decades, can grow into a significant sum thanks to compound growth.
Step 3: Choose Your S&P 500 Fund
Select one of the S&P 500 funds from the comparison table above. If you have a Fidelity account, FXAIX is a natural choice. For Schwab accounts, SWPPX works well. If you prefer an ETF for its trading flexibility and tax efficiency, VOO and IVV are both excellent at just 0.03% expense ratios. Do not overthink this decision. The performance differences between these funds are negligible over time.
Step 4: Place Your Order
For a mutual fund, log into your brokerage, search for the fund by ticker symbol, enter the dollar amount you wish to invest, and submit the order. Mutual fund orders execute at the end of the trading day at the fund's net asset value (NAV). For an ETF, search for the ticker symbol, choose the number of shares (or a dollar amount if your brokerage supports fractional shares), select a market order or limit order, and submit. ETF orders execute during market hours at the current market price.
Step 5: Set Up Automatic Contributions
The most important step is automating your investing. Set up recurring contributions on a schedule that aligns with your pay cycle, whether weekly, biweekly, or monthly. Automatic investing ensures you contribute consistently regardless of market conditions, takes emotion out of the process, and harnesses the power of dollar-cost averaging. Most brokerages make this easy to configure for both mutual funds and, increasingly, for ETFs with fractional share support.
S&P 500 ETF vs Mutual Fund
Both ETFs and mutual funds that track the S&P 500 will give you nearly identical returns over time. The choice between them comes down to how you prefer to invest and which features matter most to you.
| Feature | S&P 500 ETF (e.g., VOO) | S&P 500 Mutual Fund (e.g., FXAIX) |
|---|---|---|
| Trading | Trades throughout the day at market price | Trades once per day at end-of-day NAV |
| Minimum investment | Price of 1 share (or less with fractional shares) | Often no minimum (FXAIX, SWPPX: $0) |
| Automatic investing | Available at some brokerages | Easy to set up at all brokerages |
| Expense ratio | 0.03% (VOO, IVV) | 0.015% - 0.02% (FXAIX, SWPPX) |
| Tax efficiency | Slightly more tax-efficient (in-kind creation/redemption) | Slightly less tax-efficient |
| Dollar-amount investing | Requires fractional share support | Invest exact dollar amounts natively |
| Best for | Taxable accounts, flexibility, low cost | Retirement accounts, automatic contributions |
In a tax-advantaged retirement account like an IRA or 401(k), the tax efficiency advantage of ETFs is irrelevant because you are not paying capital gains taxes within these accounts. In that case, a mutual fund's ability to invest exact dollar amounts and easily automate contributions may make it the more convenient choice. In a taxable brokerage account, the ETF structure can provide a small tax advantage because of how ETFs handle share creation and redemption, which minimizes taxable capital gains distributions.
For most long-term investors, the difference between an S&P 500 ETF and an S&P 500 mutual fund is negligible. Choose whichever format is most convenient at your brokerage and commit to investing consistently. To learn more about ETFs in general, visit our ETF investment basics guide.
S&P 500 vs Total Stock Market
One of the most common questions from new investors is whether to invest in an S&P 500 index fund or a total US stock market index fund. Both are excellent choices, and understanding the differences can help you decide which is right for your portfolio.
A total stock market fund (such as VTI, VTSAX, or FSKAX) holds not just the 500 largest companies but the entire universe of US publicly traded stocks, typically around 3,500 to 4,000 companies. This includes mid-cap and small-cap companies that are excluded from the S&P 500.
| Criteria | S&P 500 Index Fund | Total Stock Market Fund |
|---|---|---|
| Number of stocks | ~500 large-cap | ~3,500-4,000 (all caps) |
| Market coverage | ~80% of US market | ~100% of US market |
| Small/mid-cap exposure | None | Yes (~20% of holdings) |
| Historical returns | Very similar to total market | Very similar to S&P 500 |
| Availability in 401(k) plans | Very common | Common but less so |
| Diversification | Excellent (large-cap only) | Slightly better (all caps) |
In practice, the long-term performance of these two approaches has been remarkably similar because large-cap stocks dominate both by weight. The S&P 500 companies make up approximately 80% of a total stock market fund's value, so the returns are highly correlated. During periods when small-cap and mid-cap stocks outperform large caps, the total market fund will have a slight edge. During periods when large caps lead, the S&P 500 may perform marginally better.
If your 401(k) offers an S&P 500 fund but not a total market fund, that is perfectly fine. You are not missing out on meaningful returns. If you have access to both and want maximum diversification, the total market fund is the slightly broader choice. Either way, the most important decision is to invest consistently rather than to agonize over which of these two very similar options to choose. For a deeper dive into index strategies, see our index investing basics guide.
How Much to Invest in the S&P 500
There is no single correct answer to how much you should invest in the S&P 500 because it depends on your financial situation, goals, time horizon, and risk tolerance. However, some general principles can guide your decision.
First, make sure you have a solid financial foundation before investing. This means having an emergency fund covering three to six months of essential expenses, being free of high-interest debt (such as credit card balances), and having adequate insurance coverage. Investing in the stock market is a long-term endeavor, and you should only invest money you can afford to leave untouched for at least five to ten years.
