FNILX vs FXAIX: Comparing Fidelity’s U.S. Large-Cap Funds
This article compares FNILX vs FXAIX — Fidelity’s ZERO® Large Cap Index Fund vs Fidelity’s S&P 500 Index Mutual Fund.
Both are passively managed index mutual funds popular in retirement accounts for investors seeking near-market returns vs risk-free high-yield savings.
Index mutual funds track market indexes, such as the S&P 500.
FXAIX tracks the S&P 500, while FNILX tracks a similar custom index of the largest U.S. 500 stocks, which is not identical because the S&P 500 has profitability requirements for inclusion and the FNILX benchmark does not.
You own a tiny piece of the largest U.S. companies if you own either fund.
Passive index fund managers do not pick stocks. They allocate money to all stocks in the market index to track its performance and take a small fee to achieve this outcome.
Since most actively managed mutual funds do not beat their target benchmarks, many fiduciary financial planners recommend index funds instead of actively managed funds or individual stocks.
Table of Contents
Bottom Line Upfront (BLUF)
Before I get into the details of FNILX vs FXAIX, it’s important to keep the following in mind:
- Both funds are excellent, low-fee options with similar returns. Don’t overthink your choice.
- FXAIX is tied to the S&P 500 index, whereas FNILX is indexed to the 500 largest U.S. companies by market cap. Fast-growing but unprofitable companies will not be included in FXAIX but may be in FNILX.
- FNILX is marketed as a no-expense fund. FXAIX has a very small expense ratio. The difference is insignificant.
- FNILX tends to pay a lower dividend, thus reducing the tax burden if you own this in a taxable account.
- Investors who do not have a Fidelity account can invest in ETF equivalents (see Equivalents section).
Please note that both funds update their prospectuses regularly, and the information in this article will change over time.
Fidelity’s website is the best resource for both funds.
Here are links to the most updated information at Fidelity. Consider the information on those pages to be the authoritative data source.
- Fidelity ZERO® Large Cap Index Fund (FNILX)
- S&P 500 Index Mutual Fund (FXAIX)
FNILX vs FXAIX Comparison
Side-by-Side
Here’s a side-by-side comparison of both funds. Scroll right on mobile.
A few noticeable differences comparing FNILX vs FXAIX:
- The benchmark indexes are different.
- FNILX is a zero-expense ratio fund. This is more of a marketing strategy than a meaningful comparison data point.
- FXAIX is a much older and larger fund. The yield percentage is considerably higher.
Overlap
These funds are similar but not identical. FNILX invests in the 500+ largest-cap U.S. stocks, while FXAIX invests to match the performance of the S&P 500.
That may sound the same, but the S&P 500 index has profitability requirements that companies must meet to be included. In contrast, FNILX only considers the largest market-cap indexes.
So, a large and growing company that is unprofitable may be included in FNILX but not FXAIX.
FNILX is also float-adjusted, which means the index is tied to only the floated shares (available to invest in public markets), not the total outstanding shares.
However, there is still a significant overlap between the funds, estimated to be 95%-99%.
Benchmark Indexes
FNILX is indexed to the Fidelity U.S. Large Cap Index TR. This is a custom index requested by Fidelity and maintained by SG Global.
The Fidelity U.S. Large Cap Index TR is a float-adjusted market capitalization-weighted index designed to reflect the performance of the U.S. equity market, including large-capitalization stocks.
FXAIX is indexed to the S&P 500 owned by SP Global.
Visit this page to find a Fact Sheet and Methodology documentation with the latest information on that page.
The index also has about 500 constituents, comprising the largest companies traded in U.S. markets.
Performance Chart
Here’s a daily updated FNILX vs FXAIX chart tracking against each other since FNILX’s inception date. Scroll right on mobile.
Due to their significant overlap, these funds perform mostly in unison. Therefore, either one is suitable for broad equity coverage in your portfolio.
See the table above for three and five-year average annual performance records.
This chart updates daily and does not account for dividend distributions. Hover over the lines for prices.
Top Ten Holdings
Here are the top ten holdings for each fund. For the most updated lists, visit the links at the beginning of the article.
