ETFs and index funds, without the jargon

An ETF (exchange-traded fund) is a basket of securities that trades like one stock. An index fund follows a published list, such as the S&P 500, a list of about 500 large US companies, instead of a manager's picks. Many of the largest ETFs are index funds.

What you own inside the common ones

Fund	What it holds	Expense ratio
VOO	About 500 large US companies (S&P 500)	0.03%
VTI	The whole US market, large to small, thousands of stocks	0.03%
QQQ	The 100 largest non-financial companies listed on the Nasdaq, tech heavy	0.18%
SCHD	About 100 US dividend payers screened for quality	0.06%

Expense ratios as published by each fund sponsor. QQQ's fee fell from 0.20% to 0.18% when it converted to a standard ETF in December 2025. Fees change occasionally, so check the fund page.

Reading an expense ratio

It is the yearly fee as a share of your balance, taken out inside the fund so you never see a bill. On $10,000, 0.03% is $3 a year. A 1% fund costs $100 a year on the same balance. Over 20 years the gap compounds. The chart above shows $10,000 growing 8% a year before fees: the 1% fund ends about $7,700 behind the 0.03% fund.

How you buy one

An ETF trades all through the regular session, 9:30 AM to 4:00 PM ET, at whatever price buyers and sellers agree on, just like a stock. An index mutual fund, the older cousin, fills once a day at a price set after the 4:00 PM ET close. For the big, heavily traded ETFs the spread, the gap between the buy and sell price, is usually a penny or two. A limit order still lets you set the most you will pay. Many brokers also sell fractional shares, so a fund priced at $500 a share can be bought with $50. The wrapper matters less than two things: what the fund holds and what it charges.

Overlap is the hidden risk

Owning VOO, QQQ and a tech ETF feels diversified, meaning spread out. It is not. The same handful of mega-cap companies, the largest by market value, sit at the top of all three. Before adding a fund, look at its top ten holdings and ask whether you already own them.

How they fit the other clocks

Index funds are the long-term core. SPY, QQQ and IWM are also among the most heavily traded funds in the world, which is why the desk uses them for day trades and hedges. A hedge is a position meant to gain when your main holdings fall. Same ticker, different clock, different account.

Try this

Pick two funds you own or are curious about. On each fund's website, find the top ten holdings and count how many names appear on both lists. Then find each expense ratio and work out the yearly cost on $10,000. Write both numbers down.