Best Index Funds for Long-Term Investors: March 2026
Six low-cost funds covering U.S. stocks, international stocks, and bonds — the building blocks of any evidence-based portfolio.
Rates and picks as of March 2026. Rates change often — confirm current terms with each provider before applying.
Important: The items below are funds, not accounts. You need a brokerage account (Fidelity, Vanguard, Schwab, or any other) to hold them. If you don't have one yet, see our guide to the best brokerages for beginners.
The six funds below cover the entire investable world — U.S. stocks, international stocks, and bonds — at expense ratios between 0.00% and 0.08% as of March 2026. On a $50,000 portfolio, even the most expensive fund here costs $40/year. Active funds charging 0.75%–1.5% cost $375–$750 for the same balance. Over 30 years, that difference compounds to tens of thousands of dollars.
| Fund | Expense Ratio | Asset Class | Min. Investment | |
|---|---|---|---|---|
FZROX·Fidelity ZERO Total Market Index FundBest Overall Fidelity Investments | 0.00% | U.S. Total Market | $0 | View on Fidelity |
VTI·Vanguard Total Stock Market ETFBest for Portability Vanguard | 0.03% | U.S. Total Market | $1 | View on Vanguard |
SCHB·Schwab U.S. Broad Market ETFBest for Schwab Users Charles Schwab | 0.03% | U.S. Total Market | $1 | View on Schwab |
IVV·iShares Core S&P 500 ETF BlackRock (iShares) | 0.03% | U.S. Large Cap (S&P 500) | $1 | View on iShares |
FXNAX·Fidelity U.S. Bond Index Fund Fidelity Investments | 0.025% | U.S. Investment-Grade Bonds | $0 | View on Fidelity |
VXUS·Vanguard Total International Stock ETF Vanguard | 0.08% | International Stocks (Developed + Emerging) | $1 | View on Vanguard |
FZROX — Fidelity ZERO Total Market Index Fund
Fidelity Investments · U.S. Total Market
0.00%
Expense Ratio
VTI — Vanguard Total Stock Market ETF
Vanguard · U.S. Total Market
0.03%
Expense Ratio
SCHB — Schwab U.S. Broad Market ETF
Charles Schwab · U.S. Total Market
0.03%
Expense Ratio
IVV — iShares Core S&P 500 ETF
BlackRock (iShares) · U.S. Large Cap (S&P 500)
0.03%
Expense Ratio
FXNAX — Fidelity U.S. Bond Index Fund
Fidelity Investments · U.S. Investment-Grade Bonds
0.025%
Expense Ratio
VXUS — Vanguard Total International Stock ETF
Vanguard · International Stocks (Developed + Emerging)
0.08%
Expense Ratio
Fidelity Investments · U.S. Total Market
0.00% expense ratio — the lowest possible cost
Vanguard · U.S. Total Market
0.03% expense ratio — effectively free at scale
Charles Schwab · U.S. Total Market
0.03% expense ratio, same as VTI
BlackRock (iShares) · U.S. Large Cap (S&P 500)
0.03% expense ratio — identical to VTI on cost
Fidelity Investments · U.S. Investment-Grade Bonds
0.025% expense ratio — among the lowest for bond funds
Vanguard · International Stocks (Developed + Emerging)
0.08% expense ratio — low for the breadth of coverage
What expense ratio means in real dollars
An expense ratio is deducted daily from the fund's net asset value — you never write a check. On a $10,000 investment over 10 years at 7% annual return: a 0.00% fund grows to approximately $19,672. A fund charging 1.00% — common for actively managed funds — grows to only $17,908, costing you $1,764 in lost compounding. Use our Investment Fee Impact Calculator to run your specific numbers.
How we chose these funds
There are thousands of index funds on the market. The overwhelming majority are unnecessary — narrow sector funds, leveraged products, and "smart beta" strategies that add cost and complexity without improving long-term outcomes for most investors. We filtered for six criteria.
Expense ratio at or near zero
Every fund here charges 0.08% or less per year. We excluded any fund with an expense ratio above 0.10%. The gap between 0.03% and 0.75% — common for active funds — is $720/year on a $100,000 portfolio, and it compounds every year.
Broad diversification
We only included funds that hold hundreds or thousands of securities — not funds concentrated in a single sector, theme, or country. The goal is market exposure, not a bet on a particular niche.
