FZROX vs VOO: Zero-Fee Total Market or S&P 500 ETF in 2026?

This is not an apples-to-apples comparison. FZROX tracks the Fidelity U.S. Total Investable Market Index and holds about 2,600 stocks of every size. VOO tracks the S&P 500, the 500 largest U.S. companies. Because both are weighted by market cap, the same mega-caps dominate both funds, but FZROX adds mid- and small-cap stocks that VOO leaves out. The closer Fidelity match for VOO is FXAIX or FNILX; the closer Vanguard match for FZROX is VTI.

Over the five years ending September 2026, VOO returned 13.77% a year and FZROX 12.79%. That gap comes from the index difference, not the fees: the largest U.S. companies outperformed smaller ones over that stretch. Over other periods smaller companies have led, so neither index wins every decade. Volatility has been nearly identical (about 16% a year for both).

FZROX has a 0.00% expense ratio and no minimum, and as a mutual fund it lets you invest exact dollar amounts automatically. VOO costs 0.03% ($30 a year per $100,000) and trades like a stock, though most brokerages now offer fractional ETF shares. The catch with FZROX is access: it is only available to Fidelity account holders, so moving to another broker means selling it.

In a Fidelity IRA or Roth IRA, FZROX is a simple, free core holding. In a taxable account, or if you might ever change brokerages, VOO's ETF structure and portability are worth the 0.03%. If what you actually want is S&P 500 exposure at Fidelity, compare FXAIX instead; if you want total-market exposure in an ETF, look at VTI or ITOT.