Best Index Funds 2026

What Is an Index Fund?

An index fund is a type of mutual fund or exchange-traded fund (ETF) designed to track the performance of a specific market index, such as the S&P 500, the total U.S. stock market, or the Bloomberg Aggregate Bond Index. Instead of relying on a portfolio manager to pick individual stocks, an index fund simply holds all (or a representative sample) of the securities in its target index.

This passive investment strategy was popularized by Vanguard founder John Bogle in 1976 and has since grown into one of the most widely recommended approaches for building long-term wealth. Index funds offer broad diversification, consistently low fees, and historically competitive returns compared to actively managed alternatives.

If you are new to this concept, our guide on index investing basics covers the foundational principles in detail.

How We Chose the Best Index Funds

Selecting the best index funds requires evaluating several objective criteria. Here is the methodology we used to build this list:

Expense Ratio

The expense ratio is the annual fee a fund charges as a percentage of your invested assets. Even a seemingly small difference matters: a 0.50% expense ratio versus a 0.03% expense ratio on a $100,000 portfolio compounds to thousands of dollars in lost growth over 30 years. We prioritized funds with expense ratios at or below 0.10%. For a deeper look at how fees erode returns, see our guide on investment fees explained.

Tracking Error

Tracking error measures how closely a fund replicates the returns of its target index. A well-managed index fund should have minimal deviation from its benchmark. Funds with consistently tight tracking earned higher marks in our analysis.

Fund Size (Assets Under Management)

Larger funds generally benefit from economies of scale, which can translate to lower costs and tighter bid-ask spreads. All funds on our list manage billions of dollars in assets, ensuring stability and operational efficiency.

Liquidity

For ETF versions of index funds, high daily trading volume means you can buy and sell shares without significant price impact. For mutual fund versions, we considered redemption policies and settlement times. Liquid funds allow investors to enter and exit positions smoothly.

Track Record and Provider Reputation

We focused on funds from established providers with a long history of fiduciary stewardship, including Vanguard, Fidelity, Schwab, and iShares (BlackRock). These firms have decades of experience managing index strategies and consistently act in the interest of fund shareholders.

Best Index Funds at a Glance

The table below summarizes the top index funds across U.S. equities, international equities, and bonds. Expense ratios and returns are as of the most recent reporting periods and may vary. Always verify current data before investing.

Detailed Fund Reviews

Vanguard Total Stock Market Index (VTSAX / VTI)

The Vanguard Total Stock Market Index fund is one of the most popular index funds in the world, providing exposure to the entire U.S. equity market including large-cap, mid-cap, small-cap, and micro-cap stocks. With over 3,600 holdings, it offers unmatched diversification within a single domestic equity fund.

VTSAX is the mutual fund share class with a $3,000 minimum investment, while VTI is the ETF version with no minimum beyond the cost of a single share. Both track the CRSP U.S. Total Market Index and carry an expense ratio of just 0.04%.

Pros: Extremely broad market coverage, rock-bottom fees, long track record, tax-efficient ETF option available.

Cons: The $3,000 minimum for VTSAX may be a barrier for some beginners (the VTI ETF avoids this). No international exposure, so you need a separate fund for global diversification.

Fidelity ZERO Total Market Index (FZROX)

Fidelity made headlines by launching the first zero-expense-ratio index funds, and FZROX remains the flagship of that lineup. It tracks the Fidelity U.S. Total Investable Market Index, which covers large-, mid-, and small-cap U.S. stocks. With a 0.00% expense ratio and no minimum investment, it is one of the most cost-effective ways to invest in the U.S. stock market.

Pros: Zero expense ratio, no minimum investment, no transaction fees at Fidelity, broad market exposure.

Cons: Only available through Fidelity brokerage accounts, tracks a proprietary index rather than a widely recognized benchmark, no ETF version available, relatively shorter track record compared to established Vanguard funds.

Schwab S&P 500 Index Fund (SWPPX)

SWPPX tracks the S&P 500, the benchmark of 500 of the largest U.S. companies. With an expense ratio of just 0.02% and no minimum investment, it is among the cheapest S&P 500 index funds on the market. Schwab has earned a reputation for investor-friendly policies and strong customer service.

Pros: Ultra-low expense ratio, no minimum investment, tracks the most widely followed U.S. stock index, available through Schwab with no transaction fees.

Cons: Limited to large-cap stocks (excludes mid- and small-cap), only available as a mutual fund (no ETF equivalent under this ticker), Schwab-only availability for commission-free trading.

Vanguard S&P 500 ETF (VOO)

VOO is Vanguard's ETF offering that tracks the S&P 500 index. It is one of the three largest ETFs in the world by assets under management, providing exceptional liquidity and tight bid-ask spreads. The 0.03% expense ratio makes it a fraction of a basis point more expensive than SWPPX, but the ETF structure offers added tax efficiency and flexibility.

