Wealthy PotFNILX vs FZROX: Both Free, and 90% of FZROX Is Already FNILX
FNILX and FZROX are Fidelity's two free US stock index funds, and they differ by one thing: the companies below the largest 500. FNILX holds roughly the 500 largest US companies. FZROX holds those same companies plus about 2,100 mid and small caps. Both charge a 0.00% expense ratio. Matching their SEC holdings filings for 31 July 2026, all 501 FNILX holdings were inside FZROX and the overlap was 90.0%. The extra 2,105 positions made up 9.8% of FZROX. Both funds come with the same restriction: Fidelity sells them only to retail investors buying through a Fidelity brokerage account. Pick one. Owning both is mostly owning the same 500 stocks twice.
Table of Contents
The Short Answer
- Fees: 0.00% and 0.00%. Both prospectuses show a 0.00% management fee, 0.00% other expenses, and a $0 cost on $10,000 at every horizon. Fidelity's annual report confirms both funds paid a total advisory fee of $0.
- Overlap: 90.0%. 99.7% of FNILX's money sat in stocks FZROX also held (the rest was cash). 90.0% of FZROX's money sat in FNILX stocks. Our calculation from both funds' 31 July 2026 N-PORT filings.
- Holdings: 501 vs 2,606 in those filings.
- Top ten: 38.4% vs 34.7%. FZROX is slightly less top-heavy.
- Returns to 30 September 2026: FNILX ahead over 3 and 5 years (13.49% vs 12.80% a year over five), FZROX ahead over 1 year (15.41% vs 15.25%).
- Same indexes family. Both track Fidelity's own indexes: FNILX the Fidelity U.S. Large Cap Index, FZROX the Fidelity U.S. Total Investable Market Index. The large-cap index is a subset of the total market one.
- Same restriction. Both are "available only to individual retail investors who purchase their shares through a Fidelity® brokerage account," per their prospectuses.
How Much of FZROX Is Already FNILX
Fidelity's own prospectus explains why these two overlap so heavily. The Fidelity U.S. Large Cap Index "is a subset of the Fidelity U.S. Total Investable Market Index," and large caps are "considered to be stocks of the largest 500 U.S. companies based on float-adjusted market capitalization." FNILX holds the top of FZROX's index. The filings show how big that top is.
| Portfolios at 31 July 2026 | FNILX | FZROX |
|---|---|---|
| Holdings in the filing | 501 | 2,606 |
| Held by both funds | 501 | 501 |
| Share of the fund in those shared holdings | 99.7% | 90.0% |
| Holdings the other fund did not own | 0 | 2,105 (9.8% of FZROX) |
| Overlap, sum of the smaller weight in each shared stock | 90.0% | |
The 2,105 extra companies average under 0.005% each. Together they are 9.8% of FZROX. The largest of them was about 0.06% of the fund. That is the honest size of "total market" versus "large cap": about one dollar in ten.
The large caps also sit at slightly lower weights inside FZROX, because that tenth of the fund has to come from somewhere. NVIDIA was 7.43% of FNILX and 6.71% of FZROX; Apple 6.93% against 6.26%; Microsoft 5.27% against 4.76%. The top ten were 38.44% of FNILX and 34.70% of FZROX, both measured from the same 31 July 2026 filings.
FNILX vs FZROX Side by Side
| FNILX | FZROX | |
|---|---|---|
| Full name | Fidelity ZERO Large Cap Index Fund | Fidelity ZERO Total Market Index Fund |
| Index | Fidelity U.S. Large Cap Index (largest 500 US companies) | Fidelity U.S. Total Investable Market Index (large, mid and small caps) |
| Index provider | Fidelity Product Services LLC, a Fidelity affiliate | Fidelity Product Services LLC |
| Expense ratio | 0.00% | 0.00% |
| Holdings (31 Jul 2026 filing) | 501 | 2,606 |
| Top-10 weight (31 Jul 2026) | 38.4% | 34.7% |
| Fund size (31 Oct 2025) | $15.8 billion | $31.8 billion |
| Information technology (31 Oct 2025) | 36.4% | 34.2% |
| Industrials (31 Oct 2025) | 8.1% | 9.5% |
| Portfolio turnover, FY to 31 Oct 2025 | 3% | 3% |
| Method | Statistical sampling | Statistical sampling |
| Fund type | Mutual fund, traded once a day at NAV | Mutual fund, traded once a day at NAV |
| Purchase minimum | None | None |
| Inception | 13 Sep 2018 | 2 Aug 2018 |
Is the 0.00% real? Yes, on the audited numbers. Neither fee table carries a waiver footnote, and the annual report for the year to 31 October 2025 shows "Total Advisory Fee $0" for both funds and a cost of under 50 cents on a $10,000 investment. FNILX's statutory prospectus explains the arrangement: the funds pay no management fee, and "Fidelity compensates the Adviser for the services it provides to the funds."
