Portfolio rebalancing means adjusting your investments when their weights move away from your chosen allocation. The purpose is to keep risk aligned with your plan, not to predict which market will rise next. You can rebalance by buying and selling investments, directing new contributions to underweight holdings, or using planned withdrawals to reduce overweight holdings.
A workable process starts with a target, a review schedule and a rule for deciding when drift warrants action. If you have not chosen that target, start with building an investment portfolio through asset allocation. The percentages below are illustrations, not recommendations for your circumstances.
What Portfolio Rebalancing Does—and Does Not Do
Suppose you choose a portfolio of 60% stocks and 40% bonds. After stocks outperform bonds, the mix becomes 70% stocks and 30% bonds. You now have more stock exposure than you intended, even though you have not bought anything.
Rebalancing restores the intended mix. That could mean selling some stock holdings and buying bonds, or adding enough money to bonds to bring the proportions back into line. These are established methods in the SEC’s guidance on asset allocation and rebalancing.
This is risk maintenance, not a promise of better returns. After you trim stocks, they could keep rising. After you buy an underweight asset, it could keep falling. Judge the decision against your allocation rule rather than what prices do the following week.
There is also a difference between restoring a target and changing it. Moving from a drifted 70/30 portfolio back to a planned 60/40 mix is rebalancing. Adopting a new 50/50 target because retirement is approaching is an allocation decision.
When Should You Rebalance a Portfolio?
Choose a rule you can follow without turning portfolio maintenance into a daily occupation. Calendar reviews, allocation thresholds and a combination of both offer different ways to decide when to act.
Calendar Rebalancing
Calendar rebalancing restores target weights at scheduled intervals, such as every six or twelve months. Its attraction is simplicity: the date prompts the decision, rather than a market headline.
Distinguish a scheduled review from a scheduled trade. You could review annually but leave the portfolio alone when it remains within your permitted range. There is little purpose in placing several trades simply to move a holding from 59.8% to exactly 60% unless your policy requires that precision.
Threshold Rebalancing
Threshold rebalancing uses an agreed amount of drift as the trigger. With a 60% stock target and a five percentage point tolerance, the stock allocation has a permitted range of 55% to 65%. Your policy should state whether reaching the boundary or moving beyond it triggers action.
Percentage points and percentage changes are different. A move from 60% to 65% is five percentage points, but an increase of about 8.3% relative to the target weight. Both absolute and relative thresholds appear in the CFA Institute’s discussion of rebalancing rules.
That distinction matters for smaller holdings. A five percentage point allowance around a 5% target permits a range from zero to 10%. A relative tolerance of 20% produces a much narrower range of 4% to 6%. Neither is automatically correct; choose a band that reflects the role and acceptable size of that holding.
Combining Reviews and Thresholds
A practical policy could check allocations quarterly, trade only when a boundary is breached, and reassess the investment plan annually. This separates checking from trading while providing regular opportunities to catch drift.
Review the target outside that schedule if your circumstances change: an earlier retirement, a new spending requirement or a reduced ability to absorb losses. First decide whether the old allocation still fits. Restoring an unsuitable target with great precision does not make it suitable.
How to Calculate a Portfolio Rebalance
Use current market values, not the amounts originally invested. Define which accounts belong to the goal you are managing, then classify their holdings consistently. For this exercise, keep an emergency reserve or a separate house deposit outside the retirement portfolio calculation.
The basic calculations are:
Current weight = asset class value ÷ total portfolio value × 100
Target dollar value = total portfolio value × target allocation
Assume a portfolio is now worth $120,000, comprising $84,000 in stock funds and $36,000 in bond funds. Its target remains 60% stocks and 40% bonds.
| Asset class | Current value | Current weight | Target value | Adjustment |
|---|---|---|---|---|
| Stocks | $84,000 | 70% | $72,000 | Sell $12,000 |
| Bonds | $36,000 | 30% | $48,000 | Buy $12,000 |
| Total | $120,000 | 100% | $120,000 | No change before costs |
Selling $12,000 of stock funds and buying $12,000 of bond funds restores the target before taxes, transaction costs and subsequent price changes. The calculation uses the current $120,000 balance, not the portfolio’s starting value.
For several asset classes, repeat the calculation for each. Without external cash flows or costs, the required purchases should equal the required sales. If they do not, check for omitted cash, double counting or percentages that do not total 100%.
Also check what sits inside each category. A portfolio can meet its stock and bond targets while holding too much of one company or sector. Keep that separate check focused on diversification and concentration risk; restoring broad percentages does not resolve every exposure within them.
