ACCOUNT GUIDE / 401(K)
2026 edition
ACCOUNT-TYPE FRAMEWORK
ETF vs index fund in your 401(k)
The honest answer: your 401(k) probably does not offer ETFs. The decision is which mutual fund in your plan menu, not which wrapper.
Quick answer
ETFs are almost never offered in 401(k) plans.
401(k) plan recordkeeping is built around mutual funds: daily NAV pricing, automatic payroll-deduction contributions, target-date series. ETFs do not fit cleanly. Focus on two things: capture the full employer match, and pick the cheapest broad-index option in your plan menu.
FIG. A / READING YOUR PLAN MENU
What you are likely to see in a typical 401(k) lineup
Your specific plan may have institutional share classes that are cheaper than the retail tickers. Look in the summary plan description or the fund fact sheets for the exact expense ratios you are paying.
FIG. B / THE ONE NUMBER THAT MATTERS
Expense ratio compounds for decades
Compare a 0.05% expense ratio fund (look up your specific fund on Morningstar or in the prospectus filed on SEC EDGAR) and a 0.50% expense ratio fund, both holding similar equity index exposure, on a $500 monthly contribution over 30 years at a 7% gross assumed return: the cheap fund ends up roughly $40,000 to $60,000 ahead of the expensive one, depending on assumptions. That is real money. The fund-selection decision inside a 401(k) menu has more dollar impact than the ETF-versus-mutual-fund debate ever will.
If your plan menu offers an actively managed large-cap equity fund at 0.80% next to a broad index fund at 0.05%, the index fund is almost always the right choice. Most active funds underperform their benchmark over long horizons after fees. The expense ratio is the single best predictor of forward returns for index-style strategies.
Cheap index fund
0.05%
~$50/year on $100,000
Typical active fund
0.80%
~$800/year on $100,000
30-year cost gap
~$50k+
Compounded on $500/month
FIG. C / THINGS TO WATCH OUT FOR
Common 401(k) traps
Expensive target-date series.
Some plan sponsors default new participants into a target-date fund with a 0.60% or higher expense ratio. If your plan offers a separate index target-date series at lower cost, switching can save tens of thousands over a career.
Company stock concentration.
Holding more than 5-10% of your retirement savings in your employer's stock is a concentration risk. If the company has a bad year, you lose your job and your retirement balance at the same time.
Ignoring the employer match.
Whatever the match formula is (50% of your first 6%, dollar-for-dollar to 4%, etc.), contributing enough to capture the full match is the highest-priority decision. The match is an immediate 50-100% return on those dollars. Pick a fund afterwards.
Unnecessarily complicated allocation.
You do not need to hold seven funds in a 401(k). One target-date index fund or a three-fund split (US index, international index, bond index) is sufficient. Simplicity beats complexity over decades.
FIG. D / AFTER YOU LEAVE THE EMPLOYER
Rolling a 401(k) to an IRA opens the wrapper choice back up
Once you separate from an employer, you can roll the 401(k) balance into a Traditional IRA (or Roth IRA, with a tax event under IRS Publication 590-A rules). Inside an IRA, the entire ETF and mutual fund universe opens up. The expense ratios available outside a typical 401(k) plan are often meaningfully lower (think 0.03% VOO vs 0.20% institutional active funds). The rollover also consolidates accounts as you change jobs, which is its own win.
The rollover process: open an IRA at a brokerage, request a direct rollover from the former employer's plan recordkeeper, the funds move trustee-to-trustee without a tax event, and you reinvest in your chosen funds. This is also when the ETF wrapper becomes a real option for the first time. See our Roth IRA guide for specific fund picks.
DESK Q&A
Frequently asked
Q01Can I buy ETFs in my 401(k)?
Almost certainly not. Standard 401(k) plan recordkeeping (Fidelity Workplace, Empower, Vanguard Retirement Plan Services, etc.) is built around mutual fund infrastructure. A small number of plans support a brokerage window that allows individual security purchases including ETFs, but those windows are uncommon and often discouraged by plan sponsors. Assume your 401(k) menu is mutual funds only.
Q02What is the cheapest fund I can pick in a 401(k)?
It depends on your plan menu. Look for a broad index fund with the lowest expense ratio: an S&P 500 index, a total US market index, or an institutional share class of a Vanguard or Fidelity index fund. Anything under 0.10% is good. Anything under 0.05% is excellent. Avoid the menu's actively managed funds at 0.50%+ unless you have a specific reason.
Q03Should I contribute to my 401(k) or to a Roth IRA first?
Standard order: contribute to the 401(k) up to the full employer match first (free money), then max out a Roth IRA, then come back to the 401(k) up to the annual contribution limit. This is a generalisation. Specific situations like high income or high expected retirement bracket can change the order. Worth talking through with a fee-only fiduciary advisor.
Q04Are target-date funds in 401(k) plans good?
Index target-date funds are usually fine. Vanguard, Fidelity Freedom Index, and Schwab target-date series run at low expense ratios with sensible glide paths. Actively managed target-date series often run more expensive without justification. Check the expense ratio of your plan's default target-date fund. If it is over 0.30%, look for an index alternative in the menu.