Rebalancing is the process of restoring a portfolio to a previously defined target asset allocation after market movements cause asset weights to drift. By selling assets that have grown to become a larger share of the portfolio and buying those that have lagged, rebalancing helps keep the portfolio aligned with the investor’s risk tolerance and financial goals.
Why it matters
– Keeps risk exposure consistent with your plan (e.g., a 60/40 stocks/bonds portfolio remains near that risk profile).
– Forces a systematic “sell high, buy low” discipline rather than emotional trading.
– Helps keep the portfolio within the manager’s area of expertise.
– Allows adjusting allocations when goals or circumstances change (e.g., nearing retirement).
Core rebalancing strategies
1. Calendar rebalancing
– Review and rebalance at set intervals (annually, semiannually, quarterly).
– Pros: simple, predictable, low administrative burden.
– Cons: may miss big market moves between dates.
2. Threshold (constant-mix) rebalancing (bands/corridors)
– Specify target weights and tolerance bands (e.g., 60% stocks ±5%). Rebalance only when an asset class moves outside its band.
– Pros: more responsive to market drift, potentially fewer unnecessary trades.
– Cons: requires monitoring and a decision rule for when to rebalance.
3. Constant Proportion Portfolio Insurance (CPPI)
– A “floor” is set for portfolio value; allocation to risky assets is determined by the cushion (portfolio value minus floor) multiplied by a multiplier.
– Pros: dynamic exposure control; protects a portfolio floor.
– Cons: more complex and can lead to rapid shifts in allocation during volatile markets.
4. Smart-beta / rules-based rebalancing
– Apply systematic rules (value, quality, low-volatility, etc.) to select and weight holdings; rebalanced periodically to those rules.
– Pros: removes emotion, seeks systematic factor exposures.
– Cons: more active than market-cap indexing and depends on the chosen rules.
Costs and tradeoffs
– Transaction costs: commissions, bid-ask spreads, execution slippage.
– Taxes: realizing gains in taxable accounts can trigger capital gains tax.
– Opportunity cost: rebalancing away from winners may limit upside if a trend continues.
– Timing and effort: more frequent or active strategies require monitoring and may increase costs.
Practical steps to rebalance (step-by-step)
1. Define your target allocation and rationale
• Example: 60% equities / 40% bonds based on risk tolerance and goals. Document this in an investment policy or plan.
2. Choose a rebalancing method and frequency
• Calendar (e.g., annual), threshold-based (e.g., ±5% bands), or hybrid.
3. Measure current allocation
• Add up current market values by asset class and compute weights (current value of asset / total portfolio value).
4. Decide whether rebalancing is needed
• If using calendar, rebalance on the scheduled date.
• If using bands, rebalance only if any allocation is outside its band.
5. Calculate trades required to return to target
• Example calculation: $100,000 portfolio, 60/40 target. If equities grow to $75,000 (75%) and bonds fall to $25,000 (25%), sell $15,000 of equities and buy $15,000 of bonds to return to 60/40.
6. Minimize costs and tax impact
• Use new contributions/dividends to buy underweight assets rather than selling winners.
• Rebalance inside tax-advantaged accounts first (IRA, 401(k)) to avoid taxes.
• If selling in taxable accounts, consider tax-loss harvesting or selling lots with higher cost basis to reduce gains.
7. Execute trades and document
• Keep records of dates, rationale, and transactions. This supports discipline and later review.
8. Monitor and review
• Reassess allocation and the rebalancing rules periodically. Update target allocation if life goals or risk tolerance change.
Practical examples
– Simple numeric example (annual rebalance): Start $100,000 with 60/40 (stocks $60k / bonds $40k). After a bull run, stocks = $75k, bonds = $25k. Rebalance by selling $15k stocks and buying $15k bonds to restore 60/40.
– Threshold example: Same 60/40 target with ±5% band (stocks 55–65%). If equities hit 67%, the band is breached and you rebalance back to 60%.
– Using contributions: If you don’t want to sell winners in a taxable account, direct ongoing contributions to the underweight asset (bonds) until allocation is back in range.
Rebalancing retirement accounts
– Prefer rebalancing within tax-advantaged accounts first to avoid taxable events.
– Target-date funds offer automatic glide paths (become more conservative over time); use them if you want a hands-off approach.
– As you near retirement, shift to more conservative allocations (documented in your plan) and rebalance to maintain that lower-risk posture.
Rebalancing for diversification
– Rebalancing enforces diversification by preventing any one asset class from dominating the portfolio.
– A target allocation need not be 50/50; it should reflect your objectives (e.g., 70/30, 40/60, or multi-asset mixes including cash, equities, bonds).
How often should you rebalance?
– No single correct answer. Common practices: annually, semiannually, or when an asset class moves outside a tolerance band (e.g., ±5–10%).
– Consider time, transaction costs, tax considerations, and how much drift you accept in your risk exposure. Many advisors recommend at least an annual check.
Pros and cons (summary)
Pros
– Keeps risk consistent with plan.
– Disciplined approach to taking profits and buying underweights.
– Prevents concentration risk and maintains manager expertise boundaries.
Cons
– Trading costs and potential taxes.
– Can limit upside if you repeatedly sell the best performers.
– Requires discipline and monitoring; more active methods add complexity.
Checklist for a rebalance event
– Confirm target allocation and rebalancing rules.
– Calculate current weights and required trades.
– Decide whether to use contributions/dividends to rebalance.
– Evaluate tax consequences and trading costs.
– Execute trades (preferably in tax-advantaged accounts first).
– Record and review the action and rationale.
Bottom line
Rebalancing is a foundational portfolio-management discipline that maintains alignment between your investments and your financial goals. The right approach depends on your time horizon, tax situation, transaction-cost tolerance, and willingness to monitor the portfolio. Whether using simple annual rebalances, threshold bands, or more sophisticated dynamic strategies, the key is to have a documented plan and follow it consistently.
Source
Adapted and summarized from Investopedia — “Rebalancing” .