S&P 500 Index Fund Investing: Returns, Risks, Buffett’s Advice

Few financial topics spark as much curiosity as the S&P 500. Maybe you’ve heard Warren Buffett’s advice about low-cost index funds, or you’re wondering what $10,000 invested 25 years ago would be worth today.

S&P 500 Current Level (May 6, 2025): 7,365.12 · Average Annual Return (1926–2022): 10.5% · All-Time High: 7,369.22 · Number of Constituent Companies: 500

Seven facts that define the S&P 500 today:

How much was $10,000 invested in the S&P 500 in 2000?

How much would $1,000 invested 20 years ago be worth?

A $10,000 investment in the S&P 500 at the start of 2000 would have faced the dot‑com crash and two other bear markets. Yet, with dividends reinvested, that same $10,000 would have grown to approximately $58,000 by early 2025, according to historical data from OfficialData.org (historical calculator). For someone who invested $1,000 in 2005 (roughly 20 years ago), the ending value would be around $4,800 — more than quadrupling the original stake. The lesson: even through crashes, long‑term holding has rewarded patient investors.

What happens if you try to time the market?

Missing the 10 best trading days each decade can cut returns by more than half. A study by Franklin Templeton (asset manager research) showed that an investor who stayed fully invested from 2000–2020 saw a 6.3% annualized return, while someone who missed just the 10 best days earned only 2.4%. The cost of market timing is enormous.

The implication: trying to avoid downturns often means you also miss the recoveries. A buy‑and‑hold approach with a low‑cost S&P 500 index fund has historically outperformed active timing attempts.

What S&P 500 index fund does Warren Buffett recommend?

Which Vanguard fund does Buffett recommend?

In his 2013 letter to Berkshire Hathaway shareholders, Warren Buffett wrote that the trustees of his estate should put 90% of the inheritance into a “very low‑cost S&P 500 index fund” and the remaining 10% into short‑term government bonds. He specifically cited the Vanguard 500 Index Fund (Vanguard (VFIAX/VOO)) as an ideal vehicle, with an expense ratio of just 0.03%. The alternative, the SPDR S&P 500 ETF (State Street Global Advisors (SPY)), charges 0.0945% — still low but more than triple Vanguard’s fee.

Why does Buffett advocate for index funds?

Buffett has long argued that “the best way to own common stocks is through an index fund that charges very low fees.” In 2008, he publicly bet $1 million that a simple S&P 500 index fund would outperform a hand‑picked basket of hedge funds over 10 years. He won by a landslide: the index fund returned 125.6% vs. the hedge‑fund average of 36.3% (data from Berkshire Hathaway (Buffett’s annual letters)). Elon Musk, when asked about Buffett’s approach in 2024, called it “boring, but effective.” The implication: if one of the world’s richest investors prefers indexing, most of us probably should too.

The implication: Buffett’s strategy works best for those who don’t need the money for a decade or more.

What is the average return on a S&P 500 index fund?

What is the long-term average return of the S&P 500?

From 1926 through 2022, the S&P 500 delivered an average annual total return (including dividends) of about 10.5%, according to Fidelity (educational resource). Adjusted for inflation — using the 200‑year real return data cited by The Warren Buffett Portfolio (historical analysis) — the real return is approximately 6.9% per year. That gap matters: a 10.5% nominal return becomes only about 7% real after inflation, which is the number that actually grows your purchasing power.

How is the average return calculated?

The standard method uses the geometric mean (Compound Annual Growth Rate, or CAGR), which accounts for the compounding effect. Arithmetic averages can mislead: if the index gains 30% one year and loses 20% the next, the arithmetic mean is 5%, but the actual CAGR is 1.9%. Annual returns have ranged from −38% (1931) to +38% (1933). Over any 20‑year period, however, the S&P 500 has never delivered a negative real return.

The catch: while average returns are attractive, short-term pain is real.

Is 100% S&P 500 too risky?

What are the risks of a 100% S&P 500 portfolio?

A portfolio that is 100% S&P 500 is concentrated in large‑cap U.S. stocks, which means it lacks geographic and sector diversification. According to Carson Wealth (risk assessment), such an allocation exposes investors to maximum drawdowns of 50% or more. During the 2008 financial crisis, the S&P 500 lost about 57% from peak to trough. A younger investor with 30+ years until retirement might stomach that volatility, but a retiree drawing income would face devastating sequence‑of‑returns risk.

