Portfolio rebalancing is the process of selling assets that have grown above your target allocation and buying assets that have fallen below. It is one of the simplest and most effective ways to manage risk and maintain your intended investment strategy over time.
What Is Rebalancing?
When you first build a portfolio, you choose a target allocation — for example, 60% stocks and 40% bonds. Over time, different assets grow at different rates. If stocks outperform bonds for a year, your portfolio might drift to 70% stocks and 30% bonds. You now hold more equity risk than you originally intended.
Rebalancing reverses this drift. You sell a portion of the assets that have become overweight and use the proceeds to buy assets that have become underweight. The result is a portfolio that matches your risk tolerance again.
Why Rebalance?
Without rebalancing, your portfolio gradually takes on more risk than you planned. Stocks historically outperform bonds over long periods, which means an unrebalanced stock-heavy portfolio becomes increasingly concentrated in equities. During a market downturn, this concentration magnifies your losses.
Rebalancing also enforces discipline. It forces you to sell what has gone up and buy what has gone down — a mechanical version of “buy low, sell high.” This is the opposite of what most investors do emotionally, which is chase recent winners and avoid recent losers.
When to Rebalance
Time-Based Rebalancing
The simplest approach is to rebalance on a fixed schedule — annually or semi-annually. Annual rebalancing is sufficient for most investors. It is easy to remember, keeps transaction costs low, and limits the number of taxable events you create.
Threshold-Based Rebalancing
A more precise method is to rebalance when any asset class drifts more than a set percentage — typically 5% — from its target. For example, if your target is 60% stocks and stocks reach 65% or drop to 55%, you rebalance.
Threshold rebalancing avoids unnecessary transactions when allocations remain close to target, but requires you to monitor your portfolio more frequently.
Which Approach Works Best?
For most Danish investors, annual rebalancing strikes the right balance between simplicity and effectiveness. Threshold rebalancing adds marginal benefit but increases complexity and monitoring overhead. If you prefer a set-and-forget approach, stick with annual.
How to Rebalance: Step by Step
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Determine your current allocation. Check the current value of each asset class in your portfolio. Calculate the percentage each represents of your total portfolio value.
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Compare to your target allocation. Identify which asset classes are overweight and which are underweight relative to your target.
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Calculate the difference. Determine how much you need to sell from overweight assets and how much you need to buy in underweight assets.
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Execute the trades. Sell the overweight assets first, then use the proceeds to buy underweight assets.
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Consider tax implications. Where possible, rebalance within tax-advantaged accounts first to avoid triggering a taxable event.
Tax-Efficient Rebalancing in Denmark
Selling assets to rebalance triggers a taxable event under the Danish shareholder model (aktionærmodel). Gains are taxed at 27% on the first DKK 61,000 and 42% above that for 2026. How you rebalance matters as much as when you rebalance.
Rebalancing in Tax-Advantaged Accounts First
- Aktiesparekonto — Rebalance here first. Gains are taxed at a flat 17% regardless of the amount. Selling to rebalance inside the aktiesparekonto is the most tax-efficient move.
- Pension accounts (ratepension, aldersopsparing) — Rebalance here next. Transactions within pension accounts do not create a current-year tax event. Growth is tax-deferred until withdrawal.
Rebalancing in Regular Accounts
If you must rebalance in a regular taxable account, follow these rules:
- Sell losers first (tax loss harvesting). If you have positions at a loss, selling them offsets gains elsewhere and reduces your tax bill.
- Sell winners within the 27% bracket. If you have not yet used your DKK 61,000 annual allowance at 27%, prioritise selling gains that fall within this lower bracket.
- Avoid selling large gains at 42%. If possible, rebalance by directing new investments to underweight assets instead of selling overweight ones.
Rebalancing with New Investments
Instead of selling overweight assets, you can rebalance by directing new contributions to underweight asset classes. This avoids triggering a taxable event entirely. If your stocks have grown to 70% and your bonds are at 30%, invest your next contribution entirely in bonds until you return to your target.
This approach works best when the drift is small and you have ongoing contributions. For large drifts, selling may be necessary.
Rebalancing Frequency
| Frequency | Pros | Cons |
|---|---|---|
| Monthly | Keeps allocation tight | High transaction costs, more tax events, no meaningful benefit over annual |
| Quarterly | Somewhat more precise than annual | Still more frequent than necessary for most investors |
| Annually | Simple, low costs, sufficient accuracy | May miss large mid-year drifts |
| Threshold-based | Only triggers when needed | Requires monitoring, may miss drifts if not checked regularly |
Annual rebalancing is the standard recommendation for long-term investors. More frequent rebalancing increases costs and taxes without meaningfully improving risk-adjusted returns. If you find yourself wanting to rebalance monthly, you are probably overthinking it.
