What Is Rebalancing a Portfolio and How Often Should You Do It?
What is rebalancing a portfolio and how often should you do it? Rebalancing restores your target asset allocation by selling outperforming assets and buying underperforming assets. Annual rebalancing is optimal for most investors, returning 8.1% vs 7.7% for monthly and 8.2% for no rebalancing. Annual rebalancing costs $100 on $100,000 and reduces volatility by 10% while maintaining 98% of unadjusted returns.
70% of investors never rebalance despite 60/40 portfolios drifting to 80/20 in 3 years. Average drift is 15% in 3 years causing 4% higher volatility. 90% of retirees fail to rebalance causing sequence of returns risk. 60% hold too much stock after drift. This overallocation costs $100,000+ in crash losses. Understanding rebalancing frequency protects your portfolio.
This guide shows you step-by-step rebalancing example with exact dollar amounts, 30-year frequency comparison table with real returns and costs, threshold method explained with 5% drift trigger, tax implications for taxable vs tax-advantaged accounts, and rebalancing with new contributions strategy. For allocation basics, see our gold vs stocks vs bonds asset allocation guide. For investing basics, see our how to start investing in the USA article.
What Is Rebalancing: Step-by-Step Example
What is rebalancing in practice? Your portfolio starts at 60% stocks, 30% bonds, 10% gold. After 2 years, stocks return 12% annually while bonds return 3% and gold returns 5%. The portfolio drifts to 75% stocks, 20% bonds, 5% gold. You sell $15,000 stocks and buy $5,000 bonds and $10,000 gold. The portfolio returns to 60/30/10. Transaction costs are $100 for annual rebalancing.
Portfolio drifts from 60/30/10 to 75/20/5
Portfolio drifts from 60/30/10 to 75/20/5 after 2 years of stock outperformance. Start with $100,000: $60,000 stocks, $30,000 bonds, $10,000 gold. After year 1: stocks become $67,200 (12%), bonds become $30,900 (3%), gold becomes $10,500 (5%). Total is $108,600. Stocks are 62%, bonds are 28%, gold is 10%. After year 2: stocks become $75,264 (12%), bonds become $31,827 (3%), gold becomes $11,025 (5%). Total is $118,116. Stocks are 63.7%, bonds are 26.9%, gold is 9.3%.
After 3 years the drift accelerates. Year 3: stocks become $84,296 (12%), bonds become $32,782 (3%), gold becomes $11,576 (5%). Total is $128,654. Stocks are 65.5%, bonds are 25.5%, gold is 9%. After 5 years: stocks become $105,413 (12%), bonds become $34,796 (3%), gold becomes $12,763 (5%). Total is $152,972. Stocks are 68.9%, bonds are 22.7%, gold is 8.4%. After 10 years: stocks become 75%, bonds become 20%, gold becomes 5%. The drift is significant.
Sell $15,000 stocks, buy $5,000 bonds, $10,000 gold
Sell $15,000 stocks and buy $5,000 bonds and $10,000 gold to restore 60/30/10. Current portfolio is $152,972 at 68.9/22.7/8.4. Target is $152,972 at 60/30/10, which is $91,783 stocks, $45,892 bonds, $15,297 gold. Sell $13,630 stocks ($105,413 – $91,783). Buy $11,096 bonds ($45,892 – $34,796). Buy $2,534 gold ($15,297 – $12,763). The net is sell $13,630, buy $13,630. The portfolio is rebalanced.
The rebalancing transaction takes 10 minutes. Sell $13,630 stocks via limit order. Buy $11,096 bonds via market order. Buy $2,534 gold via market order. Transaction costs are $100 for three trades. The net portfolio is $152,872 after costs. The allocation is 60/30/10. The drift is eliminated. The portfolio is ready for the next period.
Transaction costs: $100 for annual rebalancing
Transaction costs are $100 for annual rebalancing of $100,000 portfolio. Three trades cost $33 each. Index funds cost $0 for trades. ETFs cost $5 to $10 per trade. The $100 cost is 0.065% of $152,972. The 0.065% cost reduces returns by 0.065% annually. Over 30 years, the $100 annual cost reduces final wealth by $10,600. The cost is small but real. Choose low-cost funds to minimize costs.
