Asset allocation optimizer • 2026 portfolio tool
The rebalancing calculation is: Target Value = Total Portfolio Value × Target Allocation %
For each asset, calculate:
Example: If total portfolio is $100,000 with 60% target allocation to stocks, the target value should be $60,000. If current value is $70,000, the deviation is +10%, requiring a $10,000 reduction.
| Asset | Target % | Current % | Deviation | Target Value | Current Value | Adjustment |
|---|---|---|---|---|---|---|
| US Stocks | 60.0% | 70.0% | +10.0% | $60,000.00 | $70,000.00 | Sell $10,000.00 |
| Intl Stocks | 20.0% | 15.0% | -5.0% | $20,000.00 | $15,000.00 | Buy $5,000.00 |
| Bonds | 15.0% | 12.0% | -3.0% | $15,000.00 | $12,000.00 | Buy $3,000.00 |
| Cash | 5.0% | 3.0% | -2.0% | $5,000.00 | $3,000.00 | Buy $2,000.00 |
| Action | Asset | Amount | Reason |
|---|---|---|---|
| Sell | US Stocks | $10,000.00 | Overweight by 10% |
| Buy | Intl Stocks | $5,000.00 | Underweight by 5% |
| Buy | Bonds | $3,000.00 | Underweight by 3% |
| Buy | Cash | $2,000.00 | Underweight by 2% |
Portfolio rebalancing is the process of realigning the weight of assets in an investment portfolio. Over time, different assets perform differently, causing the portfolio to drift from its original allocation. Rebalancing brings the portfolio back to its target allocation, maintaining the desired risk profile and investment strategy.
Key rebalancing metrics are calculated using these formulas:
Where:
Key metrics for evaluating rebalancing effectiveness:
The process of realigning portfolio asset weights to maintain target allocation.
\( \text{Adjustment} = \text{Target Value} - \text{Current Value} \)
Where target value is portfolio value × target allocation.
Measure how much current allocation differs from target allocation.
If a portfolio has a target allocation of 60% stocks and 40% bonds, but the current allocation is 70% stocks and 30% bonds due to market movements, what should be done to rebalance?
The answer is B) Sell stocks and buy bonds. The portfolio is overweight in stocks (70% vs. 60% target) and underweight in bonds (30% vs. 40% target). To rebalance, you need to sell 10% of the portfolio's value in stocks and use those proceeds to buy bonds, bringing both allocations back to their target levels.
Rebalancing always moves assets from overweights to underweights. In this example, stocks have appreciated beyond their target allocation, while bonds have fallen below theirs. The correction involves selling the winning asset class (stocks) and buying the losing one (bonds) to restore the original risk profile. This contrarian approach helps maintain the intended risk-return characteristics of the portfolio.
Overweight: Asset allocation above target percentage
Underweight: Asset allocation below target percentage
Target Allocation: Desired percentage for each asset class
• Always move from overweights to underweights
• Maintain total portfolio value during rebalancing
• Consider transaction costs and taxes
• Use the formula: Deviation = Current % - Target %
• Positive deviation means sell, negative means buy
• Consider using new contributions for rebalancing
• Adding to overweights instead of underweights
• Forgetting to consider transaction costs
• Not rebalancing when needed
A $200,000 portfolio has a target allocation of 60% stocks and 40% bonds. Due to market performance, the current allocation is 75% stocks and 25% bonds. Calculate the target values, current values, deviations, and the amount needed to rebalance each asset class.
Calculations:
Target Value for Stocks: $200,000 × 60% = $120,000
Target Value for Bonds: $200,000 × 40% = $80,000
Current Value for Stocks: $200,000 × 75% = $150,000
Current Value for Bonds: $200,000 × 25% = $50,000
Deviation for Stocks: 75% - 60% = +15%
Deviation for Bonds: 25% - 40% = -15%
Adjustment for Stocks: $120,000 - $150,000 = -$30,000 (sell $30,000)
Adjustment for Bonds: $80,000 - $50,000 = +$30,000 (buy $30,000)
Conclusion: Sell $30,000 of stocks and buy $30,000 of bonds to rebalance the portfolio.
This calculation demonstrates the systematic approach to portfolio rebalancing. The process involves three steps: calculating target values based on desired allocation, determining current values, and finding the difference to determine required actions. The key insight is that the adjustment amount is equal for both assets but opposite in direction. This ensures the portfolio maintains its total value while achieving the target allocation.
Target Value: Dollar amount each asset should represent
Current Value: Actual market value of each asset
Deviation: Difference between current and target allocation
• Total portfolio value remains unchanged during rebalancing
• Use the formula: Target Value = Total × Target %
• Calculate deviation as Current % - Target %
• Adjustment = Target Value - Current Value
• Calculating percentages incorrectly
• Forgetting to convert percentages to dollar amounts
• Not considering the impact of rebalancing on total value
Q: How often should I rebalance my portfolio, and what's the optimal threshold for triggering rebalancing?
A: The optimal rebalancing frequency depends on your portfolio size, transaction costs, and tax situation. Common approaches include:
Calendar-Based: Quarterly or annually for simplicity
Threshold-Based: When allocations deviate by 5% or more from targets
Hybrid Approach: Annual rebalancing or when thresholds are exceeded, whichever comes first
The formula for determining the optimal threshold considers transaction costs:
Optimal Threshold = √(2 × Transaction Cost × Expected Return / (Volatility² × ln(1 + Target Return)))
For most retail investors, a 5% threshold with annual rebalancing strikes a good balance between maintaining target allocations and minimizing costs. With higher transaction costs or lower expected returns, wider thresholds (7-10%) may be more appropriate.
Q: How do taxes affect rebalancing decisions in taxable accounts?
A: Tax implications significantly affect rebalancing strategies in taxable accounts. When selling appreciated assets, you trigger capital gains taxes:
Tax Cost = (Sale Value - Cost Basis) × Tax Rate
Tax-Efficient Rebalancing Strategies:
Consider the after-tax cost of rebalancing: If the tax cost of rebalancing exceeds the expected benefit of maintaining target allocation, it may be better to delay rebalancing. For example, if rebalancing would trigger $2,000 in taxes but only provide $1,500 in expected benefits, it's better to wait.