FNILX
As of 02/01/2025 | |||
---|---|---|---|
# | Symbol | Company | Weight |
1 | AAPL | APPLE INC | 0.06965 |
2 | MSFT | MICROSOFT CORP | 0.05984 |
3 | NVDA | NVIDIA CORP | 0.0593 |
4 | AMZN | AMAZON COM INC | 0.04258 |
5 | META | META PLATFORMS INC CLASS A | 0.02904 |
6 | GOOGL | ALPHABET INC CLASS A | 0.02276 |
7 | TSLA | TESLA INC | 0.02168 |
8 | AVGO | BROADCOM INC | 0.01953 |
9 | GOOG | ALPHABET INC CLASS C | 0.0187 |
10 | BRK-B | BERKSHIRE HATHAWAY INC CLASS B | 0.01679 |
FXAIX
As of 02/01/2025 | |||
---|---|---|---|
# | Symbol | Company | Weight |
1 | AAPL | Apple Inc. | 0.07604 |
2 | NVDA | NVIDIA Corp. | 0.06617 |
3 | MSFT | Microsoft Corp. | 0.06295 |
4 | AMZN | Amazon.com Inc. | 0.04124 |
5 | META | Facebook Inc. Class A | 0.02564 |
6 | TSLA | Tesla Inc. | 0.02265 |
7 | GOOGL | Alphabet Inc. Class A | 0.02222 |
8 | AVGO | Broadcom Inc. | 0.02175 |
9 | GOOG | Alphabet Inc. Class C | 0.01821 |
10 | BRK-B | Berkshire Hathaway Inc. Class B | 0.01669 |
Fund Equivalents
- The FNILX Vanguard equivalent (near) is VFIAX
- The FXAIX Vanguard equivalent is VFIAX.
- The FNILX Vanguard ETF equivalent (near) is VOO.
- The FXAIX Vanguard ETF equivalent is VOO.
Exchange-traded funds (ETFs) trade like stocks. You can buy or sell them during the day on a stock exchange.
ETFs are easier to own, and their price changes throughout the day. Mutual funds only trade at the market close.
Active investors typically use ETFs for trading purposes or to buy and hold indexes when they can’t access index mutual funds.
For example, if you have an investing account with a popular discount broker, you’d invest via ETFs instead of mutual funds. If your account is with Fidelity or Vanguard, you’d likely use the index funds FNILX vs FXAIX.
The FNILX iShares equivalent (near) is the iShares Core S&P Total U.S. Stock Market ETF(symbol: SPY), which is a good ETF with a higher expense ratio (about 0.09%). You can buy the SPY through any online broker.
Best Brokers to Own Index Funds and ETFs
What is the best broker for market index ETFs if not Fidelity or Vanguard?
Fidelity and Vanguard are excellent choices for long-term retirement investors. You’re in good hands if your IRA or employer-sponsored plan is with either broker.
Check out my list of best online brokers to find the best fit for you.
Conclusion
If you’re struggling to decide between FNILX vs FXAIX you’re splitting hairs. Both are fine. The zero-fee aspect of FNILX is more of a marketing ploy than meaningful advantage compared to FXAIX, which has a 0.015% expense ratio.
FNILX may have a slight edge because of its lower expense ratio and exposure to fast-growing companies that are not profitable yet (e.g., Amazon and Tesla were large companies before being part of the S&P 500 because they operated at a loss).
Those with a Fidelity account can own FNILX or FXAIX. Vanguard account holders can use VFIAX. Consider ETF equivalents like VOO or IVV if you are with another broker.
Companies that become part of the S&P 500 are some of the most successful in the world.
FXAIX is somewhat more strict with its company inclusion than FNILX, and therefore, fast-growing companies that aren’t yet profitable could contribute high returns to FNILX.
ETFs like IVV and VOO will give you the same or similar coverage, performance, and low cost at any commission-free online broker.
Please reply with your questions regarding FNILX vs FXAIX in the comments section below. Include any requests you have about adding more detail to this article.
Additional Resources
Disclosure: The author owns FNILX, FXAIX, and FSKAX.
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