There's a good chance your 401k has two target date funds that look almost identical on the menu. One says "Fidelity Freedom 2040." The other says "Fidelity Freedom Index 2040." Or your plan might show "Vanguard Target Retirement 2040" alongside a plan-specific target date option from an insurance company or asset manager you've never heard of. Most people pick one based on the name, or because a colleague mentioned it, or because it was the default. Then they never think about it again.
The difference between these two products is not a minor technicality. At a 0.75% expense ratio versus 0.12%, the cost gap on a $50,000 balance over 25 years — with no additional contributions — is approximately $34,000 in lost wealth. Add in ongoing 401k contributions and the number climbs further. The performance difference between the active version and the index version is not better returns in the active fund — it's worse returns, because the fee comes directly out of your compounding. Here is exactly what these two products are, how to tell which one you have, and what the decision to switch actually looks like.
What a Target Date Fund Is and Why It Became the Default 401k Option
The Automatic Rebalancing That Makes These Funds Genuinely Useful
A target date fund (also called a lifecycle fund) is a single mutual fund that holds a diversified mix of stocks and bonds and automatically adjusts that mix as you approach your projected retirement year. A 2040 fund today — with roughly 15 years until the target date — holds approximately 70-75% stocks and 25-30% bonds. As 2040 approaches, the fund gradually shifts toward more bonds and fewer stocks, following what fund companies call a "glide path."
The core appeal: one investment, automatic rebalancing, appropriate risk for your time horizon without any manual management. The 2006 Pension Protection Act made target date funds the default investment option for 401k plans that use automatic enrollment — which is why hundreds of millions of dollars flowed into them without participants actively choosing them. If you started a new job after 2006 and never changed your 401k investment election, there's a reasonable chance you're in a target date fund right now.
Target date funds work exactly as advertised for a specific problem: keeping long-term retirement savers appropriately diversified without requiring them to monitor and rebalance their portfolio. Research from Vanguard consistently shows that the average individual investor underperforms the funds they hold by approximately 1.5% per year due to behavioral mistakes — panic selling during downturns, chasing recent performance, over-concentrating in company stock. A target date fund eliminates all of those decisions by making the investment automatic. For someone who would otherwise move everything to cash during a market drop or never rebalance, the target date fund is genuinely the right answer.
What the fund design doesn't address is the cost of the wrapper around that automatic rebalancing. And that cost varies by more than most investors expect.
Active vs Index Target Date Funds: Two Very Different Cost Structures
Why Fidelity Freedom and Fidelity Freedom Index Are Not the Same Product
Target date funds come in two primary varieties:
Index-based target date funds: The underlying holdings are index funds tracking broad market benchmarks (total US stock market, international stocks, US bonds). No active stock selection. The glide path management is the only human decision involved. Expense ratios: Vanguard Target Retirement series (0.08-0.15%), Fidelity Freedom Index series (0.12%), Schwab Target Date Index series (0.13-0.15%), BlackRock LifePath Index (0.10-0.14%).
Actively managed target date funds: The underlying holdings include actively managed stock and bond funds, with portfolio managers making security selection decisions. Expense ratios: Fidelity Freedom series (non-index) (0.47-0.75%), American Funds Target Date series (0.30-0.72%), T. Rowe Price Target series (0.57-0.70%). Employer-selected insurance company target date options can be even higher — 0.75%-1.5% is not unusual in smaller 401k plans.
The key insight: both versions give you the same basic product — automatic glide path rebalancing toward your target retirement year. What you're paying the higher fee for in the active version is active fund management in the underlying holdings. And decades of data on actively managed funds vs index funds show that active managers do not consistently outperform their benchmarks after fees. The higher expense ratio in the active target date fund typically produces lower long-term returns than the index version, not higher — because you're paying 0.60 percentage points per year more for performance that, on average, trails the market.
The 25-Year Math: What 0.63% in Annual Fees Costs on $50,000
The Numbers That Make the Difference Concrete
Expense ratios are deducted from your fund's net asset value daily — you never see a bill, which makes them easy to ignore. But the drag on compounding is real and cumulative.
Assume a $50,000 balance in a target date fund with no additional contributions, a 7% gross annual market return, and a 25-year holding period:
Fidelity Freedom Index 2040 at 0.12% expense ratio:
Net annual return: 7% − 0.12% = 6.88%
Balance after 25 years: $50,000 × (1.0688)^25 = ~$268,000
Fidelity Freedom 2040 (active) at 0.75% expense ratio:
Net annual return: 7% − 0.75% = 6.25%
Balance after 25 years: $50,000 × (1.0625)^25 = ~$230,000
Cost of choosing the active version: approximately $38,000 over 25 years on the same $50,000 starting balance.