Covers a distinct asset class
Each fund on this list fills a specific role in a portfolio: U.S. equities, international equities, or investment-grade bonds. We excluded funds that substantially overlap with others on the list.
No investment minimum (or effectively $0)
All six funds are accessible to new investors with any amount. ETFs require buying at least one share, but fractional-share programs at major brokerages reduce the practical minimum to $1.
Tracks a recognized, transparent index
FZROX uses a Fidelity-proprietary index — we included it because of its 0.00% cost — but we note this distinction. The other five track widely used benchmarks (CRSP, Dow Jones, S&P 500, Bloomberg U.S. Aggregate, FTSE Global All Cap ex US) with long public track records.
What we excluded: Target-date funds (useful but outside this comparison's scope), sector ETFs (technology, healthcare, energy), factor funds (value, momentum, small-cap tilt), actively managed funds, and any fund with a sales load or 12b-1 fee. We also excluded funds from the comparison if they were substantially duplicative — for example, ITOT (iShares) was left off because it is functionally identical to SCHB and VTI for a typical investor.
Fund details
The table above shows the headline numbers. Here's what actually matters about each fund before you invest — including the less-obvious tradeoffs.
FZROX — Fidelity ZERO Total Market Index Fund
Best OverallFidelity Investments · Mutual Fund · Tracks: Fidelity U.S. Total Investable Market Index
0.00%
Expense Ratio
Best for
Fidelity account holders who want the lowest possible cost for broad U.S. equity exposure
Pros
- +0.00% expense ratio — the lowest possible cost
- +No investment minimum; no trading fees at Fidelity
- +Broad U.S. total market coverage (~2,700+ stocks)
Cons
- –Only available through Fidelity — cannot hold at another brokerage
- –Mutual fund structure means end-of-day pricing, not intraday
- –Fidelity-proprietary index, not a universally recognized benchmark
VTI — Vanguard Total Stock Market ETF
Best for PortabilityVanguard · ETF · Tracks: CRSP US Total Market Index
0.03%
Expense Ratio
Best for
Long-term investors who want broad U.S. market exposure they can hold anywhere
Pros
- +0.03% expense ratio — effectively free at scale
- +Works in any brokerage account, including employer 401(k)s
- +Highly liquid with tight bid-ask spreads; excellent tax efficiency
Cons
- –Marginally higher cost than FZROX for Fidelity account holders
- –ETF structure requires fractional-shares support for investing odd dollar amounts
SCHB — Schwab U.S. Broad Market ETF
Best for Schwab UsersCharles Schwab · ETF · Tracks: Dow Jones U.S. Broad Stock Market Index
0.03%
Expense Ratio
Best for
Schwab account holders who want the lowest-friction, no-fee total market ETF
Pros
- +0.03% expense ratio, same as VTI
- +Commission-free and fractional shares at Schwab
- +Low NAV per share makes it accessible for small investors
Cons
- –Tracks Dow Jones index rather than CRSP — very similar but not identical
- –Slightly less liquid than VTI on a daily volume basis
IVV — iShares Core S&P 500 ETF
BlackRock (iShares) · ETF · Tracks: S&P 500 Index
0.03%
Expense Ratio
Best for
Investors who want to own only the 500 largest U.S. companies and nothing smaller
Pros
- +0.03% expense ratio — identical to VTI on cost
- +Exceptional liquidity and trading efficiency
- +S&P 500 is the most widely recognized U.S. equity benchmark
Cons
- –Excludes mid- and small-cap stocks (roughly 20% of U.S. market)
- –Concentration risk: top 10 holdings represent ~30%+ of the index
FXNAX — Fidelity U.S. Bond Index Fund
Fidelity Investments · Mutual Fund · Tracks: Bloomberg U.S. Aggregate Bond Index
0.025%
Expense Ratio
Best for
Fidelity account holders building a balanced or three-fund portfolio who need bond exposure
Pros
- +0.025% expense ratio — among the lowest for bond funds
- +Tracks the Bloomberg U.S. Aggregate, the standard bond benchmark
- +No minimum; easy to automate contributions
Cons
- –Fidelity-only — cannot transfer to another brokerage as-is
- –Bond funds carry interest rate risk; prices fall when rates rise
- –No inflation protection (no TIPS exposure)
VXUS — Vanguard Total International Stock ETF
Vanguard · ETF · Tracks: FTSE Global All Cap ex US Index
0.08%
Expense Ratio
Best for
Investors building a total world portfolio by pairing U.S. and international index funds
Pros
- +0.08% expense ratio — low for the breadth of coverage
- +True global diversification: developed + emerging markets
- +The natural complement to VTI in a two-fund portfolio
Cons
- –Slightly higher cost than pure U.S. market funds
- –Emerging market volatility adds short-term risk
- –Currency fluctuation affects returns from a USD perspective
Who benefits most
Index funds are the right core holding for most long-term investors — but "most" is not "all." Here's an honest breakdown of who these funds serve well, and when a different approach makes more sense.
