FZROX vs FSKAX: Is the Zero-Fee Fund Actually Better? (2026)
FZROX is Fidelity's zero-expense-ratio total market fund — it costs literally nothing to own. FSKAX charges 0.015% and tracks a standard index. Both cover the entire U.S. stock market, but there are real differences between them that matter depending on where and how you invest.
By Dan Mahler · Updated May 6, 2026
💡 Bottom Line Up Front
FZROX is the better pick if you're committed to Fidelity and investing in a Roth IRA or IRA — the 0.00% expense ratio is a genuine advantage. FSKAX wins if you invest in a taxable account or want the flexibility to move brokerages someday. Returns are nearly identical.
FZROX vs FSKAX: At a Glance
| Metric | FZROX | FSKAX |
|---|---|---|
| Expense Ratio | 0.00% | 0.015% |
| Annual Cost on $10,000 | $0.00 | $1.50 |
| Minimum Investment | $0 (both) | |
| 1-Year Return | 17.85% | 17.81% |
| 3-Year Annualized Return | 18.77% | 18.72% |
| 5-Year Annualized Return | 11.49% | 11.28% |
| Total Assets (AUM) | $32B | $119B |
| Inception Date | August 2018 | September 2011 |
| Index Tracked | Fidelity U.S. Total Investable Market (proprietary) | Dow Jones U.S. Total Stock Market |
| Portable to Other Brokerages? | No | Yes |
| Correlation | 0.99+ (near-identical) | |
Performance: Does FZROX Actually Beat FSKAX?
Surprisingly, yes — but only barely. FZROX has edged out FSKAX in every measured period, likely because paying 0.00% in fees vs 0.015% compounds slightly in FZROX's favor over time. The margin is too small to matter in practice — both funds deliver essentially the same market return.
| Time Period | FZROX | FSKAX | Difference |
|---|---|---|---|
| 1-Year Return | 17.85% | 17.81% | +0.04% |
| 3-Year Annualized | 18.77% | 18.72% | +0.05% |
| 5-Year Annualized | 11.49% | 11.28% | +0.21% |
Data from CMF fund database, updated May 2026. FZROX launched in August 2018, so long-term history beyond 5 years is limited compared to FSKAX (inception 2011).
The 0.00% Expense Ratio: How Much Does It Actually Matter?
FZROX charges nothing. FSKAX charges 0.015% — or $1.50 per year on a $10,000 investment. On paper, FZROX wins. But let's run the numbers over 30 years:
| Portfolio Size | Annual Fee — FZROX (0.00%) | Annual Fee — FSKAX (0.015%) | Annual Savings with FZROX |
|---|---|---|---|
| $10,000 | $0.00 | $1.50 | $1.50 |
| $100,000 | $0.00 | $15.00 | $15.00 |
| $500,000 | $0.00 | $75.00 | $75.00 |
| $1,000,000 | $0.00 | $150.00 | $150.00 |
The fee difference is real but small. On a $500,000 retirement portfolio, FZROX saves you $75/year compared to FSKAX. Over 30 years with compounding, that adds up — but the portability tradeoff matters more for most investors.
FZROX's Major Catch: You Can't Leave Fidelity
FZROX tracks a proprietary Fidelity index — the Fidelity U.S. Total Investable Market Index — which means it cannot be transferred in-kind to another brokerage. If you ever move from Fidelity to Vanguard, Schwab, or anywhere else, you would need to sell your FZROX shares before transferring.
In a tax-advantaged account (Roth IRA, traditional IRA), selling and rebuying is generally painless — no capital gains taxes, and you can immediately reinvest in a comparable fund at the new brokerage. The portability limitation mostly doesn't matter in IRAs.
In a taxable brokerage account, this is a real risk. If FZROX has appreciated significantly, selling to move brokerages triggers a taxable event. FSKAX, which tracks the standard Dow Jones index, can be transferred in-kind to virtually any major brokerage without selling.
FZROX's Proprietary Index: Does It Matter?
FZROX tracks the Fidelity U.S. Total Investable Market Index, which Fidelity controls. FSKAX tracks the Dow Jones U.S. Total Stock Market Index, an independent standard benchmark.
In practice, this hasn't mattered — both indexes hold roughly the same stocks weighted roughly the same way, and the correlation is above 0.99. The theoretical risk of a proprietary index is that Fidelity could change the methodology, though there's no evidence they've done so or plan to.
FZROX also holds approximately 2,700 stocks vs FSKAX's ~3,900. The ~1,200 additional stocks in FSKAX are micro-cap companies that collectively represent less than 1% of fund value — this difference is negligible in terms of real-world diversification.
FZROX vs FSKAX: Which Should You Choose?
Choose FZROX if you…
- ✅ Are committed to staying at Fidelity long-term
- ✅ Investing in a Roth IRA, traditional IRA, or 401(k)
- ✅ Want to pay absolutely nothing in fund fees
- ✅ Are a beginner who wants the simplest, cheapest option
Choose FSKAX if you…
- ✅ Invest in a taxable brokerage account
- ✅ Might switch brokerages in the future
- ✅ Prefer a standard, widely-tracked index
- ✅ Want broader market coverage (~3,900 stocks)
Our Verdict
If you have a Fidelity IRA and plan to stay, pick FZROX — it's the obvious choice. The zero fee is real, returns are nearly identical (FZROX actually edges FSKAX), and the portability limitation doesn't matter inside an IRA. If you invest in a taxable account or value flexibility, FSKAX is the safer, more versatile fund. At 0.015%, the cost is still extremely low.
Frequently Asked Questions
Is FZROX better than FSKAX?
FZROX has a slight edge in recent returns and charges 0.00% vs FSKAX's 0.015%. However, FZROX is Fidelity-exclusive — you cannot transfer it to another brokerage. FSKAX is better if you want flexibility or invest in a taxable account. FZROX is better if you're committed to Fidelity and investing in a Roth IRA.
What is the difference between FZROX and FSKAX?
FZROX is Fidelity's zero-fee total market fund (0.00% expense ratio) that tracks a proprietary Fidelity index. FSKAX charges 0.015% and tracks the standard Dow Jones U.S. Total Stock Market Index. FZROX can only be held at Fidelity; FSKAX is portable to other brokerages.
Does FZROX outperform FSKAX?
FZROX has slightly outperformed FSKAX — 17.85% vs 17.81% over 1 year, and 11.49% vs 11.28% over 5 years. These differences are negligible in practice. Both funds track the same broad U.S. market.
Can I hold FZROX in a Roth IRA?
Yes. FZROX is available in Fidelity Roth IRAs, traditional IRAs, and 401(k)s. It's a strong choice for tax-advantaged accounts because the portability limitation matters less when you're not planning to transfer the account.
Why is FZROX so much smaller than FSKAX?
FZROX launched in 2018 vs FSKAX's 2011 launch. FSKAX has had more time to accumulate assets ($119B vs $32B). FZROX is also Fidelity-exclusive, limiting its audience. Both are well-managed funds.
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