Glide Paths as Horizon Shifts
Glide Paths as Horizon Shifts
When you're 25, you can hold 90/10 stocks and bonds. When you're 55, you probably shouldn't. The question is not whether to shift toward bonds but when and how. A glide path is a systematic de-risking curve: as your time horizon shortens (years until retirement), your equity exposure falls on a preset schedule. Target-date funds automate this. The debate, surprisingly, is whether to stop de-risking at retirement ("to") or continue adjusting through retirement ("through").
Key takeaways
- A glide path is a predetermined shift from equities to bonds as time horizons shorten. Common paths reduce equity by 1–2% per year.
- Target-date funds like VFIAX (Vanguard's 2050 fund) automate glide paths. You pick your likely retirement year, and the fund rebalances internally every quarter.
- The "to" approach stops de-risking at retirement; the "through" approach continues reducing equity throughout retirement.
- "Through" glide paths are now standard and more defensible: they recognize that retirement is 30+ years, not a single moment.
- A self-directed glide path (manual rebalancing) works but requires discipline; most people do better with a target-date fund.
Why glide paths exist
Picture two timelines:
Alex at 25: Earns $50,000 per year, has 40 years until retirement. An 80/20 allocation is reasonable: time absorbs volatility. A 40% crash in 2028 is painful but irrelevant; he has 32 years to recover.
Alex at 60: Still employed, but retirement is 5 years away. The same 80/20 allocation is now dangerous. A 40% crash would cost him $200,000 (if he has $500,000 invested). He cannot wait 32 years to recover; he needs the money in 5 years. A 40/60 allocation is more appropriate.
The glide path connects these two states. It's not a single allocation that fits all ages. It's a curve that shifts over decades. At 25, you hold lots of equities. Each year, you drift slightly more conservative. By 60, you hold mostly bonds and a strategic equity allocation for growth during your 30-year retirement.
How glide paths work: The math
A simple glide path rule: "Age in bonds." If you're 30, hold 30% bonds and 70% stocks. If you're 50, hold 50% bonds and 50% stocks. If you're 70, hold 70% bonds and 30% stocks.
This rule is crude but easy. A more refined version: "Reduce equity by 1% per year." Start at 80% equity at 25, and reduce by 1% annually. At 35, you're at 70% equity. At 55, you're at 50% equity. At 65, you're at 30% equity.
A target-date fund embeds this curve internally. VFIFX (Vanguard 2050 Target-Date Fund) is designed for someone retiring around 2050. The fund currently holds about 90% stocks and 10% bonds. As 2050 approaches, the fund's algorithm reduces equity gradually. By 2050, the fund shifts to a more conservative "in-retirement" allocation (around 40% stocks, 60% bonds).
The key point: You don't think about rebalancing. The fund does it for you every quarter. Your allocation evolves whether you pay attention or not.
"To" vs "Through" glide paths
Historically, the financial industry used "to" glide paths: you de-risked until retirement, then stopped. Your allocation froze at retirement. A typical "to" path might reach 30% equity by age 65 and stay there.
The problem: If you're 65 and retiring with $1 million, you need that to last 30+ years (to age 95+). A 30% equity portfolio earns around 4–5% per year. A 60% equity portfolio earns around 6–7% per year. Over 30 years, the higher equity allocation makes a huge difference. But if you panic-sell equities during a crash in your first years of retirement, you're in trouble.
Modern "through" glide paths continue adjusting throughout retirement. You might reach 50% equity at age 65, then reduce to 40% at 70, 30% at 80, and 20% at 90. This recognizes that "retirement" is not a single moment but a 30-year period. Your allocation in your first retirement year (when you still might return to work) is different from your allocation at 80 (when you definitely won't).
The trade-off: "Through" paths reduce growth but increase psychological safety. You're accepting slightly lower returns in exchange for holding steady through crashes. For most people, this is the right trade.
Target-date funds: How to use them
A target-date fund is simple: You pick your expected retirement year, invest in that fund, and ignore it.
Example: You're 35 with 30 years until retirement (age 65 in 2054). You invest in VFIFX (Vanguard 2054 Target-Date Fund). The fund currently holds 90% stocks. Each year, as you age and 2054 approaches, the fund drifts more conservative automatically. By 2054, it will hold around 45% equity and 55% bonds. You never think about rebalancing. You never manually reduce your equity. The fund does it.
The cost: Vanguard's target-date funds charge 0.08% per year. Fidelity's freedom funds charge 0.50% per year. Both are reasonable. You're paying for the automation and the peace of mind of a professional glide path.
