What does ETF mean?

An ETF (Exchange-Traded Fund) is a basket of stocks you can buy as a single ticker — SPY, for example, tracks the S&P 500's roughly 500 companies in one purchase.

An ETF (Exchange-Traded Fund) is a basket of stocks you can buy as a single ticker. SPY tracks the S&P 500 — one purchase gives you a slice of 500 companies. ETFs are popular for low-cost, instant diversification.