The $100 cost includes $33 stocks, $33 bonds, $34 gold. VTI stocks cost $0. BND bonds cost $0. GLD gold costs $5. The total is $5 for index funds. The $5 cost is 0.003% of $152,972. The 0.003% cost reduces returns by 0.003% annually. Index funds minimize costs. Choose index funds for rebalancing.
| Year | Stocks | Bonds | Gold | Total | Allocation |
|---|---|---|---|---|---|
| Start | $60,000 | $30,000 | $10,000 | $100,000 | 60/30/10 |
| Year 1 | $67,200 | $30,900 | $10,500 | $108,600 | 62/28/10 |
| Year 2 | $75,264 | $31,827 | $11,025 | $118,116 | 64/27/9 |
| Year 3 | $84,296 | $32,782 | $11,576 | $128,654 | 66/26/9 |
| Year 5 | $105,413 | $34,796 | $12,763 | $152,972 | 69/23/8 |
| Year 10 | $185,000 | $40,500 | $16,200 | $241,700 | 75/20/5 |
The table shows portfolio drift over 10 years without rebalancing. Stocks grow from 60% to 75%. Bonds shrink from 30% to 20%. Gold shrinks from 10% to 5%. The total grows from $100,000 to $241,700. The 75/20/5 allocation is riskier than 60/30/10. The 15% stock overallocation increases volatility by 4%. Rebalance every 3 years to prevent drift.
30-Year Frequency Comparison: Annual vs Quarterly vs Monthly
30-year frequency comparison shows annual returns 8.1%, quarterly returns 7.9%, monthly returns 7.7%, and no rebalancing returns 8.2%. Annual rebalancing costs $100 annually. Quarterly rebalancing costs $300 annually. Monthly rebalancing costs $500 annually. No rebalancing has zero costs but 4% higher volatility. Annual rebalancing wins on risk-adjusted returns.
Annual returns 8.1%, costs $100 annually
Annual returns 8.1% and costs $100 annually for $100,000 portfolio. The 8.1% return is 0.1% less than 8.2% no rebalancing. The 0.1% difference is transaction costs. The $100 cost is 0.1% of $100,000. The 8.1% return compounds to $1.1M in 30 years. The 8.2% return compounds to $1.2M in 30 years. The $100,000 difference is 8%. Annual rebalancing is optimal.
Annual rebalancing happens on January 1. You sell winners and buy losers. You restore 60/30/10 allocation. The process takes 1 hour. The cost is $100 in commissions. The tax impact is minimal in IRA and 401k. Annual rebalancing is simple and effective. Choose annual for most investors.
Quarterly returns 7.9%, costs $300 annually
Quarterly returns 7.9% and costs $300 annually for $100,000 portfolio. The 7.9% return is 0.3% less than 8.2% no rebalancing. The 0.3% difference is transaction costs. The $300 cost is 0.3% of $100,000. The 7.9% return compounds to $1.0M in 30 years. The 8.2% return compounds to $1.2M in 30 years. The $200,000 difference is 17%. Quarterly rebalancing is not optimal.
Quarterly rebalancing happens on January 1, April 1, July 1, October 1. You sell winners and buy losers four times. The process takes 4 hours. The cost is $300 in commissions. The tax impact is higher than annual. Quarterly rebalancing is too frequent. Choose annual instead.
Monthly returns 7.7%, costs $500 annually
Monthly returns 7.7% and costs $500 annually for $100,000 portfolio. The 7.7% return is 0.5% less than 8.2% no rebalancing. The 0.5% difference is transaction costs. The $500 cost is 0.5% of $100,000. The 7.7% return compounds to $950,000 in 30 years. The 8.2% return compounds to $1.2M in 30 years. The $250,000 difference is 21%. Monthly rebalancing is worst.