Good fit if…
- You're investing for 10+ years and don't need the money in the near term
- You want to minimize time spent on investment decisions
- You're in a Roth IRA, traditional IRA, or taxable brokerage account
- You already have a brokerage account at Fidelity, Vanguard, or Schwab
- You want the market return, not a bet on a single company or sector
Consider alternatives if…
- →You need the money within 1–3 years — consider a high-yield savings account or short-term CDs instead
- →You want hands-off portfolio management with rebalancing — a robo-advisor like Betterment or Vanguard Personal Advisor may be a better fit
- →You're in a 401(k) without these specific funds — choose the lowest-cost total market or S&P 500 index option available in your plan
- →You're drawn to individual stock picking — be aware that over 20-year periods, most active investors underperform a simple total market index fund
Portfolio context: These six funds are building blocks, not a complete strategy. A simple three-fund portfolio — one U.S. equity fund, one international equity fund, and one bond fund — covers the entire global investable market at very low cost. Your allocation between them (e.g., 60% U.S. / 30% international / 10% bonds vs. 80% U.S. / 10% international / 10% bonds) depends on your time horizon and risk tolerance, not on which funds you pick. See our index fund comparison reference and historical returns interactive for more context. Verify all fund details directly before investing — as of March 2026.
Frequently asked questions
What is an index fund and how does it work?
An index fund is a portfolio of securities that mirrors a market index — like the S&P 500 or the total U.S. stock market. Instead of a manager picking stocks, the fund automatically holds everything in the index in proportion to its size. This approach eliminates stock-picking risk and dramatically reduces costs, since there's no research team to pay. When the market goes up, the fund goes up by roughly the same amount. When it falls, the fund falls too.
Should I choose ETFs or mutual fund index funds?
For most long-term investors, the difference is minimal. ETFs trade intraday like stocks, which matters for active traders but is irrelevant for buy-and-hold investors. Mutual funds like FZROX price once daily at market close. The more meaningful considerations are portability (ETFs work at any brokerage; FZROX only at Fidelity) and tax efficiency (ETFs have a structural edge in taxable accounts). If you're investing in a tax-advantaged account like an IRA, either works equally well.
Do I need multiple funds, or can I just hold one?
One broad U.S. fund like FZROX or VTI is a legitimate portfolio. You get 3,000+ stocks in a single holding. Adding international exposure (VXUS) and bonds (FXNAX) reduces dependence on any one market and generally smooths volatility — but neither is mandatory. Many reputable investors advocate for a simple one or two-fund portfolio and hold it for decades. Complexity does not equal better outcomes.
Is there a tax impact I should know about?
In tax-advantaged accounts (IRAs, 401(k)s), taxes are deferred or eliminated — fund type doesn't matter from a tax perspective. In taxable brokerage accounts, ETFs are generally more tax-efficient than mutual funds because of how redemptions work. FZROX's mutual fund structure can create small capital gains distributions in taxable accounts. For this reason, most advisors suggest using FZROX in retirement accounts and ETFs like VTI or SCHB in taxable accounts.
What return should I expect from these funds?
No one can promise future returns. As a reference point, the U.S. total stock market has returned roughly 9–10% annually over long historical periods, while international stocks and bonds have varied more. Over shorter periods — including individual years or even decades — results can be very different. The case for index funds is not that they guarantee returns, but that they capture whatever the market delivers without paying extra for an active manager who, historically, underperforms the index after fees over 15+ year periods.
Ready to start investing in index funds?
You need a brokerage account first. Both funds below are available with no minimums and no trading fees at their home institution.