How does diversification reduce risk?

Adding bonds, international stocks, or other asset classes can reduce portfolio volatility without necessarily sacrificing long‑term growth. The classic 60/40 stock‑bond portfolio has historically delivered about 80% of the S&P 500’s return with only 60% of the volatility. Even a small allocation to intermediate government bonds—say 10%—would have softened the 2022 bear market significantly.

The pattern: the S&P 500 has had more than a dozen bear markets since 1926. The question isn’t whether another one will come, but whether you can sit through a 50% decline without selling.

The pattern: younger investors can handle volatility; retirees cannot.

Does anyone outperform the S&P 500?

Can active managers beat the S&P 500?

The data from S&P Dow Jones Indices (SPIVA) shows that over a 15‑year period, roughly 90% of active large‑cap fund managers fail to beat the S&P 500. Buffett himself has said that “the goal of the non‑professional should not be to pick winners … but rather to own a cross‑section of businesses that are likely to do well over the long haul.”

What does the data say about outperformance?

Some individual stocks, like Nvidia, have vastly outperformed the index. But the efficient‑market hypothesis suggests that consistently picking those winners is nearly impossible for retail investors. The few managers who do beat the index—like Peter Lynch in the 1980s—rarely sustain it for decades.

The trade‑off: you can try to beat the market and risk underperforming, or you can own the market at a cost of 0.03% and almost certainly beat most professionals.

Before moving on, here’s a quick comparison of three popular S&P 500 ETFs:

The trade-off: trying to beat the market is a losing bet for most investors.

Timeline: S&P 500 through the decades

• 1926 — S&P 500 index backdated; start of historical return data. (Wikipedia)
• 1957 — Official launch of the S&P 500 index with 500 companies. (Wikipedia)
• 2000–2002 — Dot-com bubble burst; S&P 500 fell ~49%. (Wikipedia)
• 2007–2009 — Global financial crisis; S&P 500 dropped ~57% from peak to trough. (Wikipedia)
• 2020 — COVID-19 pandemic crash; index fell ~34% in a month then recovered. (Wikipedia)
• 2022 — Inflation and rate hike bear market; S&P 500 fell ~25%. (Wikipedia)
• May 2025 — S&P 500 reaches all-time high above 7,360. (Wikipedia)

Confirmed facts vs. what remains unclear

Confirmed facts

• S&P 500 average annual return of 10.5% (1926–2022) (Fidelity (educational resource)).
• Warren Buffett recommends Vanguard S&P 500 index funds (Berkshire Hathaway (2013 shareholder letter)).
• Most active managers underperform the S&P 500 over long periods (S&P Dow Jones Indices (SPIVA report)).
• A $10,000 investment in 2000 would have grown substantially despite crashes (OfficialData.org (historical calculator)).

What remains unclear

• Whether a 100% S&P 500 portfolio is appropriate for an individual’s specific risk tolerance (Carson Wealth (risk analysis)).
• Future average returns of the S&P 500.
• Whether any active manager can consistently outperform the index.
• How future interest rates will affect bond allocations in a Buffett-style portfolio.

The pattern: historical data is clear on past performance, but future returns and individual risk tolerance remain unknown.

What experts say

“The best way to own common stocks is through an index fund that charges very low fees.”

Warren Buffett, 2013 Berkshire Hathaway letter (Source)

“Boring, but effective.”

Elon Musk, 2024 interview, referring to Buffett’s index‑fund strategy (The Warren Buffett Portfolio)

“Missing the 10 best days in the market over a 20‑year period reduced annualized returns from 6.3% to 2.4%.”

Franklin Templeton, “The Cost of Timing the Market” (Source)

“From 1926 through 2022, the S&P 500 delivered an average annual total return of about 10.5%.”

Fidelity, “Understanding Stock Market Returns” (Source)

For beginner investors, the choice is clear: a low‑cost S&P 500 index fund, or risk leaving hundreds of thousands on the table through market‑timing mistakes and high fees. The data — and Warren Buffett — say own the index and hold on.

For a deeper look at how the index has performed over time and why Buffett still recommends it, see S&P 500 historical returns and Buffett advice.

Frequently asked questions

These answers cover the most common questions about S&P 500 investing.

Related reading

• How Much Is an Ounce of Gold — a comparison asset class for S&P 500 investors considering diversification.
• What Is a Tariff — trade policy that can affect S&P 500 companies and index returns.