Best Index Funds 2026

The quick answer

The best index fund for most investors is either VTI (Vanguard Total Stock Market ETF) or FZROX (Fidelity ZERO Total Market Index Fund). Both give you the entire US stock market at near-zero cost. If you hold in a taxable brokerage account, VTI (an ETF) is slightly more tax-efficient. If you hold in a tax-advantaged account (IRA, 401k) and use Fidelity, FZROX has zero expense ratio. For international exposure — which most financial advisors recommend — add VXUS (Vanguard Total International Stock ETF) or FZILX (Fidelity ZERO International Index). Together, VTI + VXUS gives you the entire investable world market at roughly 0.05% combined cost.

Why index funds win

The evidence for passive index investing is overwhelming and has been for decades. Over any 15-year period in US market history, 85-95% of actively managed mutual funds underperform their benchmark index after fees. The math is not subtle: a fund charging 1% annually in expenses faces a 1% annual return headwind versus a fund charging 0.03-0.05%. Over 30 years, this difference on a $100,000 initial investment compounds to roughly $175,000 in lost gains assuming 7% nominal returns.

The three reasons active managers consistently underperform:

Fees: Active management costs money. Portfolio managers, analysts, and trading desks need to be paid. These costs come out of your returns.
Turnover: Active funds trade more frequently, generating taxable events in taxable accounts and transaction costs in all accounts.
Market efficiency: Major markets incorporate publicly available information rapidly. Identifying mispriced securities with enough consistency to overcome the fee drag is exceptionally rare.

This does not mean no active manager ever outperforms. It means identifying which managers will outperform in advance, before the fact, is not reliably possible — and paying 1% to take that bet is negative expected value.

Key metrics: what to look for in an index fund

Expense ratio: Annual cost as a percentage of assets. US total market index funds now go as low as 0.00% (Fidelity ZERO). For ETFs, 0.03-0.05% is standard. Anything above 0.20% is unjustifiably expensive for a passive index product.
Index tracked: Most total market funds track CRSP US Total Market Index, Russell 3000, or a Wilshire 5000 equivalent. These are functionally similar — all capture small, mid, and large-cap US stocks. S&P 500 funds capture only large-cap (500 companies) and exclude small and mid-cap. The long-run performance difference between total market and S&P 500 is small but total market is more diversified.
Fund size and liquidity: Larger funds have tighter bid-ask spreads (for ETFs) and are less likely to be closed or merged. Funds with assets below $100 million carry meaningful closure risk.
Tax efficiency: ETF structure is generally more tax-efficient than mutual fund structure in taxable accounts because ETFs can avoid distributing capital gains. For tax-advantaged accounts, this distinction doesn't matter.
Dividend yield: Total market index funds distribute dividends quarterly. In taxable accounts, these create a tax event each quarter regardless of whether you sold anything. This is normal and expected — account for it in tax planning.

Best US total market index funds

VTI — Vanguard Total Stock Market ETF

Expense ratio: 0.03%
Index tracked: CRSP US Total Market Index
Assets under management: $440+ billion
Holdings: ~3,700 stocks, market-cap weighted
Dividend yield: ~1.3%

VTI is the gold standard. It has the largest asset base of any total market ETF, which minimizes tracking error and keeps bid-ask spreads near zero. The 0.03% expense ratio is effectively zero on a practical basis — $30/year on $100,000 invested. VTI is available at any brokerage. In taxable accounts, its ETF structure means capital gains distributions are rare. This is the fund most index fund advocates use as their core US equity holding.

FZROX — Fidelity ZERO Total Market Index Fund

Expense ratio: 0.00%
Index tracked: Fidelity U.S. Total Investable Market Index (proprietary)
Assets under management: $18+ billion
Holdings: ~2,700 stocks
Dividend yield: ~1.3%

FZROX has a literal zero expense ratio — Fidelity uses it as a customer acquisition tool and subsidizes the cost. It tracks a proprietary Fidelity index (not the same as CRSP), holds slightly fewer stocks, and is available only at Fidelity (you cannot transfer FZROX to another brokerage — it would force a sale). In a Fidelity IRA or 401(k), FZROX is compelling. In a taxable account, the lock-in to Fidelity and slightly different composition makes VTI or FSKAX a better choice for most investors.

FSKAX — Fidelity Total Market Index Fund

Expense ratio: 0.015%
Index tracked: Dow Jones U.S. Total Stock Market Index
Assets under management: $80+ billion
Holdings: ~3,800 stocks

FSKAX is Fidelity's mutual fund equivalent to VTI with a 0.015% expense ratio. It holds more stocks than FZROX and tracks an external index rather than a proprietary one. For Fidelity users who want a transferable mutual fund (you can convert FSKAX shares to FZROX's brokerage equivalent), FSKAX is the better option than FZROX for taxable accounts.

