Investment Rebalancing: Keeping Your Portfolio From Drifting Off Target
Why a Singapore investor’s original 60/40 or 70/30 asset mix rarely stays that way without periodic adjustment — and how to rebalance without overtrading.
Investment rebalancing is the periodic process of buying and selling portions of a portfolio to restore it to its originally intended asset allocation, correcting the natural drift that occurs when different asset classes grow at different rates over time.
Not financial advice. All figures for educational reference only. Data as at September 2026. Last updated: September 2026.
Key Takeaways
- A portfolio that starts at a 60% equities/40% bonds split can drift to 70/30 or further after a strong equity market run, quietly taking on more risk than originally intended.
- The two most common rebalancing approaches are calendar-based (fixed schedule, e.g. annually) and threshold-based (rebalance only when an allocation drifts beyond a set percentage, e.g. 5%).
- Singapore investors using CPF Investment Scheme or SRS funds should factor in the more limited fund choices and transaction costs when deciding how often to rebalance within those accounts.
- Rebalancing by directing new contributions toward underweight assets, rather than selling overweight ones, can reduce transaction costs and avoid triggering capital gains where relevant.
- Over-rebalancing (too frequently) can erode returns through transaction costs and taxes, while under-rebalancing lets risk drift further from the investor’s original comfort level.
Table of Contents
What Is Investment Rebalancing?
How Rebalancing Works in Singapore
Example
Advantages
Risks and Limitations
Calendar-Based vs Threshold-Based Rebalancing
The Bottom Line
FAQ
What Is Investment Rebalancing?
When a Singapore investor first builds a portfolio — say, a 60% equities and 40% bonds split, or a mix across ETFs, S-REITs, and cash — that allocation reflects a deliberate risk tolerance and investment goal at the time. Over months and years, different asset classes grow at different rates: equities might rally strongly while bonds lag, or vice versa during a downturn. Without any action, the portfolio’s actual weights drift away from the original target purely due to differing returns, not because the investor made any new decision.
Rebalancing is the discipline of periodically buying and selling to bring the portfolio back to its intended allocation. If equities have grown to represent 70% of the portfolio (up from an original 60% target), rebalancing means selling some equities and buying bonds (or directing new money into bonds) to bring the mix back toward 60/40.
This matters because portfolio drift is really a form of unintentional risk-taking. An investor who never rebalances after a multi-year bull market may find their portfolio is significantly riskier than they originally signed up for, right before a downturn — the exact wrong time to discover it.
How Does Investment Rebalancing Work in Singapore?
Singapore investors typically use one of two rebalancing approaches, sometimes combined:
1. Calendar-based rebalancing. The investor reviews and rebalances the portfolio on a fixed schedule — commonly annually, semi-annually, or quarterly — regardless of how far the allocation has drifted. This is simple and easy to stick to.
2. Threshold-based rebalancing. The investor sets a drift tolerance, for example 5 percentage points, and only rebalances when an asset class’s actual weight moves beyond that band from its target. This responds more precisely to market moves but requires more frequent monitoring.
3. Rebalancing with new contributions. Rather than selling overweight assets (which can trigger transaction costs or, in taxable jurisdictions, capital gains tax — less relevant in Singapore’s no-capital-gains-tax environment for individual investors, but still relevant for transaction fees), an investor can direct new monthly or periodic contributions disproportionately toward underweight asset classes until the target allocation is restored.
4. Within CPF and SRS accounts. Singapore investors using the CPF Investment Scheme or Supplementary Retirement Scheme to hold unit trusts or ETFs should factor in the more limited fund menu and any sales charges when rebalancing within these accounts, since frequent trading can be costlier than in a standard brokerage account.
Investors holding assets across several account types — a CDP-linked brokerage account, a CPF Investment Scheme account, an SRS account, and perhaps a robo-advisor portfolio — should ideally think of rebalancing at the total household portfolio level rather than treating each account in isolation, since an allocation that looks balanced within one account may look quite different once every holding is combined into a single overall view.
Investment Rebalancing Example
A Singapore investor starts with S$100,000 split 60% into a global equity ETF (S$60,000) and 40% into a bond fund (S$40,000). After two strong years for equities, the equity portion grows to S$85,000 while the bond portion grows modestly to S$42,000, for a total of S$127,000 — equities now represent about 67% of the portfolio, a meaningful drift from the original 60% target.
To rebalance, the investor sells approximately S$8,800 worth of the equity ETF and uses the proceeds to buy the bond fund, restoring the split to roughly 60% equities (S$76,200) and 40% bonds (S$50,800). Alternatively, if the investor is still making monthly contributions, they could redirect a larger share of new money into the bond fund over the following months to achieve the same rebalancing effect without selling any existing equity holdings.
Advantages of Investment Rebalancing
Keeps risk aligned with your original tolerance. Rebalancing prevents a portfolio from silently becoming riskier (or more conservative) than intended purely due to market movements.
Enforces a disciplined buy-low, sell-high habit. Rebalancing mechanically involves trimming what has grown and adding to what has lagged, which is the opposite of an emotional, performance-chasing instinct.
Can be done without selling, via new contributions. Directing fresh money toward underweight assets achieves the same effect as selling and buying, often with lower transaction costs.
Straightforward to automate for many Singapore investors. Some robo-advisors and platforms popular in Singapore offer automatic rebalancing as a built-in feature, removing the need for manual tracking.
Risks and Limitations
Transaction costs can erode the benefit. Frequent rebalancing, especially with small drift thresholds, can rack up brokerage fees or fund sales charges that offset the risk-management benefit.
Rebalancing too rigidly can cut short a winning trend. Trimming an overweight asset that continues to outperform means giving up some further gains in exchange for risk control — a trade-off, not a free lunch.
Requires ongoing attention or automation. Investors who set a portfolio and never revisit it will experience uncontrolled drift; rebalancing requires either periodic manual review or an automated system.
CPF/SRS fund limitations. Rebalancing within CPF Investment Scheme or SRS accounts is constrained by the available fund menu, which may not perfectly match the investor’s broader brokerage account allocation.
Calendar-Based vs Threshold-Based Rebalancing
Each method trades off simplicity against responsiveness to market moves.
| Factor | Calendar-Based | Threshold-Based |
|---|---|---|
| Trigger | Fixed schedule (e.g. annually) | Allocation drifts beyond set % band |
| Simplicity | Very simple, easy to stick to | Requires ongoing monitoring |
| Responsiveness | Can miss large mid-period moves | Reacts closer to when drift actually occurs |
| Transaction frequency | Predictable, usually low | Variable, depends on market volatility |
Source: General portfolio management practice, illustrative.
Common Mistakes to Avoid
Rebalancing based on emotion rather than a set rule. Selling winners during a market panic or refusing to trim a hot-performing asset out of attachment both defeat the purpose of a disciplined rebalancing rule.
Ignoring transaction costs and fund sales charges. Rebalancing very small drifts too frequently, especially within CPF Investment Scheme or SRS funds that may carry sales charges, can quietly erode returns over time.
Forgetting to include all accounts in the rebalancing view. An investor who rebalances their brokerage account but forgets their CPF-invested or SRS-invested holdings may still end up with an unintended overall risk level once every account is considered together.
The Bottom Line
Rebalancing is a simple, low-cost discipline that keeps a Singapore investor’s portfolio risk aligned with their original plan rather than whatever the market has drifted it toward. Whether using a calendar or threshold approach, the key is picking one method and sticking to it consistently, rather than rebalancing reactively based on market emotion.