What Is the S&P 500?
The S&P 500 (Standard & Poor's 500) is a market-cap-weighted index of 500 large US companies traded on NYSE or Nasdaq. S&P Global reviews the composition quarterly. Because it is cap-weighted, mega-cap names like Apple, Microsoft, and Nvidia have an outsized effect on the index's daily movement.
It is more than a “stock index.” Institutional investors, central banks, and pension funds worldwide use the S&P 500 as their primary benchmark. When analysts say the market is up or down, they almost always mean the S&P 500.
Inclusion Criteria
Sector Breakdown
The S&P 500 is divided into 11 GICS sectors. As of 2024, Information Technology accounts for roughly 30% of the index — meaning Apple, Microsoft, Nvidia, and Alphabet alone can move the index meaningfully on any given day.
Major Sector Weights (approx. 2024)
Historical Performance
The S&P 500's long-run annualized total return (including reinvested dividends) has been roughly 10–11%. After adjusting for inflation, the real return is approximately 7% per year — making it one of the most powerful long-term wealth-building tools available to individual investors.
It does crash. The dot-com bust (2000–02), the global financial crisis (2008–09), and the COVID shock (2020) each caused drawdowns exceeding 50%. But after every single bear market, the index recovered and set new all-time highs.
📊 Key Statistics
Long-run annualized return
~10–11%
$10,000 invested 30 years
~$174,000
Worst peak-to-trough
−56.8% (2009)
Avg. recovery time
~2–3 years
S&P 500 vs Nasdaq vs Dow
The three major US indices serve different purposes and include different stocks.
S&P 500
500 large-cap US companies across all sectors. The broadest and most representative benchmark. Used by institutional investors worldwide.
Nasdaq Composite
All stocks listed on the Nasdaq exchange — heavily skewed toward tech and growth. More volatile than the S&P 500; outperforms in bull markets, underperforms in downturns.
Dow Jones Industrial Average
Just 30 large, established US companies, price-weighted. The oldest index (since 1896), but considered less representative than the S&P 500 for portfolio benchmarking.
How to Invest in the S&P 500
Individual investors access the S&P 500 primarily through ETFs. All three options below track the same index; the main differences are expense ratio and liquidity profile.
Major S&P 500 ETFs
SPY
SPDR S&P 500 ETF Trust
Expense ratio 0.09% · World's largest ETF by AUM; most liquid
VOO
Vanguard S&P 500 ETF
Expense ratio 0.03% · Lowest expense ratio; popular for long-term DCA
IVV
iShares Core S&P 500 ETF
Expense ratio 0.03% · Run by BlackRock; near-identical to VOO
For long-term investing, VOO or IVV are the most cost-efficient choices. The fee difference from SPY compounds meaningfully over decades.
Cap-Weighting and Market Breadth
Because the S&P 500 is cap-weighted, the top 10 holdings can represent 30–35% of the index. When mega-cap tech is strong, the headline number looks great even if most of the other 490 stocks are flat or down. This gap between the index and its average member is called market breadth.
There is also an equal-weight S&P 500 ETF (RSP). It reduces mega-cap concentration, but adds more exposure to smaller companies and tends to behave differently during momentum-driven markets. For most beginners, the standard cap-weighted index is the simpler starting point.
Total Return vs. Price Return
When you read “the S&P 500 returned 10% per year,” that figure almost always includes reinvested dividends. Price-only return is lower. ETF holders receive dividends as cash (subject to withholding tax) or reinvestment depending on brokerage settings.
When comparing historical results, distinguish “price return” from “total return.” Korean investors must also account for dividend withholding tax and capital gains tax, which reduce the net return below the headline backtest figure. See the US Stock Tax guide for details.
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