Pros: Massive liquidity, widely available at every brokerage, excellent tax efficiency, intraday trading capability.

Cons: Cannot set up automatic dollar-amount investments as easily as a mutual fund, limited to large-cap stocks, fractional share availability depends on your broker.

iShares Core S&P 500 ETF (IVV)

Managed by BlackRock, IVV is another heavyweight S&P 500 ETF with a 0.03% expense ratio. It is virtually identical to VOO in terms of holdings and performance, with the primary difference being the fund provider. IVV is among the most traded ETFs globally, ensuring tight spreads and deep liquidity.

Pros: Extremely liquid, low expense ratio, backed by BlackRock (the world's largest asset manager), available on all major brokerages.

Cons: Nearly identical to VOO and SPY, so the choice often comes down to brokerage preference. Same large-cap-only limitation as other S&P 500 funds.

Fidelity 500 Index Fund (FXAIX)

FXAIX is Fidelity's S&P 500 index mutual fund with an industry-leading expense ratio of 0.015%, making it the cheapest S&P 500 fund on our list. There is no minimum investment requirement, and it has consistently delivered returns that tightly track the S&P 500.

Pros: Lowest expense ratio among S&P 500 funds, no minimum investment, strong tracking accuracy, easy automatic investing through Fidelity.

Cons: Mutual fund structure means end-of-day pricing only, best used within a Fidelity account for commission-free access, limited to large-cap exposure.

Vanguard Total International Stock ETF (VXUS)

VXUS provides exposure to stocks across developed and emerging markets outside the United States. With over 8,000 holdings spanning Europe, Asia-Pacific, and emerging economies, it is the most comprehensive international equity index fund available. Pairing VXUS with a total U.S. stock market fund gives investors true global diversification.

Pros: Broadest international coverage available, low 0.07% expense ratio, includes both developed and emerging markets, ideal complement to U.S. equity funds.

Cons: International markets have historically underperformed U.S. markets over the past decade, currency fluctuations add volatility, higher expense ratio compared to domestic index funds. Learn more about global diversification in our ETF investment basics guide.

Schwab Total Stock Market Index Fund (SWTSX)

SWTSX offers complete U.S. stock market exposure through Schwab's platform. Tracking the Dow Jones U.S. Total Stock Market Index, it holds thousands of stocks across all market capitalizations. The 0.03% expense ratio and $0 minimum investment make it an accessible choice for investors who prefer Schwab's brokerage services.

Pros: Very low expense ratio, total market exposure, no minimum investment, access to Schwab's research and support tools.

Cons: Mutual fund only (no ETF version under this ticker), best value within a Schwab account, slightly less well-known than Vanguard equivalents.

Vanguard Total Bond Market ETF (BND)

BND tracks the Bloomberg U.S. Aggregate Float Adjusted Index, providing exposure to the entire U.S. investment-grade bond market including treasuries, government agency bonds, mortgage-backed securities, and corporate bonds. It is the standard choice for the fixed-income portion of a diversified portfolio.

Pros: Extremely broad bond market coverage, low 0.03% expense ratio, provides ballast during stock market downturns, high liquidity.

Cons: Bond returns have been historically low in recent years, sensitive to interest rate changes, does not include high-yield or international bonds.

Fidelity Total Bond Fund (FBND)

FBND takes a slightly different approach compared to pure index bond funds. While it uses the Bloomberg U.S. Universal Bond Index as its benchmark, the fund employs some active management to seek modest outperformance. This means it may deviate slightly from its benchmark but aims to deliver better risk-adjusted returns.

Pros: Broader bond exposure than pure aggregate index funds, active management element may add value, no minimum investment at Fidelity.

Cons: Higher expense ratio (0.36%) compared to purely passive bond funds, active component introduces manager risk, performance may diverge from benchmark.

How to Invest in Index Funds

Getting started with index fund investing is straightforward. Follow these steps to begin building your portfolio:

Step 1: Define Your Investment Goals

Before selecting any fund, clarify what you are investing for. Retirement in 30 years calls for a different allocation than saving for a house down payment in five years. Your time horizon and risk tolerance will determine how much to allocate to stock index funds versus bond index funds.

Step 2: Open a Brokerage Account

You will need an account at a brokerage firm like Vanguard, Fidelity, or Schwab. Consider whether a taxable brokerage account, a traditional IRA, or a Roth IRA is most appropriate for your situation. Most brokerages offer commission-free trading on their own index funds and ETFs.