SWTSX — Schwab Total Stock Market Index Fund

Expense ratio: 0.03%
Index tracked: Dow Jones U.S. Total Stock Market Index
Assets under management: $19+ billion

Schwab's total market fund matches VTI's expense ratio and is the natural choice for Schwab account holders. Functionally equivalent to FSKAX. The Schwab equivalent ETF is SCHB (0.03%), which is tradeable at any brokerage.

Best S&P 500 index funds

S&P 500 funds capture the 500 largest US companies (approximately 80% of total US market cap by weight). The performance difference between S&P 500 and total market funds has been minimal historically, with small-cap tilts occasionally outperforming. For simplicity and near-identical long-term results, S&P 500 funds are a valid substitute for total market.

VOO (Vanguard S&P 500 ETF) — 0.03% expense ratio, $450B+ AUM, the most widely held ETF in the world. The default choice for S&P 500 exposure.
FXAIX (Fidelity 500 Index Fund) — 0.015% expense ratio, Fidelity's S&P 500 mutual fund. Slightly cheaper than VOO and accessible with no minimum investment.
SWPPX (Schwab S&P 500 Index Fund) — 0.02% expense ratio, Schwab's equivalent. No minimums.
IVV (iShares Core S&P 500 ETF) — 0.03% expense ratio, BlackRock's ETF. Equivalent to VOO in performance and cost; some traders prefer IVV's liquidity profile.

Best international index funds

Most financial advisors recommend holding 20-40% of equity exposure in international stocks. The US has dramatically outperformed international markets over the past 15 years, which has made many investors skeptical of international exposure. This is recency bias — the relative performance of US vs. international markets has cycled throughout history, and concentration in one country is meaningful risk.

VXUS (Vanguard Total International Stock ETF) — 0.08% expense ratio, covers developed and emerging markets outside the US. The standard complement to VTI for total world coverage.
FZILX (Fidelity ZERO International Index Fund) — 0.00% expense ratio, Fidelity-only, proprietary index. Same lock-in caveat as FZROX.
IXUS (iShares Core MSCI Total International Stock ETF) — 0.07% expense ratio, BlackRock's international ETF. Tracks the MSCI ACWI ex US index.
VEA (Vanguard Developed Markets Index Fund ETF) — 0.06%, developed markets only (no emerging). Lower volatility than VXUS but less diversification.

The three-fund portfolio

The simplest evidence-backed portfolio for long-term investors:

US total market: VTI or equivalent (~60% for moderate international exposure, higher if you want US-heavy)
International total market: VXUS or equivalent (~30%)
Bond index: BND (Vanguard Total Bond Market ETF, 0.03%) or FXNAX (Fidelity U.S. Bond Index, 0.025%) (~10% if young/aggressive, higher if near retirement)

The exact allocation depends on your time horizon and risk tolerance. A 30-year-old with a 35-year investment horizon might hold 90% equities (60% US / 30% international) and 10% bonds. A 60-year-old approaching retirement might shift to 60% equities and 40% bonds. Annual rebalancing to target allocations is the only active management required.

Where to buy index funds

Index funds are available at any major brokerage:

Vanguard: Best for buy-and-hold investors who want Vanguard funds directly. No account minimums for ETFs. Interface is dated but functional.
Fidelity: Best overall brokerage for index fund investors. $0 minimums, excellent research tools, FZROX available, and the best customer service in the industry.
Schwab: Strong competitor to Fidelity with excellent tools, $0 commissions, and no minimums.
Vanguard ETFs (VTI, VXUS, BND) are available at any brokerage — you do not need a Vanguard account to buy Vanguard ETFs.

Common mistakes

Holding too many funds: VTI + VXUS + BND is a complete portfolio. Adding more funds typically adds overlap, not diversification. Many investors hold 10 index funds that are 80% correlated with each other.
Market timing: Waiting for a "better entry point" is attempting to time the market. Time in the market beats timing the market. The best time to invest was yesterday; the second best time is now.
Selling during downturns: The permanent loss of capital in index investing requires selling at the bottom. Paper losses are temporary as long as you don't sell. The investors who got hurt in 2008-2009 and 2020 were those who sold — not those who held.
Chasing performance: The funds that performed best last year are not the ones that will perform best next year. This year's winner is rarely next year's winner. Pick your allocation based on asset class exposure, not recent returns.
Ignoring tax location: Hold your bond index in tax-advantaged accounts (IRA, 401k) and your stock index ETFs in taxable accounts. Bonds generate ordinary income taxed at your marginal rate; ETFs generate mostly qualified dividends taxed at lower capital gains rates.

The bottom line

The best index fund strategy is simple enough to fit on an index card: buy VTI (or FZROX at Fidelity), add VXUS for international exposure, hold BND for bonds based on your timeline, rebalance annually, and don't sell when markets drop. You will outperform the majority of professional fund managers over any 15-year period. The difficulty is not intellectual — it is behavioral. The strategy only works if you stick to it through the inevitable 30-50% market drawdowns that will happen in any long investment career.

Expense ratios and fund data as of May 2026. Verify current fund details and availability directly with fund providers before investing.