Use Contributions and Withdrawals Before Selling
Before placing sales, calculate what incoming money can accomplish. Directing new contributions to underweight asset classes can bring a portfolio closer to its target without selling existing investments. Redirecting contributions is one of the approaches covered by FINRA’s portfolio rebalancing guidance.
Using the same example, suppose you add $10,000 and invest it entirely in bonds. Stocks remain worth $84,000, bonds rise to $46,000, and the portfolio totals $130,000. The stock weight falls from 70% to approximately 64.6%.
That brings the portfolio inside an illustrative 55% to 65% stock range, but it does not restore the exact 60% target. To do that using new money alone, with prices unchanged, you would need to add $20,000 to bonds: $84,000 divided by the resulting $140,000 total equals 60%.
Contributions therefore need to be large enough relative to the portfolio to correct the drift within an acceptable period. If they are not, decide whether a partial sale is warranted rather than leaving an unwanted allocation in place indefinitely.
Withdrawals can serve the same purpose in reverse. If the example portfolio needs a $10,000 withdrawal, taking it entirely from stocks leaves $74,000 in stocks and $36,000 in bonds. Stocks would still represent about 67.3% of the remaining $110,000. Recalculate after the withdrawal; withdrawing from an overweight holding does not necessarily finish the rebalance.
Check Taxes Before Choosing What to Sell
The following tax discussion concerns US federal rules; state and non-US treatment can differ.
In a taxable account, selling an appreciated investment generally realizes a capital gain even if you immediately reinvest the proceeds. Review the cost basis and holding period of the shares you intend to sell. Gains on investments held for more than one year are generally long term; those held for one year or less are generally short term.
If selling at a loss, check purchases as well as sales. The wash sale rules can disallow a loss deduction when you acquire substantially identical securities within 30 days before or after the sale. Relevant purchases can include dividend reinvestments and acquisitions in another account, including an IRA. These rules are detailed in IRS Publication 550 on investment income, capital gains and wash sales.
Do not assume the platform’s default share selection produces the tax outcome you intended. Check the proposed shares, estimated gain or loss, and any identification requirements before submitting the order.
For a material tax bill, ask a qualified tax professional to compare the available routes. The useful question is not simply how to avoid tax, but how much tax and trading cost each route creates while correcting the unwanted exposure.
Coordinate Accounts Without Moving Money Between Them
If several accounts support the same goal, assess their combined allocation before deciding where to trade. They do not each need identical stock and bond percentages.
Rebalancing within a traditional IRA can avoid realizing a current taxable capital gain from an ordinary investment sale inside that account. Amounts in a traditional IRA, including earnings and gains, are generally not taxed until distribution under the IRS rules for traditional IRAs. Trading within the account and withdrawing money from it are different actions.
Suppose your taxable account is overweight stocks, but your IRA holds enough stocks to make the required adjustment there. Selling stocks and buying bonds inside the IRA could restore the combined target without selling the taxable holdings. No money needs to move between accounts.
Treat this as a starting calculation, not a complete tax plan. A dollar in a traditional IRA does not necessarily provide the same after-tax spending power as a dollar in a Roth IRA. Record the account boundaries used in your allocation policy so that each review remains comparable.
Check Fund Mechanics and Automatic Rebalancing
Before submitting orders, review transaction charges, redemption restrictions and the cash needed for purchases. When estimating the adjustment, allow for costs rather than assuming every dollar sold becomes a dollar invested. For portfolios built with funds, the guide to index funds and ETFs covers the investment structures separately.
After execution, verify the resulting balances and weights. Use actual trades, not the order preview. If you redirected contributions temporarily, set a reminder to reassess them; otherwise, a correction can become a new source of drift.
A target date fund may already handle the rebalancing within its portfolio and change its allocation along a planned path as the target date approaches. Funds with the same target year can still have different allocations, risks and fees, as detailed in the SEC investor bulletin on target date funds.
If you hold one alongside separate stock and bond funds, include its underlying exposures in the combined calculation. Buying an extra stock fund changes your total mix even though the target date fund continues following its own policy.
Write a Rebalancing Rule You Can Follow
A short written policy removes much of the guesswork. Record:
- The accounts included and target weights for each asset class.
- The review dates and allocation boundaries that trigger action.
- Whether a trade restores the target or stops at a chosen point inside the range.
- How contributions, withdrawals, taxes and costs affect the order of adjustments.
An illustrative rule might be: “Review quarterly. Rebalance if stocks move outside 55% to 65% of the portfolio. Use available contributions first, then assess sales needed to restore the 60% target. Review the target annually or after a material change in circumstances.”
Keep a brief record of each decision, including deliberate decisions not to trade. The test is whether the portfolio remains aligned with its purpose at an acceptable cost—not whether every review produces an order.