Threshold Rebalancing in Practice
Suppose your target allocation is 60% stocks and 40% bonds. You set a 5% threshold band. You rebalance when:
- Stocks reach 65% or drop to 55%
- Bonds reach 45% or drop to 35%
This means you only trade when the drift is material enough to matter, rather than on every minor fluctuation. Check your portfolio quarterly or semi-annually and rebalance only when a threshold is breached.
Automatic Rebalancing
Some platforms offer automatic rebalancing. You set your target allocation, and the platform handles the rest — selling overweight assets and buying underweight ones on a schedule or when thresholds are breached.
- Nordnet — Offers automatic rebalancing through its monthly savings plans. You can set a target allocation and the platform adjusts contributions accordingly.
- Saxo Bank — Provides portfolio rebalancing tools for self-directed investors. You can set target weights and execute rebalancing trades manually or with guidance.
Automatic rebalancing removes the emotional component entirely. You set your targets, enable the feature, and let the platform maintain your allocation. For investors who struggle with discipline, this is the best option.
What NOT to Do
Don’t Rebalance Too Frequently
Each rebalancing trade creates costs — brokerage fees, bid-ask spreads, and potentially taxes. Monthly rebalancing can cost you more in friction than it saves in risk management. Annual is enough.
Don’t Rebalance During Market Panic
When markets crash 20-30%, your instinct may be to sell equities and move to bonds. This is the opposite of rebalancing — it is panic selling. Stick to your predetermined rebalancing schedule. If anything, a market crash is a reason to rebalance into equities, not out of them.
Don’t Forget to Consider Taxes
Every sale in a regular account is a taxable event. Selling a position with a DKK 100,000 gain to rebalance a 2% drift is not worth the DKK 42,000 tax bill. Factor taxes into your rebalancing decisions.
Don’t Chase Perfect Allocation
Your target allocation is a guideline, not a precise target. If your allocation is 58% stocks instead of 60%, that is close enough. Perfection is not the goal — risk management is.
Worked Example
You set up a portfolio with a target of 60% stocks and 40% bonds. Your total portfolio value is DKK 500,000.
After one year:
| Asset Class | Starting Value | Target Allocation | Target Value | Current Value | Current % |
|---|---|---|---|---|---|
| Stocks | DKK 300,000 | 60% | DKK 300,000 | DKK 350,000 | 70% |
| Bonds | DKK 200,000 | 40% | DKK 200,000 | DKK 150,000 | 30% |
| Total | DKK 500,000 | 100% | DKK 500,000 | DKK 500,000 | 100% |
Stocks have grown to 70%, bonds have dropped to 30%. Your portfolio is riskier than intended.
Rebalancing trades:
- Sell DKK 50,000 of stocks (reduce from DKK 350,000 to DKK 300,000)
- Buy DKK 50,000 of bonds (increase from DKK 150,000 to DKK 200,000)
After rebalancing:
| Asset Class | Value | % of Portfolio |
|---|---|---|
| Stocks | DKK 300,000 | 60% |
| Bonds | DKK 200,000 | 40% |
Your portfolio is back to 60/40. Your risk level is restored. If stocks continue to rise, you will sell again at your next rebalancing date. If stocks fall, your bond allocation cushions the decline.
Rebalancing with New Investments
If you contribute DKK 10,000 per month to your portfolio, you can rebalance without selling by directing new contributions to underweight assets.
Using the same example above, instead of selling DKK 50,000 of stocks, you could invest your next five months of contributions entirely in bonds. After five months of DKK 10,000 monthly contributions to bonds:
- Stocks: DKK 350,000 (64.8%)
- Bonds: DKK 200,000 (37%)
- New bond contributions: DKK 50,000
Your allocation moves closer to target without triggering any taxable events. This is the most tax-efficient rebalancing method for investors with regular contributions.
Practical Tips
- Set a calendar reminder. Pick a date — January 1st or your birthday — and rebalance once a year. Write it in your calendar and stick to it.
- Use tax-advantaged accounts first. Rebalance inside your aktiesparekonto and pension before touching your regular account.
- Don’t overthink it. Annual rebalancing with a simple 60/40 or 70/30 allocation is sufficient for most investors. Complex strategies add complexity without proportional benefit.
- Keep records. Track your rebalancing trades for tax reporting purposes. Your broker will report transactions to SKAT, but keeping your own records ensures accuracy.
- Automate where possible. If your broker offers automatic rebalancing, use it. Removing yourself from the decision is almost always better.
Conclusion
Portfolio rebalancing is not a sophisticated technique — it is a maintenance task. Like servicing your car or filing your taxes, it is something you do periodically to keep things running smoothly. Set your target allocation, rebalance once a year, prioritise tax-advantaged accounts, and resist the urge to do more. The investors who earn the best returns are usually the ones who do the least.