A portfolio rebalancing simulator shows how different rebalancing strategies — annual, quarterly, threshold-based, or never — affect your portfolio's long-term growth and risk. Disciplined rebalancing sells high and buys low automatically, but trades off tax efficiency and transaction frequency. See which approach fits your goals.
Portfolio Parameters
Results vary each run due to randomized returns — click multiple times to see range of outcomes
Portfolio Value by Strategy
Actual Stock Allocation Drift — Annual vs Never
Year-by-Year Portfolio Values
| Year | Annual | Semi-Annual | Never |
|---|
How to Use the Portfolio Rebalancing Simulator
Portfolio rebalancing is the process of periodically adjusting your portfolio back to your target asset allocation after market movements have shifted it. A 60/40 stock/bond portfolio might drift to 75/25 after a bull market — rebalancing would sell stocks and buy bonds to restore the original balance.
Step 1: Set Your Target Allocation
Adjust the stocks/bonds/cash sliders to reflect your target allocation. Common allocations are 80/20 (aggressive), 60/40 (moderate), or 40/60 (conservative). The simulator checks that your allocations sum to 100% — if not, it will warn you. A typical 60/40 portfolio with 8% expected stock returns and 4% expected bond returns serves as a useful baseline for comparison.
Step 2: Understand the Six Strategies
The simulator runs six strategies simultaneously with the same randomized return sequence. Annual, semi-annual, and quarterly rebalancing trigger on a calendar schedule. 5% and 10% threshold bands only trigger when stock allocation drifts more than 5% or 10% from target. Never rebalance lets winners run — this maximizes equity exposure in bull markets but can leave you dangerously overweight stocks before a correction.
Step 3: Interpret the Results
Because returns are randomized, click "Run Simulation" several times to see the range of outcomes. Look at two things: (1) final portfolio values — these show which strategy produced the most wealth under this particular return scenario; (2) rebalancing events — threshold strategies typically trigger fewer events than calendar strategies in calm markets but the same number in volatile ones. The drift chart shows how far your actual stock allocation wanders from target in annual vs never strategies — a critical risk visualization.
The Rebalancing Bonus
In volatile markets with mean-reverting returns, systematic rebalancing can add 0.2-0.5% annual return versus never rebalancing at the same overall allocation. This "rebalancing bonus" comes from the forced buy-low/sell-high discipline. However, in trending markets (like the 2010-2021 stock bull run), never rebalancing wins because you allow the outperforming asset to compound uninterrupted. Real markets show both patterns over different periods.
FAQ
Is the portfolio rebalancing simulator free?
Yes, completely free with no signup required. All simulations run locally in your browser using your specified parameters.
How does this simulator differ from a rebalancing calculator?
A rebalancing calculator tells you what to buy and sell today to return to target allocation. This simulator runs forward over 5-40 years, modeling how different rebalancing strategies perform over a full market cycle with randomized annual returns. It shows long-term portfolio value, allocation drift, and the number of rebalancing events for each strategy.
Why does rebalancing actually help portfolio returns?
Rebalancing systematically forces you to sell high (overweighted assets) and buy low (underweighted assets). Over long periods, this 'rebalancing bonus' can add 0.2-0.5% annually to risk-adjusted returns. However, frequent rebalancing triggers tax events in taxable accounts, so the net benefit depends heavily on account type and tax situation.
What is threshold-based rebalancing?
Threshold (or band) rebalancing only triggers when an asset class drifts more than a set percentage from its target. A 5% threshold means you rebalance stocks if they grow from 60% to 65% or above, but not at 62%. This can be more tax-efficient than calendar rebalancing because it only trades when the portfolio is meaningfully out of balance, not on a fixed schedule.
Why does 'never rebalance' sometimes win in simulations?
In bull markets for stocks, never rebalancing allows winners to run — your 60% stock allocation grows to 80%+ over 20 years, which produces higher absolute returns if stocks keep outperforming. The risk is that your actual risk exposure far exceeds your original risk tolerance. A 40-year-old who never rebalances might have a 90% equity portfolio by age 60, which can devastate retirement savings in a crash.
How should I interpret the randomized results?
Each simulation run uses randomly generated returns sampled from a normal distribution with your specified mean and volatility. Results vary between runs. Run the simulation multiple times to see the range of outcomes. The key insight is the relative performance of strategies, not the exact dollar amounts. Annual rebalancing consistently reduces maximum portfolio drawdown vs never rebalancing.
Should I rebalance tax-advantaged vs taxable accounts differently?
Yes. In tax-advantaged accounts (401k, IRA), rebalance as frequently as needed — there are no tax consequences. In taxable accounts, use threshold-based or annual rebalancing to minimize capital gains taxes. Many advisors recommend using new contributions to rebalance in taxable accounts rather than selling overweighted positions.