Four funds track the S&P 500 at near-zero cost. Their 5-year returns differ by less than 0.25%. The right one depends on where you invest.
Four mutual funds dominate the S&P 500 index space. They track the same index, own essentially the same 500 stocks, and have delivered nearly identical returns over every time period. Picking the "best" one isn't really about investment merit — it's about cost and where you invest.
Here's what the data actually shows.
| Fund | Provider | Expense Ratio | 1-Year Return | 3-Year Return | 5-Year Return | Min. Investment |
|---|---|---|---|---|---|---|
| FXAIX | Fidelity | 0.015% | 22.93% | 21.38% | 12.90% | $0 |
| FNILX | Fidelity | 0.00% | 22.64% | 21.64% | 12.72% | $0 |
| SWPPX | Schwab | 0.02% | 23.23% | 21.47% | 12.94% | $0 |
| VFIAX | Vanguard | 0.04% | 23.24% | 21.46% | 12.93% | $3,000 |
Data from CompareMutualFunds.com fund database, updated May 2026. Returns are trailing annualized figures.
The performance differences are small enough to be noise. Over five years, the spread between best and worst is 0.22 percentage points. On a $50,000 investment, that's about $110 per year — less than the cost of a tank of gas.
What actually separates these funds: fees, fund family, and availability.
Best for: Fidelity account holders who want the lowest-cost S&P 500 fund with a long track record.
FXAIX is one of the largest mutual funds in the world at $715 billion in assets. It's Fidelity's flagship S&P 500 index fund — and at 0.015%, it's among the cheapest funds of any kind available to retail investors.
FXAIX has no transaction fee at Fidelity. Buying it elsewhere may incur a commission or minimum — which effectively neutralizes the fee advantage. Use it at Fidelity.
The fund tracks the S&P 500 with minimal tracking error, holds 500+ stocks weighted by market cap, and maintains one of the lowest expense ratios of any fund on the market.
Best for: Fidelity account holders who want literally zero fees — with one important tradeoff.
FNILX is Fidelity's "ZERO" fund — 0.00% expense ratio, no minimum investment. On pure cost grounds, it wins the comparison. But there's a catch.
The catch: FNILX doesn't track the S&P 500. It tracks the Fidelity U.S. Large Cap Index — Fidelity's proprietary index, not the public S&P 500. The composition is very similar (~500 large U.S. companies), but the index is different.
This creates two practical issues:
FNILX is only available at Fidelity. It can't be held at another brokerage or transferred out in-kind. If you ever switch brokerages, you'd need to sell first — a potential taxable event.
Shorter track record. FNILX was launched more recently than the others, so there's less historical performance data.
For most Fidelity investors who plan to stay at Fidelity long-term, FNILX's 0% fee is attractive. But FXAIX's 0.015% fee is close enough that the difference is immaterial for most portfolio sizes — and FXAIX tracks the actual S&P 500, making it more portable and comparable.
The math: on $100,000, FNILX saves you $15/year versus FXAIX. That's worth it if you're certain you'll stay at Fidelity. It's not worth the portability risk if you're not.
Best for: Schwab account holders. Period.
SWPPX has the longest track record in this comparison — it's been around since 1997. It tracks the S&P 500, charges 0.02%, and has $0 minimum. From Schwab, it's free to buy and sell.
SWPPX and FXAIX have delivered nearly identical returns over every time period. The 5-year return difference: 0.04 percentage points. That's rounding error.
The expense ratio is slightly higher than FXAIX (0.02% vs 0.015%) — a $5 annual difference on $100,000. That's not a reason to choose one over the other. The real decision is: are you a Schwab customer?
Best for: Vanguard account holders, and the gold standard for long-term credibility.
VFIAX is the fund that started the index investing revolution. When Jack Bogle launched the first index fund in 1976, it eventually became what we know as VFIAX — the world's first broadly available low-cost index fund. It's now one of the largest funds in existence at $1.42 trillion in assets.
VFIAX's 0.04% expense ratio is higher than FXAIX and SWPPX — but it's still extraordinarily cheap. The difference versus FXAIX: $2.50/year per $10,000 invested.
The $3,000 minimum is the only real barrier. For investors already at Vanguard, VFIAX is the natural S&P 500 choice. For investors starting out with less than $3,000, FXAIX or SWPPX are more accessible.