Returns: Large Caps vs the Whole Market
Neither fund is ten years old, so there is no ten-year figure. Both Fidelity pages report the same date, which makes the comparison clean.
| Average annual return to 30 Sep 2026 | 1 year | 3 years | 5 years | Since inception |
|---|---|---|---|---|
| FNILX | 15.25% | 23.02% | 13.49% | 14.61% (from 13 Sep 2018) |
| Fidelity U.S. Large Cap Index | 15.25 | 23.00 | 13.49 | 14.59 |
| FZROX | 15.41% | 22.45% | 12.80% | 14.11% (from 2 Aug 2018) |
| Fidelity U.S. Total Investable Market Index | 15.43 | 22.43 | 12.77 | 14.10 |
| FNILX minus FZROX | -0.16 | +0.57 | +0.69 | not comparable |
Each fund matched its own index to within about 0.03 points a year, so the gap between them is the gap between large caps and the whole market. Over three and five years the largest 500 companies led. Over the latest year the mid and small caps pulled FZROX slightly ahead. Fidelity's annual report to 31 October 2025, a different window, had FNILX ahead over one year (22.01% vs 20.98%) and five years (17.42% vs 16.88%).
| Hypothetical $10,000 held 5 years | Ending value |
|---|---|
| At FZROX's 5-year return (12.80%) | $18,262 |
| At FNILX's 5-year return (13.49%) | $18,827 |
Taxes. The prospectuses print after-tax returns for the five years to 31 December 2024: FNILX lost 0.33 points a year to taxes on distributions (14.62% before, 14.29% after), FZROX 0.38 points (13.93% before, 13.55% after). Close enough that it should not drive the choice. Both are mutual funds rather than ETFs, so neither trades on an exchange.
This is educational information, not personalized investment advice. Past performance does not guarantee future results, and all investing carries the risk of loss.
The Fidelity-Only Rule Both Share
This is not a point of difference between FNILX and FZROX, because the rule is word for word the same in both prospectuses. It matters for whether you should use either one:
"Shares of the fund are available only to individual retail investors who purchase their shares through a Fidelity® brokerage account, including retail non-retirement accounts, retail retirement accounts (traditional, Roth and SEP Individual Retirement Accounts (IRAs)), health savings accounts (HSAs), Fidelity BrokerageLink® accounts, and stock plan services accounts. Shares also may be available to certain broker-dealers that have entered into arrangements with Fidelity."
Two practical consequences follow, and we want to be precise about which part is Fidelity's wording and which is ours.
- Fidelity's wording: you can buy these funds in a Fidelity brokerage account, IRA, HSA, BrokerageLink or stock plan account. There is no purchase minimum. Fidelity also reserves the right to impose a "purchase maximum" if a shareholder's purchases or balance exceed a threshold, without naming a figure.
- Our inference: because shares are offered only through Fidelity accounts, apart from broker-dealers with arrangements with Fidelity, most other brokers are unlikely to accept them. If you ever move your account away from Fidelity, expect to sell them first. In a taxable account that sale can realize a capital gain. The prospectus does not use the phrase "cannot be transferred in kind", and we do not attribute it to Fidelity. Ask the receiving broker before you plan a move.
In an IRA or HSA, selling inside the account has no tax cost, so the restriction matters much less. In a taxable account it is a real reason to consider Fidelity's conventional index funds, FXAIX and FSKAX, which each charge 0.015% per their April 2026 summary prospectuses: see FZROX vs FXAIX and FSKAX vs FZROX.
Which One Fits You
If you want one US stock fund in a Fidelity IRA, Roth IRA or HSA, FZROX is the simpler single holding. It owns the whole market, so you never have to decide whether small and mid caps belong in your portfolio. It costs nothing, and the Fidelity-only restriction has no tax cost inside a retirement account.