Step 3: Choose Your Funds

A simple yet effective portfolio might include just two or three index funds: a total U.S. stock market fund, a total international stock fund, and a total bond market fund. This three-fund approach covers nearly all investable public markets globally. Adjust the proportions based on your age and risk tolerance.

Step 4: Decide Between Mutual Funds and ETFs

Both structures track the same indexes, but they differ in how you buy and sell them. Mutual funds allow you to invest specific dollar amounts and set up automatic contributions easily. ETFs trade like stocks throughout the day and may offer better tax efficiency. For most long-term investors, the differences are minor.

Step 5: Invest Regularly and Stay the Course

Set up automatic contributions on a weekly, biweekly, or monthly schedule. Dollar-cost averaging into index funds removes the temptation to time the market. Once your portfolio is established, resist the urge to make frequent changes based on short-term market movements. Periodic rebalancing once or twice a year is sufficient to maintain your target allocation.

Index Fund vs ETF

The terms "index fund" and "ETF" are sometimes used interchangeably, but they refer to different things. An index fund is an investment strategy (tracking an index passively), while an ETF is a fund structure (exchange-traded). Many index funds are available as both mutual funds and ETFs. Here is how the two structures compare:

For long-term buy-and-hold investors, the choice between a mutual fund and an ETF often comes down to convenience. If you value automatic contributions in exact dollar amounts, a mutual fund may be preferable. If you want maximum tax efficiency and the ability to trade during market hours, an ETF is the better fit. In many cases, both structures track the same index and deliver nearly identical returns after fees. Our ETF investment basics guide explores these differences further.

Common Mistakes to Avoid

Index fund investing is simple in theory, but there are pitfalls that can reduce your returns or lead to poor decisions:

• Chasing past performance: The index or sector that performed best last year may not lead next year. Stick with broad, diversified funds rather than rotating into recent winners.
• Ignoring expense ratios: Even among index funds, costs vary. A 0.50% expense ratio on a fund tracking the same index as a 0.03% fund is unnecessarily expensive.
• Neglecting international diversification: U.S. stocks have outperformed in recent years, but that trend is not guaranteed to continue. International exposure helps protect against single-country risk.
• Checking your portfolio too frequently: Daily monitoring can lead to emotional decision-making. Index investing works best when you set a plan and review it periodically, not daily.
• Failing to rebalance: Over time, your portfolio drifts from its target allocation as different asset classes grow at different rates. Rebalancing once or twice per year keeps your risk level on track.
• Selling during downturns: Market declines are temporary. Selling during a downturn locks in losses and prevents you from benefiting from the eventual recovery.

Tax Considerations for Index Fund Investors

Where you hold your index funds matters for tax purposes. Consider the following strategies to minimize your tax burden:

• Use tax-advantaged accounts first: Hold index funds in IRAs, 401(k)s, or other retirement accounts where possible. Gains grow tax-deferred or tax-free.
• Place bond funds in tax-advantaged accounts: Bond interest is taxed as ordinary income, which is typically a higher rate than capital gains. Holding bond index funds in tax-sheltered accounts is generally more efficient.
• Hold equity index funds in taxable accounts: Stock index funds generate mostly long-term capital gains and qualified dividends, which are taxed at lower rates, making them more suitable for taxable brokerage accounts.
• Prefer ETFs in taxable accounts: The ETF structure is generally more tax-efficient than mutual funds due to the in-kind creation and redemption process that avoids triggering capital gains.
• Consider tax-loss harvesting: In taxable accounts, you can sell a fund at a loss and replace it with a similar (but not substantially identical) fund to realize the tax benefit while maintaining your market exposure.

Tax planning is an important component of investment returns. See our guide on investment fees for a broader view of how costs, including taxes, affect your long-term results.

Building a Complete Portfolio with Index Funds

Index funds can serve as the building blocks of a complete, diversified investment portfolio. Here are three sample portfolios based on different risk tolerances:

Aggressive Growth (Long Time Horizon)

• 70% U.S. Total Stock Market (VTSAX, FZROX, or SWTSX)
• 30% International Stock (VXUS)

This allocation is suitable for investors with 20+ years until they need the money and a high tolerance for volatility. The absence of bonds maximizes long-term growth potential but comes with larger short-term swings.

Balanced (Moderate Risk)

• 50% U.S. Total Stock Market
• 20% International Stock
• 30% Total Bond Market (BND or FBND)

A balanced approach suitable for investors with a 10-20 year horizon. The bond allocation dampens volatility while still providing meaningful equity exposure for growth.

Conservative (Near Retirement)

• 30% U.S. Total Stock Market
• 10% International Stock
• 60% Total Bond Market

Designed for investors nearing or in retirement who prioritize capital preservation and income over growth. The heavy bond weighting reduces portfolio volatility significantly.