SPY and VOO both target the S&P 500. VTI targets the total U.S. stock market, which still leans heavily on large caps but also includes mid- and small-cap stocks. Investors often treat them as interchangeable; historically they are close, not identical.
SPY vs VOO
Same index family, different issuers, fees, and structures. Over long stretches the wealth paths usually hug each other. A side-by-side $10,000 chart is the fastest way to see how small those gaps have been for your dates.
Adding VTI
VTI’s extra mid/small-cap exposure can lead or lag the S&P 500 depending on the cycle. When large mega-caps dominate, SPY/VOO and VTI often look similar; when smaller stocks run, VTI can pull ahead — and the reverse in other regimes.
Run SPY, VOO, and VTI together below. Keep DRIP on for a total-return view.