The right answer depends on three factors:
This is the only decision that really matters.
| Your Brokerage | Best Fund |
|---|---|
| Fidelity | FXAIX (or FNILX if you're cost-obsessed and staying at Fidelity) |
| Schwab | SWPPX |
| Vanguard | VFIAX |
| Other | FXAIX or VFIAX (check for transaction fees first) |
Buying a fund outside its home brokerage often means paying a commission — $50+ per purchase in some cases. That transaction fee immediately wipes out years of expense ratio savings. Always buy at the home brokerage.
If not: FXAIX, SWPPX, or FNILX. All have $0 minimums.
If yes: All four options are available to you.
If yes, FNILX's 0% fee is a real (if small) long-term advantage.
If no — or if you're not sure — stick with FXAIX. It tracks the actual S&P 500, can be held or transferred anywhere, and has a 0.015% fee that rounds to zero for most investors.
Here's the uncomfortable truth about choosing between these four funds: the performance differences are so small they're essentially meaningless for long-term wealth building.
Over five years:
The total 5-year spread: 0.22 percentage points. On $100,000, that's roughly $220 per year in difference between best and worst.
Meanwhile, the decision that actually matters — how much you invest and how consistently you invest — dwarfs this completely. Investing $500/month in FXAIX starting at age 25 vs $400/month produces a difference of roughly $300,000 by retirement. The fund choice contributes far less than the contribution rate.
Pick the right fund for your brokerage. Then automate contributions, don't panic-sell during corrections, and let compounding do its work.
Before you finalize your choice, consider whether you want an S&P 500 fund at all — or whether a total market fund is better.
An S&P 500 fund holds the 500 largest U.S. companies. A total market fund (like VTSAX, FSKAX, or SWTSX) holds those same 500 companies plus thousands more mid-cap and small-cap stocks.
Over the last 20 years, total market and S&P 500 funds have performed nearly identically. The total market has slightly broader diversification. The S&P 500 applies a profitability filter (companies must have positive earnings to qualify).
For most investors, either works. If you want the broadest possible U.S. equity exposure, total market is slightly more diversified. If you want to own only large-cap leaders, S&P 500 is slightly more focused.
Both are excellent. The expense ratios are comparable.
What is the best S&P 500 index fund for 2026?
FXAIX at Fidelity, SWPPX at Schwab, and VFIAX at Vanguard are the three best-established options. All track the S&P 500, have minimal fees, and have delivered nearly identical returns for years. The "best" one is the one available at your brokerage without a transaction fee.
Is FXAIX better than VFIAX?
On expense ratio alone, yes — 0.015% vs 0.04%. Over 30 years on a $100,000 investment at 8% growth, that difference adds up to about $1,200 in FXAIX's favor. That's real but not dramatic. If you're a Vanguard investor, VFIAX is the right choice because buying FXAIX at Vanguard would incur transaction fees that wipe out the fee advantage.
Should I choose FNILX or FXAIX?
FNILX has the lower expense ratio (0.00% vs 0.015%), but it tracks a proprietary Fidelity index — not the S&P 500 — and can only be held at Fidelity. FXAIX is more portable and tracks the actual S&P 500. The cost difference is $15/year per $100,000. For most investors, FXAIX is the better default; FNILX makes sense if you're certain you'll stay at Fidelity long-term.
Do all four funds pay dividends?
Yes — all four distribute quarterly dividends from the dividends paid by the underlying S&P 500 stocks. Yields are similar: approximately 1.06%–1.18% annually. Most long-term investors set dividends to auto-reinvest.
Which has the best 10-year return?
FXAIX had the highest 10-year cumulative return at 287%, followed by SWPPX (286%) and VFIAX (281%). FNILX doesn't have a 10-year track record since it launched after 2010. These differences are small and reflect minor index construction differences rather than meaningful performance divergence.
There is no wrong answer among these four funds. They're all excellent, all essentially free, and all deliver the S&P 500's long-term returns.
The practical decision:
After that: invest consistently, increase contributions over time, and don't touch it when the market drops.
Use the CMF comparison tool to compare any two of these funds →
Data from CompareMutualFunds.com fund database, updated May 2026 via Yahoo Finance. Past performance does not guarantee future results. This article is for educational purposes only and does not constitute investment advice.
SWPPX and FXAIX both track the S&P 500 with near-zero expense ratios and $0 minimums. Their 10-year returns differ by 0.03%. The real question is which brokerage you use.
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