Rebalancing once a year vs never:
what the trade-off actually looks like
Should you reset your portfolio back to target weights every year, or set it once and let it drift? This study models a simple 60/40 UCITS portfolio over 20 years with and without annual rebalancing — comparing final growth, drawdown, and the equity weight you actually end up with.
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What the 20-year model shows
Stylized 60/40 portfolio (global equities + high-quality bonds). Both strategies start at 1.00x from the same lump sum. CAGR and drawdown figures are illustrative and consistent with the chart path.
- Equity weight stays close to your original 60% target throughout.
- Drawdowns are shallower because the bond sleeve is replenished each year.
- Slightly lower end value — the cost of buying back into bonds as stocks run.
- Consistent with your written risk plan and investment policy statement.
- Equity weight can silently drift to 75–85% after a long bull market.
- Slightly higher end value — letting winners compound uninterrupted.
- Larger drawdowns when equities correct from an elevated weight.
- Requires accepting a risk profile that changes without a deliberate decision.
How the model works
We model two investors who start with the same 60% global stocks / 40% high-quality bonds portfolio — calibrated to broadly accessible UCITS equivalents (e.g. IWDA or VWCE for equity, AGGH or VAGP for bonds). Both portfolios start at 1.00x. Both experience the same return path each period.
The only difference is what happens to the allocation over time. Never Rebalance sets 60/40 once and lets weights drift as markets move. Rebalance Annually resets back to 60/40 stocks and bonds once per year.
We use a stylized 20-year path with dividends and interest reinvested. Taxes and transaction costs are excluded to isolate the pure effect of drift vs annual rebalancing. This is an illustration, not a forecast or backtest of real index data.
Normalized growth: rebalanced vs drifting (20 years)
Both portfolios start at 1.00x. The gap reflects the core trade-off: letting equity take over versus keeping risk closer to target. The drifting portfolio slightly outperforms in growth, but with more downside exposure late in the run.
Stylized chart for intuition. Real outcomes vary by asset class, time period, fees, taxes, and the exact rebalance rule used.
What the data actually says
Over 20 years, the CAGR difference between rebalanced and drifting is roughly 0.4 percentage points in this model. That is not nothing, but it is far smaller than most investors expect — and it runs in both directions depending on the period.
The drifting portfolio shows a deeper max drawdown (-24% vs -20%) because by the time a correction hits, it has silently become an 80/20 portfolio. Four percentage points of extra drawdown on a large balance is real money — and real emotional stress.
After a strong equity decade, a never-rebalanced 60/40 portfolio can drift to 78–85% equities. At that point the investor is running a very different risk profile than the one they planned. Rebalancing is not primarily a return strategy — it is a tool for keeping the portfolio you actually intended to hold.
For UCITS investors using accumulating funds (e.g. IWDA Acc, VWCE), rebalancing is purely a sell-and-buy operation with no automatic dividend reinvestment to lean on. This makes conscious rebalancing decisions more important, not less.
When annual rebalancing makes sense — and when drift is tolerable
- Chose your allocation because it matched your genuine risk tolerance — and that tolerance has not changed.
- Do not want a quiet drift toward 80/20 or 90/10 without making a deliberate decision.
- Want a calendar rule that removes ad-hoc, emotion-driven trades.
- Are approaching a goal (retirement, purchase) where drawdown risk matters.
- Have a simple two-fund setup where annual rebalancing costs very little.
- Have a long horizon and genuinely high risk tolerance that has been tested.
- Are soft-rebalancing via contributions — directing new cash into the underweight asset each month.
- Started conservatively and are comfortable drifting slightly more aggressive over time.
- Monitor actual weights at least annually and have a clear cap on how far equity can drift.
- Understand that letting drift continue is an active, deliberate bet — not a passive default.
Side-by-side comparison
| Strategy | CAGR | Max drawdown | Worst 12-month | Equity drift (yr 20) |
|---|---|---|---|---|
| 60/40 Never Rebalance | approx 9.4% | approx -24% | approx -20% | approx 80%+ |
| 60/40 Rebalance Annually | approx 9.0% | approx -20% | approx -17% | approx 60% |
Stylized values consistent with the chart path. Real outcomes depend on assets, period, taxes, costs, and your exact rebalance rule. Not a backtest of any specific index.
Keep your rebalancing effortless
Rebalancing is only as good as the platform you use to execute it. IBKR gives European investors multi-currency accounts, limit-order control, and direct access to the widest UCITS ETF selection — well suited to disciplined annual rebalancing. For automated savings plans that soft-rebalance by design, Trade Republic lets you set target weights and automate monthly contributions. Use TradingView to track ETF allocation visually.
Some of the links above are affiliate links. We may earn a commission at no extra cost to you. Educational content only — not personalized investment advice.
Go deeper
Common questions
Is rebalancing once per year really enough?
For a simple stock/bond mix, annual rebalancing is usually enough. The goal is not to chase every market move, but to prevent slow drift from materially changing your actual risk exposure. More frequent rebalancing rarely adds enough value to justify the extra cost and complexity.
Does rebalancing improve returns or mainly control risk?
It can slightly help or slightly hurt returns depending on the period. The reliable benefit is risk control: keeping your equity share from drifting far away from target. Expecting rebalancing to boost returns is the wrong framing — it is a risk management tool first. For a practical rule set, see Rebalancing without stress.
Can I rebalance using only new contributions and withdrawals?
Often yes. Directing new money into underweight assets is soft rebalancing that can reduce trades, costs, and taxes. Platforms like Trade Republic savings plans or Trading 212 pies make this straightforward. You still need to check your actual weights at least once a year and correct if drift gets too large to manage through contributions alone.
Should I rebalance during a big crash or only on schedule?
With a calendar rule, waiting for the next scheduled rebalance is fine. With tolerance bands, a large move can trigger an earlier rebalance when allocations cross preset thresholds. The key is rules decided in advance — not improvisation during market stress. See the bands vs annual study for a direct comparison.
Does letting a portfolio drift really change the risk profile that much?
Yes, over long bull markets it can. After a decade-long equity rally, a 60/40 portfolio that was never rebalanced can easily drift to 80/20 or beyond without the investor noticing. That means significantly more downside exposure than the original plan intended — and the mismatch typically reveals itself exactly when markets correct sharply.
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