If you want large caps only, or you hold a separate small-cap or extended-market fund, FNILX. It is effectively Fidelity's free version of an S&P 500 fund, though it tracks Fidelity's own index rather than the S&P 500; FNILX vs FXAIX and FNILX vs VOO cover that difference. Pairing FNILX with Fidelity's ZERO Extended Market fund lets you set your own small-cap weight instead of taking the market's.
Do not hold both expecting diversification. Every FNILX stock is inside FZROX. Holding both gives you about 90% duplication and a slight tilt back to large caps.
In a taxable Fidelity account, both carry the move-brokers caveat above. If you are confident you will stay at Fidelity, the zero fee is fine. If not, the conventional funds cost $1.50 a year per $10,000 and avoid the issue.
Not at Fidelity? Neither fund is for you. The ETF equivalents are an S&P 500 fund such as VOO or a total-market fund such as VTI; see FZROX vs VTI.
Sources & Methodology
- FNILX summary prospectus, 30 December 2025 and FZROX summary prospectus, 30 December 2025: fee tables, index descriptions, the purchase and eligibility language, and after-tax returns to 31 December 2024.
- Fidelity Concord Street Trust Form N-CSR, year ended 31 October 2025: costs paid, advisory fees, fund size, holdings counts, sectors and returns.
- FNILX Form N-PORT, 31 July 2026 and FZROX Form N-PORT, 31 July 2026: holdings behind the overlap and concentration figures.
- Fidelity FNILX performance page and Fidelity FZROX performance page: average annual returns to 30 September 2026.
How the overlap was computed. For each stock both funds held we took the smaller of its two weights and summed them, the same method and N-PORT data the Portfolio Overlap Checker uses. Both filings are dated 31 July 2026.
What we could not verify. Whether a specific outside broker will accept ZERO fund shares in a transfer is not stated in any Fidelity filing we read, so we describe the eligibility rule and leave the transfer outcome as an inference. The prospectus gives no dollar threshold for the possible purchase maximum.
This article is for general education and is not investment, tax or legal advice. Past performance does not guarantee future results, and all investing carries the risk of loss. Figures were checked against the sources above on 4 October 2026; confirm current details with Fidelity before acting.
FAQ: FNILX vs FZROX
Is FNILX or FZROX better?
Neither by cost: both charge 0.00%. FZROX owns the whole US market and FNILX the largest 500 companies, which are 90% of FZROX anyway. FNILX returned 13.49% a year over the five years to 30 September 2026 against 12.80% for FZROX; FZROX was ahead over the latest year. Choose FZROX for one-fund simplicity, FNILX if you want large caps only.
How much do FNILX and FZROX overlap?
90.0% by weight in their 31 July 2026 SEC filings. All 501 FNILX holdings were in FZROX. The 2,105 stocks only FZROX held were 9.8% of that fund.
Should I hold both FNILX and FZROX?
There is little reason to. Holding both duplicates about 90% of the portfolio and slightly overweights large caps. Choose one, or pair FNILX with a dedicated small and mid-cap fund if you want to control that weight yourself.
Are FNILX and FZROX really free?
Yes. Both prospectuses list total annual operating expenses of 0.00% with no waiver footnote, and the audited annual report shows a $0 advisory fee for both funds in the year to 31 October 2025.
Do FNILX and FZROX track the S&P 500 or a Dow Jones index?
Neither. Both track indexes created by Fidelity Product Services LLC: the Fidelity U.S. Large Cap Index for FNILX and the Fidelity U.S. Total Investable Market Index for FZROX.
Can I buy FNILX or FZROX outside Fidelity?
Generally no. Both prospectuses say shares are "available only to individual retail investors who purchase their shares through a Fidelity® brokerage account," with an exception for certain broker-dealers that have arrangements with Fidelity.
What happens if I leave Fidelity?
The prospectus does not address account transfers directly. Because the funds are offered only through Fidelity accounts, expect to sell before moving, which can trigger capital gains tax in a taxable account but not inside an IRA or HSA. Ask the receiving broker first.
Is there a minimum investment?
No. Both prospectuses say "There is no purchase minimum for fund shares."
Cite This Page
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"FNILX vs FZROX: Both Free, and 90% of FZROX Is Already FNILX." Wealthy Pot, 2026. https://wealthypot.com/fnilx-vs-fzrox/
Related comparisons: FZROX vs FXAIX · FNILX vs FXAIX · FSKAX vs FZROX · FNILX vs VOO · FZROX vs VTI · All ETF comparisons