Many financial planners suggest aiming to invest at least 15% to 20% of your gross income for retirement, including any employer matching contributions. For younger investors with a long time horizon, allocating a significant portion of that to S&P 500 or total stock market funds is a common and well-supported approach. As you approach retirement, gradually shifting a portion into bonds and other lower-risk investments helps protect your accumulated wealth.
If you are just getting started and 15% feels out of reach, start with whatever you can and increase your contributions over time. Investing $100 per month is far better than investing nothing while waiting until you can afford a larger amount. The habit of consistent investing matters more than the initial amount.
Tax Considerations
Where you hold your S&P 500 fund matters for tax purposes. Understanding the difference between taxable and tax-advantaged accounts can save you significant money over the long term.
Tax-Advantaged Accounts
401(k), 403(b), traditional IRA, and Roth IRA accounts offer tax benefits that can substantially boost your long-term returns. In a traditional 401(k) or IRA, your contributions may be tax-deductible, and your investments grow tax-deferred until you withdraw them in retirement. In a Roth IRA or Roth 401(k), you contribute after-tax dollars, but all future growth and withdrawals are completely tax-free. For most investors, maximizing contributions to tax-advantaged accounts before investing in a taxable brokerage account is the most efficient approach.
Taxable Brokerage Accounts
In a regular taxable brokerage account, you owe taxes on dividends received and on capital gains when you sell shares at a profit. S&P 500 index funds distribute dividends (typically quarterly), which are generally taxed as qualified dividends at the lower long-term capital gains tax rate. If you hold your investment for more than one year before selling, any gains are also taxed at the long-term capital gains rate, which is lower than ordinary income tax rates for most taxpayers.
S&P 500 ETFs tend to be slightly more tax-efficient than their mutual fund counterparts in taxable accounts because of the in-kind creation and redemption mechanism that minimizes taxable capital gains distributions. However, this advantage is relatively small for most individual investors. For a comprehensive overview, refer to our guide on tax-efficient investing.
Risks of S&P 500 Investing
While the S&P 500 has an excellent long-term track record, it is not a risk-free investment. Understanding these risks helps you make informed decisions and avoid costly mistakes during periods of market stress.
US-Only Concentration
The S&P 500 exclusively holds US companies. While many of these companies generate substantial revenue internationally, your investment is still concentrated in a single country's stock market. There have been extended periods (such as the 2000s decade) when international stocks significantly outperformed US stocks. A portfolio consisting solely of S&P 500 holdings misses diversification benefits from developed international and emerging market equities.
Large-Cap Bias
The S&P 500 only includes the largest companies, excluding small-cap and mid-cap stocks entirely. Small-cap stocks have historically delivered higher returns than large caps over very long time periods, though with greater volatility. Additionally, the market-cap weighting of the S&P 500 means that the top 10 holdings can represent 30% or more of the index, creating concentration risk in a handful of mega-cap technology companies.
No Bond Allocation
The S&P 500 is a 100% stock investment. It contains no bonds, cash, or other stabilizing assets. During severe market downturns, a portfolio consisting entirely of S&P 500 holdings can decline 30% to 50% or more. Investors who need income, have a shorter time horizon, or have lower risk tolerance should pair their S&P 500 holdings with bond funds or other fixed income investments to reduce portfolio volatility.
Market Downturns Can Last Years
While the S&P 500 has always recovered from downturns, those recoveries can take several years. After the dot-com crash, the index took approximately seven years to return to its previous peak. If you need your money within a few years, a 100% S&P 500 allocation may expose you to the risk of having to sell at a loss.
Important Reminder
Past performance does not guarantee future results. The S&P 500's historical average return of approximately 10% per year is not a promise of future returns. Markets can and do behave differently than they have in the past. All investing involves risk, including the possible loss of principal. Make investment decisions based on your own financial situation, goals, and risk tolerance.
Building a Portfolio Around the S&P 500
For many investors, an S&P 500 index fund serves as the core holding in their portfolio. However, a well-diversified portfolio typically includes additional asset classes beyond US large-cap stocks. Here are three sample portfolio allocations at different risk levels, all using the S&P 500 as the primary building block.
Aggressive Growth Portfolio (Long Time Horizon)
- 70% S&P 500 index fund (US large-cap stocks)
- 15% International stock index fund (developed & emerging markets)
- 10% Small-cap US stock index fund
- 5% Bond index fund
Balanced Portfolio (Moderate Risk Tolerance)
- 50% S&P 500 index fund (US large-cap stocks)
- 15% International stock index fund
- 5% Small-cap US stock index fund
- 25% Bond index fund (US aggregate)
- 5% International bond index fund
Conservative Portfolio (Shorter Time Horizon or Lower Risk Tolerance)
- 30% S&P 500 index fund (US large-cap stocks)
- 10% International stock index fund
- 40% Bond index fund (US aggregate)
- 10% Short-term bond or Treasury fund
- 10% International bond index fund
These sample allocations are starting points, not prescriptions. Your ideal allocation depends on your age, income stability, risk tolerance, and how many years until you need the money. A common rule of thumb is to subtract your age from 110 to determine your stock allocation percentage, though this is a rough guideline rather than a rigid rule. Regardless of which allocation you choose, the S&P 500 component provides exposure to the core of the US economy and has historically been the primary driver of long-term portfolio growth.
For more on constructing a diversified investment portfolio, explore our guides on how the stock market works and index investing basics.
