VOO vs VTI: S&P 500 or Total U.S. Market?

The Main Difference

VOO focuses on the S&P 500, so its portfolio is concentrated in large U.S. companies. VTI includes those same large companies plus thousands of smaller U.S. stocks.

Because both funds are market-cap weighted, the largest companies still dominate both portfolios. That is why their performance can often look similar even though VTI owns many more securities.

Diversification

VTI offers broader coverage of the U.S. equity market by including mid-, small- and micro-cap companies. VOO remains highly diversified across large-cap companies but does not attempt to represent the entire U.S. market.

Cost

Both funds currently report a 0.03% expense ratio, so the decision is not primarily a fee comparison. The more meaningful difference is the breadth of the underlying portfolio.

Portfolio Role

Both are commonly researched as core U.S. equity building blocks. The relevant question is whether the portfolio objective calls for S&P 500 exposure specifically or broader exposure to the full U.S. stock market.

Risk

Both remain equity funds and can experience substantial losses in market downturns. VTI adds smaller-company exposure, which can introduce additional volatility, while VOO is more concentrated in large-cap U.S. companies.