ITOT vs FZROX: iShares Total Market ETF or Fidelity Zero in 2026?

ITOT tracks the S&P Total Market Index and holds about 2,450 stocks. FZROX tracks Fidelity's U.S. Total Investable Market Index and holds about 2,600. Both are market-cap weighted, so their largest holdings and sector weights are nearly the same. Over the five years ending September 2026 they returned 12.58% and 12.79% a year respectively, with matching volatility.

The real difference is structure. ITOT is an ETF: it trades during the day, can be transferred to any broker in-kind, and uses in-kind redemptions that tend to minimize capital gains distributions. FZROX is a mutual fund priced once a day, which makes automatic dollar-amount investing easy but ties you to Fidelity. FZROX pays its distribution once a year in December; ITOT pays quarterly.

Because they track different indexes, some investors use ITOT and FZROX as tax-loss-harvesting partners: sell one at a loss in a taxable account and buy the other to stay invested. The IRS has never precisely defined 'substantially identical' for wash-sale purposes, so confirm the approach with a tax professional before relying on it.

For a Fidelity IRA or Roth IRA you will keep at Fidelity, FZROX saves a few dollars a year at no real cost. For a taxable account, or if you value the freedom to move brokers, ITOT is worth its 0.03%. Both are excellent core holdings; you can even buy ITOT inside a Fidelity account.