If you could only learn one investing concept, this might be the most important: are probably all you need.
What Is an ?
An index fund is a type of investment that automatically buys all the stocks (or bonds) in a particular market index. Instead of trying to pick winning stocks, you just buy the whole market.
Pro Tip
Think of it like this: instead of betting on one horse to win the race, you own a tiny piece of every horse. When the market goes up, you go up with it.
The Most Common Index Funds
S&P 500 Index Fund
- Owns the 500 largest U.S. companies
- Names you know: Apple, Microsoft, Amazon, Google
- One purchase = instant across 500 companies
Total Index Fund
- Owns virtually ALL U.S. publicly traded companies (3,000+)
- Large, medium, and small companies
- Even broader diversification than S&P 500
Total International Index Fund
- Owns companies from developed and emerging markets worldwide
- Geographic diversification outside the U.S.
Why Index Funds Win
1. Lower Costs
Index funds have expense ratios as low as 0.03% (that is 3 cents per year for every $100 invested). Actively managed funds often charge 1% or more—that is 33 times higher.
The math is brutal: if you invest $10,000 with a 1% fee vs. 0.03% fee, over 30 years at 7% returns, the high-fee fund costs you over $12,000 in fees alone. Same investment, $12,000 less in your pocket.
2. Most Stock Pickers Lose
Here is an uncomfortable truth: over 15-year periods, about 90% of actively managed funds fail to beat their benchmark index. The professionals, with all their research and resources, usually lose to a simple index fund.
3. No Skill Required
With an index fund, you do not need to:
- Research individual companies
- Time the market
- Follow financial news obsessively
- Wonder if you picked the right stocks
You just buy and hold.
How to Buy Index Funds
In Your : Look for funds with "Index" in the name or very low expense ratios (under 0.20%)
In an or Brokerage: Popular low-cost options:
- Vanguard (VTSAX, VTI)
- Fidelity (FZROX, FXAIX)
- Schwab (SWTSX, SWPPX)
Do This
When choosing between similar index funds, pick the one with the lowest . A fund tracking the S&P 500 from Vanguard, Fidelity, or Schwab will perform almost identically—the fees are what matter.
Common Concerns
"But what about the next Amazon?" You will own it. When a company becomes successful enough, it joins the index, and your index fund automatically buys it.
"What if the market crashes?" It will. Markets always have ups and downs. But historically, the U.S. stock market has returned about 10% annually over the long term, despite crashes, recessions, and wars.
"Is it really that simple?" Yes. Many wealthy investors, including Warren Buffett, recommend index funds for most people. Buffett has even instructed that 90% of his wife's inheritance be put in an S&P 500 index fund.
The Bottom Line
Quick Win
If you have a , log in today and check if you are invested in a low-cost index fund. If not, consider switching. This one change could save you tens of thousands of dollars over your career.
Index funds are not exciting. They will not make you rich overnight. But they are one of the most reliable ways to build wealth over time—and they require almost no effort once set up.