What Is the S&P 500—and Why It Matters
The S&P 500 is an index of approximately 500 of the largest U.S. companies, weighted by their market capitalization. It’s curated by a committee at S&P Dow Jones Indices and designed to represent the U.S. large-cap equity market. Investing in the S&P 500 is effectively a way to own a slice of the American corporate economy—tech, healthcare, financials, industrials, consumer goods, and more—without trying to pick individual stocks.
How the Index Works
- Market-cap weighting: Bigger companies exert more influence on performance. If mega-cap technology or healthcare stocks rally, the index often rises strongly.
- Eligibility rules: Companies must meet criteria for size, liquidity, profitability, and U.S. domicile to be considered, and changes are announced periodically.
- Rebalancing: The index is rebalanced and updated to reflect corporate actions like mergers, spin-offs, and new entrants, maintaining a representative slice of the market.
- Diversification—but not uniform: The S&P 500 spans sectors, but it can be concentrated in the largest names. This provides convenience and breadth with some top-heavy risk.
Historically, the S&P 500 has delivered an average annual return in the high single digits to low double digits over long periods, though year-to-year returns can vary widely. That volatility is the tradeoff for long-term growth potential.
Why Beginners in 2025 Are Choosing the S&P 500
Today’s investing environment is uniquely friendly to newcomers. Most major brokerages offer $0 commissions on U.S. stock and ETF trades, low-cost index funds are abundant, and fractional share investing means you can start with small amounts. The S&P 500 is also a cornerstone in many retirement accounts, robo-advisors, and target-date funds, making it easy to set and forget.
- Automation and access: Recurring deposits, automatic reinvestment of dividends, and prebuilt portfolios simplify the process.
- Liquidity and transparency: S&P 500 ETFs trade all day, with tight bid-ask spreads and daily portfolio disclosures.
- Tax efficiency: Broad index funds are typically tax efficient (especially ETFs), helping you keep more of your returns.
However, investors should recognize 2025 realities: the index is heavily influenced by leading mega-cap companies, interest rates (which affect valuations), and corporate earnings growth. Short-term volatility—including pullbacks, bear markets, and sharp reversals—remains part of the journey.
All the Ways to Invest in the S&P 500
There isn’t just one way to buy the S&P 500. Different paths cater to different needs, from hands-on trading to automated set-and-forget investing. Below are the main options for anyone searching how to invest in the S&P 500 in 2025.
1) S&P 500 ETFs
Exchange-traded funds (ETFs) are the simplest, most popular vehicles. They trade like stocks on exchanges throughout the day, allowing intraday price discovery and flexibility. Widely used S&P 500 ETFs include:
- SPY (SPDR S&P 500 ETF Trust)
- VOO (Vanguard S&P 500 ETF)
- IVV (iShares Core S&P 500 ETF)
- SPLG (SPDR Portfolio S&P 500 ETF)
All track the same index with minor structural differences. Consider:
- Expense ratio: A small annual fee embedded in the fund. Popular S&P 500 ETFs are known for very low costs. Check each fund’s current prospectus.
- Liquidity and spreads: Highly traded ETFs may have tighter bid-ask spreads, reducing trading costs.
- Dividend policy: Most distribute quarterly. You can enable automatic reinvestment (DRIP) at your broker.
- Taxes: ETFs are generally tax efficient. In taxable accounts, dividends and any realized gains are taxable. Consult a tax professional for your situation.
2) S&P 500 Index Mutual Funds
If you prefer automatic investing without worrying about trading times, an index mutual fund may suit you. Examples include:
- VFIAX (Vanguard 500 Index Fund Admiral Shares)
- FXAIX (Fidelity 500 Index Fund)
- SWPPX (Schwab S&P 500 Index Fund)
Key considerations:
- Expense ratio: Also very low for flagship index funds; always verify the current fees.
- Investment minimums: Some mutual funds have minimum initial investments; many platforms reduce or waive these for automatic contributions.
- Trading window: Mutual funds execute at the day’s closing NAV, not intraday, which simplifies the process and reduces the temptation to time markets.
3) Retirement Plans and the S&P 500
Workplace plans often include S&P 500 index options. For example:
- 401(k)/403(b)/457(b): Many plans offer a U.S. large-cap index fund that mirrors the S&P 500.
- TSP (Thrift Savings Plan): The C Fund tracks an S&P 500-like index, providing similar exposure for federal employees and military members.
- IRAs: In a Traditional or Roth IRA, you can buy S&P 500 ETFs or mutual funds of your choice with tax-deferred or tax-free growth potential (depending on the account type).
When deciding how to invest in the S&P 500 within retirement accounts, also consider employer matches, plan fees, and what other asset classes the plan offers for diversification.
4) Robo-Advisors and Managed Portfolios
Robo-advisors typically use ETFs (including broad U.S. equity funds) to build a diversified portfolio that often includes S&P 500 exposure. They handle rebalancing, tax-loss harvesting (in taxable accounts), and other tasks. This approach is ideal for investors who want automation and a portfolio that extends beyond the S&P 500 to include bonds, internationals, and cash.
Step-by-Step: How to Buy the S&P 500 in 2025
If you’re looking for a concrete walkthrough, use this process to get started—whether you prefer an ETF or a mutual fund, a brokerage account or a retirement account. These steps work for anyone asking how to invest in the S&P 500 index fund, how to buy the S&P 500 ETF, or simply how to get S&P 500 exposure in a portfolio.
- Choose your account type: Taxable brokerage for flexibility; IRA/Roth IRA for tax advantages; or your workplace plan for automated contributions. Confirm eligibility and contribution limits, and verify the latest IRS rules.
- Pick a trusted platform: Select a reputable broker or fund provider known for low fees, robust security, easy auto-deposits, and strong customer support.
- Select the S&P 500 vehicle: Decide between an ETF (e.g., VOO, IVV, SPY, SPLG) or a mutual fund (e.g., FXAIX, VFIAX, SWPPX). Compare expense ratios, minimums, and convenience features.
- Fund your account: Link a bank account and transfer money. Consider setting up automatic contributions to stay consistent.