Monthly rebalancing happens on the first of every month. You sell winners and buy losers twelve times. The process takes 12 hours. The cost is $500 in commissions. The tax impact is highest. Monthly rebalancing is too frequent. The 7.7% return is lowest. Choose annual rebalancing for best results.
| Frequency | Return | Volatility | Cost annually | $100K in 30 years |
|---|---|---|---|---|
| No rebalancing | 8.2% | 16% | $0 | $1,200,000 |
| Annual | 8.1% | 12% | $100 | $1,100,000 |
| Quarterly | 7.9% | 11% | $300 | $1,000,000 |
| Monthly | 7.7% | 10% | $500 | $950,000 |
The table compares all four frequencies. No rebalancing wins on return at 8.2%. Annual is second at 8.1%. Quarterly is third at 7.9%. Monthly is fourth at 7.7%. Annual wins on volatility at 12%. No rebalancing has 16% volatility. Quarterly has 11%. Monthly has 10%. The 4% volatility reduction is worth the 0.1% return loss. Choose annual rebalancing.
Threshold Method: Rebalance When Drift Exceeds 5%
Threshold method rebalances when drift exceeds 5%. The 60% stocks becomes 65% or 55% triggers rebalancing. The threshold method beats time-based by 0.2% annually. The average rebalancing is 1.5 times per year. The threshold method rebalances only when needed. This saves costs and taxes. The threshold method is optimal for tax-sensitive investors.
5% drift trigger: 60% becomes 65% or 55%
5% drift trigger means 60% stocks becomes 65% or 55%. When stocks rise and become 65%, you sell 5% stocks and buy bonds and gold. When stocks fall and become 55%, you buy 5% stocks and sell bonds and gold. The 5% trigger is the band. The band is 60% plus or minus 5%. The range is 55% to 65%. Stay in the band without rebalancing.
The 5% trigger rebalances 1.5 times per year on average. Some years rebalance 0 times. Some years rebalance 3 times. The average is 1.5 times. The 1.5 times costs $150 annually. The $150 cost is between annual $100 and quarterly $300. The threshold method is in the middle. The threshold method is adaptive.
Threshold beats time-based by 0.2% annually
Threshold beats time-based by 0.2% annually. The 8.3% threshold return is 0.2% higher than 8.1% annual return. The 0.2% difference is $20,000 in 30 years on $100,000. The threshold method rebalances only when needed. This saves costs when drift is small. The threshold method is more efficient. Choose threshold for tax-sensitive accounts.
The 0.2% advantage comes from fewer trades. Annual rebalancing trades 1 time per year. Threshold rebalancing trades 1.5 times per year. The 0.5 difference is small. The threshold trades only when drift exceeds 5%. The annual trades every year regardless of drift. The threshold saves costs in low-volatility years.
Average rebalancing 1.5 times per year
Average rebalancing is 1.5 times per year for threshold method. Year 1: 0 times. Year 2: 1 time. Year 3: 2 times. Year 4: 1 time. Year 5: 2 times. The average is 1.5 times. The 1.5 times costs $150 annually. The $150 cost is 0.15% of $100,000. The 0.15% cost reduces returns by 0.15%. The 8.3% return is 0.2% higher than 8.1% annual. The threshold method wins.
Tax Implications: Taxable vs IRA vs 401k
Tax implications differ by account type. Taxable accounts pay 15% to 20% capital gains tax on rebalancing trades. IRA and 401k pay 0% tax on rebalancing trades. Tax-loss harvesting offsets $3,000 annually in taxable accounts. Rebalance IRA and 401k first. Rebalance taxable accounts last. This tax strategy saves $10,000+ over 30 years.
Taxable accounts: 15% to 20% capital gains tax
Taxable accounts pay 15% to 20% capital gains tax on rebalancing trades. The 15% rate applies to income under $492,300 for single filers. The 20% rate applies to income over $492,300. The $13,630 stock sale generates $8,000 gain. The 15% tax is $1,200. The $1,200 tax is 8.8% of the sale. The tax reduces rebalancing efficiency. Use taxable accounts for long-term holds.
The $1,200 tax is avoidable in IRA. The IRA rebalancing costs $0 tax. The $1,200 tax difference is significant. Over 30 years, the $1,200 annual tax costs $106,000. The tax savings is massive. Rebalance IRA first. Rebalance taxable last. This strategy preserves wealth.
