Rebalancing is the process of realigning the weightings of your portfolio back to your target asset allocation. It is one of the most important — and most often neglected — maintenance tasks in long-term investing. Done correctly, it enforces the discipline of buying low and selling high automatically.
What Is Portfolio Rebalancing?
When you first build an investment portfolio, you allocate your capital across different asset classes — stocks, bonds, cash, real estate, or specific sectors — in proportions that reflect your risk tolerance and investment goals. This is your target allocation.
Over time, as different assets grow at different rates, your actual allocation will drift away from your target. If you started with 60% stocks and 40% bonds, and stocks outperform bonds for two years, you might find yourself at 72% stocks and 28% bonds. You are now carrying more risk than you originally intended — and more than your plan called for.
Rebalancing corrects this drift by selling portions of assets that have grown above their target weight and using the proceeds to buy assets that have fallen below their target weight. The result: you are systematically selling what has gone up and buying what has gone down — a form of disciplined, unemotional contrarian investing built into your maintenance process.
Why Rebalancing Matters
The primary purpose of rebalancing is risk control, not return maximisation. A portfolio that is never rebalanced will naturally drift toward its highest-performing assets over time — which means it will also drift toward whatever is currently most expensive and most volatile. Without rebalancing, a conservative investor can inadvertently become an aggressive one simply through market drift.
The secondary benefit is the mechanical buy-low-sell-high discipline it imposes. Rebalancing forces you to add to underperforming asset classes when they feel uncomfortable to own and trim outperformers at their peaks — the opposite of what most investors naturally want to do.
Studies on rebalancing show that while it does not always improve raw returns (sometimes a drifting portfolio outperforms), it consistently reduces volatility and maximum drawdown over full market cycles — which means better risk-adjusted returns and a smoother investor experience.
How Often Should You Rebalance?
There are two main approaches to deciding when to rebalance: calendar-based and threshold-based.
| Approach | Method | Best For | Drawback |
|---|---|---|---|
| Calendar Rebalancing | Rebalance on a fixed schedule (quarterly, semi-annually, annually) | Simple portfolios, passive investors | May rebalance when drift is minimal; misses large mid-period drifts |
| Threshold Rebalancing | Rebalance when any asset class drifts beyond a set band (e.g. ±5%) | More precise risk control | Requires more monitoring; may trigger more frequently in volatile markets |
| Hybrid Approach | Check quarterly; rebalance only if drift exceeds threshold | Most investors | Slightly more complexity |
For most long-term retail investors, an annual or semi-annual review with a 5% drift threshold is a sensible and practical approach. Rebalancing more frequently than quarterly is generally not necessary and can create excessive transaction costs and tax events.
Tax-Smart Rebalancing
In taxable accounts, selling appreciated assets to rebalance triggers capital gains tax. There are several strategies to minimise this friction.
- Rebalance through new contributions: Rather than selling overweight positions, direct new money into underweight asset classes. This corrects drift without triggering sales.
- Rebalance in tax-sheltered accounts first: Do your selling and buying within your TFSA, RRSP, Roth IRA, or 401(k) where gains are not immediately taxable.
- Use dividends strategically: Redirect dividend income from overweight holdings toward underweight positions rather than reinvesting automatically.
- Tax-loss harvesting: If any holdings are at a loss, selling them to offset gains elsewhere reduces the net tax cost of rebalancing.
Rebalancing Across Canadian, U.S., and Indian Markets
If you hold investments across multiple markets — a common situation for the globally-minded retail investor — rebalancing must also account for currency exposure, withholding tax on foreign dividends, and the different market cycles that different jurisdictions may be experiencing simultaneously.
A Canadian investor holding both TSX and U.S. equity ETFs, for example, needs to consider whether to rebalance the currency exposure as well as the equity weighting. Using currency-hedged ETFs simplifies this decision but comes with its own cost and tracking error considerations.
Conclusion
Rebalancing is not exciting — but it is one of the most reliably beneficial maintenance habits an investor can build. It keeps your risk level consistent with your plan, enforces discipline during both bull and bear markets, and prevents the dangerous drift toward excessive risk that can occur in long, sustained rallies. Build a rebalancing review into your calendar at least once a year, set clear drift thresholds, and execute it as a mechanical process rather than an emotional one.
A Practical Rebalancing Example
Suppose you began 2024 with a $100,000 portfolio allocated 60% equities ($60,000) and 40% bonds ($40,000). By year end, strong equity markets have pushed your equities to $82,000 while bonds grew modestly to $43,000 — a total portfolio of $125,000. Your new allocation is 65.6% equities and 34.4% bonds, well outside your 5% drift threshold.
To rebalance back to 60/40, you would sell approximately $6,900 of equities and buy $6,900 of bonds, restoring your target weights. In a tax-sheltered account like a TFSA or Roth IRA, this transaction has no immediate tax consequence. In a taxable account, the equity sale generates a taxable capital gain on the $6,900 sold — a cost worth bearing to maintain your intended risk profile.
Rebalancing vs. Simply Buying More
For investors in the accumulation phase who are making regular contributions, rebalancing through new purchases — rather than selling overweight positions — is often the most tax-efficient approach. If equities are overweight, simply direct your next monthly contribution entirely to bonds until the balance is restored. This achieves the same result without triggering any taxable sales, preserving more capital for long-term compounding.
This approach has limits: in a strongly trending market, new contributions alone may be insufficient to rebalance a large, rapidly drifting portfolio. In those cases, some selling of overweight positions is unavoidable — and should be executed anyway, because maintaining your target risk level is worth the cost.
The Emotional Challenge of Rebalancing
Rebalancing forces investors to do something deeply counterintuitive: sell the assets that have recently performed best and add to those that have underperformed. This runs directly against the psychological pull of recent performance — our natural instinct is to want more of whatever has been working and less of whatever has not.
During a strong bull market in equities, rebalancing into bonds feels like leaving money on the table. During a sharp market correction, adding to equities feels terrifying. These are precisely the moments when the discipline of a rules-based rebalancing process is most valuable — and most difficult to execute. Having a written plan and a fixed schedule removes the decision from the emotional moment and places it in a calmer, more rational context.