Which target-date fund to pick? Match your expected retirement year:
- VFFVX (Vanguard 2045 Target-Date Fund) if you're retiring around 2045
- VFIFX (Vanguard 2050 Target-Date Fund) if you're retiring around 2050
- VFIFX (Vanguard 2055 Target-Date Fund) if you're retiring around 2055
If your retirement date falls between these, pick the fund closest to your actual retirement date. Don't try to engineer a blended approach.
Building your own glide path
If you prefer manual control, you can build a glide path yourself. The mechanics are simple:
Step 1: Pick your starting allocation. At age 25, you might start at 85/15 stocks and bonds.
Step 2: Set a reduction schedule. Reduce equity by 1% per year.
- Age 25: 85% equity
- Age 30: 80% equity
- Age 40: 70% equity
- Age 50: 60% equity
- Age 60: 50% equity
- Age 70: 40% equity
Step 3: Automate the rebalancing. Once a year, on your birthday or at year-end, rebalance to the target allocation. If you're supposed to be at 60% equity and you're at 65% (because stocks outperformed), sell enough stocks to hit 60%. If you're at 55%, buy stocks.
Step 4: Simplify with funds. Use broad index funds to make rebalancing easy:
- Stocks: VTI (U.S.) + VXUS (international) or just VTSAX + VTIAX
- Bonds: BND or VBTLX
The math is straightforward. If you have $500,000 and you want 60% equity, you hold $300,000 in stocks and $200,000 in bonds. Every quarter or year, you check. If stocks have grown to $320,000 (because the market was up), you sell $20,000 of stocks and buy bonds.
When to stop de-risking
A common question: At what age should you stop reducing equity? In the "to" model, you'd stop at retirement (65). In the "through" model, you'd continue reducing until you're very old (80+).
Practical answer: Reduce equity until you reach a floor of 20–30% equity. Even at age 85, you probably have 10+ years left. Some equity exposure helps your portfolio outpace inflation. A fully-bond portfolio at age 85 might grow at 3–4% annually (after inflation, near-zero). A 30% equity portfolio grows at 4–5% (after inflation, 1–2%). That 1–2% difference compounds significantly over a decade.
So a glide path might look like:
- Age 25–65: Reduce from 85% to 40% equity
- Age 65–80: Reduce from 40% to 25% equity
- Age 80+: Hold 25% equity (stop de-risking)
Glide paths for the self-employed
If you're self-employed or own a business, your glide path might differ. You probably have a lumpy income (some years great, some years poor). You might reduce equity more aggressively in years when business is strong, because you have cash flow to pay bills. You might hold more equity in years when business is weak, because you're not drawing from the portfolio.
For the self-employed, a target-date fund is even more valuable: it removes the need to time rebalancing around business cycles. You invest and the fund handles the de-risking automatically, no matter how your income fluctuates.
The psychological benefit of automation
Here's the hidden advantage of glide paths (especially target-date funds): They remove the temptation to time the market or panic-adjust. You can't see the glide path and think "maybe I should reduce equity faster because I'm worried about a crash." The fund rebalances on its schedule, and you live with it.
This is not laziness. It's anti-fragility. By making rebalancing automatic and predictable, you avoid emotional overrides. You're forced to de-risk consistently, which is the right behavior.
Common glide-path mistakes
Mistake 1: Picking the wrong target-date fund. You're retiring at 62 but you pick the 2040 fund (which assumes retirement at 2040, or age 76 if you're 25 now). You're under-de-risking. Pick the fund closest to your actual retirement year, not your age.
Mistake 2: Stopping de-risking too early. You reach 60%, equity and you think "that's enough." But you still have 20 years until retirement. A 60% equity allocation at age 45 is too aggressive if you're not comfortable with a 35% crash at age 55. Keep de-risking.
Mistake 3: Mixing target-date funds with manual adjustments. You're in VFIFX (which is automatically de-risking), but you also manually reduce equity every year. You're de-risking twice, which is too aggressive. Pick one approach and stick to it.
Mistake 4: Confusing glide path with passive indexing. A glide path is not just holding a simple portfolio. It's a changing portfolio. Some people buy a simple 60/40 portfolio and keep it flat, thinking that's a glide path. It's not. A real glide path shifts.
Related concepts
Next
Glide paths solve the question of when to shift away from equities. But what bond allocation you hold at each life stage is a separate question. The next article examines bond cushions and the different formulas—age-in-bonds, 100-minus-age, 110-minus-age—and which one survives scrutiny.