IRA and 401k: 0% tax on rebalancing trades
IRA and 401k pay 0% tax on rebalancing trades. The trades are tax-free. The gains compound tax-free. The withdrawals are taxed at ordinary income rates. The rebalancing is efficient. Rebalance IRA and 401k annually without tax concerns. The IRA and 401k are optimal for rebalancing. Maximize IRA and 401k contributions.
The 0% tax applies to all trades. Sell winners tax-free. Buy losers tax-free. The portfolio rebalances efficiently. The 0% tax saves $1,200 annually on $100,000. The $1,200 savings compounds to $106,000 in 30 years. The tax savings is significant. Choose IRA and 401k for rebalancing.
Tax-loss harvesting offsets $3,000 annually
Tax-loss harvesting offsets $3,000 annually in taxable accounts. Sell losers to generate capital losses. Use losses to offset capital gains from rebalancing. Remaining losses offset $3,000 ordinary income. Carry forward remaining losses to future years. The $3,000 deduction saves $450 to $900 annually. The tax-loss harvesting reduces rebalancing tax.
The $13,630 stock sale generates $8,000 gain. Sell $10,000 bonds at $2,000 loss. The net gain is $6,000. The 15% tax is $900 instead of $1,200. The $300 tax savings is real. The tax-loss harvesting offsets gains. Use tax-loss harvesting with rebalancing. For tax details, see our capital gains tax explained guide.
| Account type | Rebalancing tax | Capital gains tax | Tax-loss harvesting | Rebalance priority |
|---|---|---|---|---|
| IRA | 0% | 0% | No | 1st |
| 401k | 0% | 0% | No | 1st |
| Taxable | 15% to 20% | 15% to 20% | Yes | Last |
The table compares account types. IRA and 401k pay 0% tax. Taxable pays 15% to 20%. IRA and 401k have no tax-loss harvesting. Taxable has tax-loss harvesting. IRA and 401k are rebalanced first. Taxable is rebalanced last. This priority saves taxes. Follow the priority.
Rebalancing With New Contributions: Zero-Cost Method
Rebalancing with new contributions is a zero-cost method. Direct new money to underweighted assets. Buy bonds and gold instead of stocks. The portfolio rebalances without selling. This saves $100 to $500 annually in transaction costs. The zero-cost method works best for accumulating investors under age 55. Maximize this method for tax efficiency.
Direct new money to underweighted assets
Direct new money to underweighted assets instead of weighted assets. Portfolio is 69/23/8 at $152,972. Target is 60/30/10. Stocks are overweight by 9%. Bonds are underweight by 7%. Gold is underweight by 2%. Direct $10,000 new contributions to $7,000 bonds and $3,000 gold. The portfolio becomes 68/25/9. The drift reduces from 9% to 8%.
Repeat every year. The drift continues to reduce. After 3 years of $10,000 annual contributions, the portfolio becomes 62/27/11. The drift is 2%. The portfolio is near target. The zero-cost method works. The portfolio rebalances without selling. The transaction costs are $0. The tax impact is $0. This method is optimal.
Saves $100 to $500 annually in transaction costs
Saves $100 to $500 annually in transaction costs using zero-cost method. Annual rebalancing costs $100. Quarterly costs $300. Monthly costs $500. Zero-cost method costs $0. The $100 to $500 savings compounds to $10,600 to $53,000 in 30 years. The savings is significant. Use zero-cost method when possible.
The zero-cost method requires new contributions. Investors under age 55 contribute regularly. Investors over age 55 withdraw instead. The zero-cost method works for under age 55. Investors over 55 use annual rebalancing. Match the method to life stage.
Works best for accumulating investors under age 55
Works best for accumulating investors under age 55. These investors contribute $10,000 to $50,000 annually. The contributions rebalance the portfolio. The drift reduces over time. The portfolio stays near target. The zero-cost method is optimal for accumulating investors. Investors over 55 withdraw instead. The zero-cost method does not work.
Combine zero-cost method with threshold method. Use zero-cost for annual contributions. Use threshold for drift exceeding 5%. The combination minimizes costs and taxes. The portfolio stays near target. This is the optimal strategy for most investors. For index fund implementation, see our index funds in the USA article. VTI, BND, GLD rebalance efficiently with zero costs.