Fidelity is one of the largest asset managers in the U.S. and a major player in low-cost index investing. Many investors choose Fidelity index funds for their broad market exposure, competitive expense ratios and accessibility, especially for retirement and long-term investing.
While Fidelity offers dozens of index-based funds, the best choice depends on how the fund fits into your portfolio. Some are designed as core holdings that track entire markets, while others provide targeted exposure to stocks, bonds or international equities.
At a Glance: Best Fidelity Index Funds
Fund Ticker Primary Exposure Risk Profile / Use Case One-Line Reason It Stands Out Fidelity ZERO Total Market Index Fund FZROX U.S. stock market Medium Zero expense ratio Fidelity Total Market Index Fund FSKAX U.S. stock market Medium Broad exposure with long track record Fidelity 500 Index Fund FXAIX Large-cap U.S. stocks Medium Tracks the S&P 500 at low cost Fidelity Extended Market Index Fund FSMAX Mid- and small-cap U.S. stocks Medium to high Complements S&P 500 funds Fidelity International Index Fund FSPSX International developed markets Medium Global diversification Fidelity U.S. Bond Index Fund FXNAX Investment-grade U.S. bonds Low to medium Core bond diversification Fund objectives and expenses are based on current Fidelity disclosures.
Why Investors Choose Fidelity Index Funds
Index funds aim to match market performance rather than outperform it, which helps keep costs low. According to Fidelity, lower expense ratios can significantly improve long-term investment outcomes through compounding.
The U.S. Securities and Exchange Commission also notes that fund fees are one of the most reliable predictors of long-term returns.
What Is a Fidelity Index Fund?
A Fidelity index fund is a mutual fund that tracks a specific market index, such as the S&P 500 or the total U.S. stock market. These funds are passively managed and designed to deliver returns closely aligned with their benchmark.
According to the Investment Company Institute, index mutual funds remain a popular choice for long-term investors due to transparency and diversification.
Best Fidelity Index Funds To Consider
Fidelity ZERO Total Market Index Fund (FZROX)
FZROX tracks the total U.S. stock market and carries a zero expense ratio. Fidelity disclosures note that the fund is available only to Fidelity account holders. Performance closely follows broad market movements.
Fidelity Total Market Index Fund (FSKAX)
FSKAX provides exposure to large-, mid- and small-cap U.S. stocks. According to Fidelity, it is commonly used as a core equity holding. Its long operating history appeals to investors who value consistency.
Fidelity 500 Index Fund (FXAIX)
FXAIX tracks the S&P 500 Index and focuses on large-cap U.S. companies. Fidelity reports that the fund is widely used in retirement accounts due to its low expense ratio. It is less diversified than total market funds.
Fidelity Extended Market Index Fund (FSMAX)
FSMAX covers U.S. stocks not included in the S&P 500, primarily mid- and small-cap companies. Fidelity disclosures highlight its role as a complement to large-cap funds. Smaller-cap exposure increases volatility.
Fidelity International Index Fund (FSPSX)
FSPSX invests in developed international markets outside the U.S. According to Fidelity, international exposure can reduce reliance on domestic economic conditions. Currency fluctuations can affect returns.
Fidelity U.S. Bond Index Fund (FXNAX)
FXNAX tracks the Bloomberg U.S. Aggregate Bond Index, offering exposure to Treasurys, corporate bonds and mortgage-backed securities. Fidelity notes that it is often used to balance stock risk. Interest-rate sensitivity remains a consideration.
Fidelity Index Funds vs. Fidelity ETFs
| Feature | Fidelity Index Funds | Fidelity ETFs |
|---|---|---|
| Trading | Once per day at NAV | Intraday |
| Minimum Investment | Often none | None |
| Expense Ratios | Very low | Very low |
| Tax Efficiency | Moderate | Higher |
| Automation | Easy | Limited |
The Investment Company Institute notes that ETFs tend to be more tax-efficient, while mutual funds are often easier for automatic investing.
Risks To Understand Before Investing
Even diversified index funds carry market risk. The SEC cautions that index funds fully reflect market downturns and do not provide downside protection.
Bond index funds are also sensitive to changes in interest rates.
How Fidelity Index Funds Fit Into a Portfolio
Many investors use Fidelity index funds as core building blocks, combining U.S. stocks, international stocks and bonds. Fidelity research shows that asset allocation has a greater impact on returns than individual fund selection.
Index funds are commonly used in retirement accounts such as IRAs and 401(k)s.
Final Take to GO
Fidelity index funds offer low-cost, diversified access to major asset classes. Funds like FZROX and FXAIX work well as core equity holdings, while FXNAX provides bond exposure for balance. For most investors, Fidelity index funds are most effective when combined into a diversified, long-term investment strategy.
Best Fidelity Index Funds FAQ
- What is the best Fidelity index fund?
- The best Fidelity index fund depends on your investment goals, risk tolerance and time horizon.
- Are Fidelity index funds good for beginners?
- Yes, many Fidelity index funds offer broad diversification and low costs suitable for beginners.
- Do Fidelity index funds have minimum investments?
- Many Fidelity index funds have no minimum investment requirement.
- Are Fidelity ZERO funds really free?
- They have zero expense ratios but are available only through Fidelity accounts.
- How are Fidelity index fund returns taxed?
- Taxes depend on account type and whether distributions are dividends or capital gains.
Daria Uhlig and John Csiszar contributed to the reporting for this article.
Data is accurate as of Jan. 29, 2026, and is subject to change. Data was sourced from Fidelity and Yahoo! Finance.
Editorial Note: This content is not provided by any entity covered in this article. Any opinions, analyses, reviews, ratings or recommendations expressed in this article are those of the author alone and have not been reviewed, approved or otherwise endorsed by any entity named in this article.