Now add ongoing contributions of $500/month for 25 years at the same net returns:
Index version at 6.88%: combined balance grows to approximately $478,000
Active version at 6.25%: combined balance grows to approximately $434,000
Difference with ongoing contributions: approximately $44,000
This is the cost of the fee difference — nothing else. Same market, same allocation strategy, same automatic rebalancing. You're paying $44,000 over 25 years for active management that decades of research show produces no systematic outperformance.
These numbers assume the active fund tracks the index fund's returns before expenses, which is a generous assumption. Academic research on active fund performance (including the SPIVA scorecards published by S&P Dow Jones Indices) consistently shows that 80-90% of actively managed funds underperform their benchmark index over 15-year periods after fees. The active target date fund doesn't just cost more in fees — it is also likely to underperform its index equivalent on a gross return basis over long holding periods. The fee math above likely understates the total performance gap.
For the broader context of how expense ratios destroy long-term 401k wealth — including the comparison between a 1% expense ratio and a 0.05% fund over 30 years on a larger starting balance — our detailed analysis of what a 1% expense ratio costs vs a 0.05% fund over 30 years walks through the identical compounding math at a higher fee differential.
How to Check What's in Your 401k Right Now
The Three-Minute Review That Could Be Worth $44,000
Log into your 401k plan website (Fidelity, Vanguard, TIAA, Principal, Empower, John Hancock, etc.) and navigate to your current holdings. Find the expense ratio for each fund you hold — it should be listed as a percentage or accessible by clicking on the fund name. If you can't find it on the plan website, the fund's expense ratio is listed in its prospectus or on any financial data site (Morningstar, the fund company's website) by searching the fund name or ticker symbol.
Target date fund expense ratios to flag:
Under 0.20%: Excellent — you're in an index-based version, probably Vanguard, Fidelity Index, or Schwab. No action needed.
0.20% – 0.40%: Reasonable for employer-negotiated plan options; check if a lower-cost alternative exists in the same plan.
0.40% – 0.75%: High — this is almost certainly an actively managed target date fund or a plan-specific option with markups. Look for an index alternative.
Above 0.75%: Very high — common in smaller plans using insurance company products. Worth considering your lowest-cost individual index fund options as an alternative if this is your only target date fund option.
If your 401k plan includes multiple target date series, look for the word "Index" in the fund name. Fidelity Freedom Index vs Fidelity Freedom. Vanguard Target Retirement vs a plan-specific active option. The "Index" version is almost always substantially cheaper.
When to Skip the Target Date Fund Entirely
The Cases Where Building Your Own Portfolio Makes More Sense
Target date funds are excellent when: you want automatic rebalancing, you're not confident in picking and managing individual funds, and your plan offers a low-cost index version. They are a suboptimal choice when:
Your plan only offers expensive active target date funds AND offers cheap index funds. If your 401k's target date fund costs 0.75% but offers a total stock market index fund at 0.03%, the three-fund portfolio (total US stock + international + US bond index) at 0.03-0.05% blended beats the target date fund by more than the rebalancing convenience is worth. You'd need to manually rebalance once a year — 20 minutes — to capture the full advantage. The decision is whether 20 minutes per year is worth $44,000 over 25 years.
You have significant taxable (non-retirement) account holdings. Target date funds held in taxable accounts generate taxable capital gains distributions annually from internal rebalancing — even in years when you don't sell anything. Holding target date funds in tax-advantaged accounts (401k, IRA, Roth IRA) is appropriate. Holding them in taxable brokerage accounts is tax-inefficient. Our comparison of taxable brokerage vs additional 401k contributions after maxing a Roth IRA covers how to think about account type and investment placement together. And for understanding the broader difference between ETFs (which can avoid these capital gains distributions) and mutual funds (which often can't), our guide to ETFs vs mutual funds for 401k and taxable accounts covers the structural difference that matters for tax efficiency.
Two books worth having alongside your 401k decisions: The Little Book of Common Sense Investing by John Bogle is the original case for low-cost index funds over active management — Bogle founded Vanguard and invented the index fund, and his argument for why expense ratios matter more than fund manager skill holds up completely in the target date fund context. And The Simple Path to Wealth by JL Collins covers the practical 401k investment strategy that flows from Bogle's principles — specifically the case for keeping the investment decision as simple as possible, which for most 401k participants means a low-cost index target date fund and nothing else.