Key Takeaways
- Markets naturally cause your portfolio's asset mix to drift from its original target over time.
- Rebalancing restores your intended balance between assets like stocks, bonds, and cash.
- Investors use time-based or threshold-based rules to decide when to rebalance.
- Rebalancing in tax-advantaged accounts avoids immediate tax consequences from selling.
- Rebalancing is about managing risk, not chasing higher returns.
Portfolio Rebalancing
Rebalancing is the process of adjusting the mix of investments in a portfolio to bring it back to a planned target. Over time, some investments grow faster than others, which shifts the original balance. Rebalancing corrects that drift by selling some of what has grown and buying more of what has shrunk.
Rebalancing can trigger taxable events in non-tax-advantaged accounts, so investors often consider the tax implications before selling appreciated assets.
Why Portfolios Drift Over Time
When you first invest, you typically choose a mix of assets — perhaps stocks for growth and bonds for stability. That mix reflects your goals and how much risk you are comfortable taking. To understand what each asset class does, see our guide to stocks, bonds, and cash.
The problem is that different assets grow at different rates. Stocks, for example, tend to outperform bonds during strong market periods. If your stocks rise sharply over a year, they will make up a larger share of your portfolio than you originally intended. This is called drift — and it happens automatically, without you doing anything wrong.
Drift matters because it changes your risk exposure. A portfolio that started as 60% stocks and 40% bonds might become 75% stocks and 25% bonds after a sustained rally. That extra stock weight means your portfolio is now more sensitive to market swings than you planned for. Market volatility can then affect you more severely than your original plan anticipated.
5–10%
Common drift threshold that triggers rebalancing
Many financial planning frameworks suggest rebalancing when any asset class moves more than 5 to 10 percentage points from its target weight.
1x/year
Typical rebalancing frequency for many investors
Annual rebalancing is widely cited in personal finance literature as a common and manageable interval for most long-term investors.
60/40
Classic stock-to-bond portfolio target allocation
The 60% stocks, 40% bonds allocation has been a longstanding reference point in portfolio construction discussions, though individual targets vary widely.
What Rebalancing Actually Involves
Rebalancing is a straightforward corrective action: you sell some of the assets that have grown beyond their target percentage and use the proceeds to buy more of the assets that have fallen below their target. The goal is to return to your original intended allocation.
For example, if your target is 60% stocks and drift has pushed that to 72%, you might sell enough stocks to bring them back to 60% and use the money to top up your bond holdings. This is sometimes described as "trimming your winners and adding to your laggards."
Another approach is to direct new contributions toward underweighted assets rather than selling anything. If you are regularly adding money to your portfolio — through paycheck contributions to a 401(k), for instance — you can steer that new money toward whatever is below its target. This avoids triggering any sales and the costs that come with them.
Use New Contributions to Rebalance First
Before selling existing holdings to rebalance, check whether directing new money into underweighted assets can do the job. This approach avoids generating taxable gains and keeps transaction costs low. It works especially well for investors who contribute regularly to retirement accounts.
Two Common Approaches to Timing
Investors generally use one of two frameworks to decide when to rebalance:
- Calendar-based rebalancing: You review and adjust your portfolio on a fixed schedule — quarterly, semi-annually, or annually. This is simple and disciplined, requiring no constant monitoring.
- Threshold-based rebalancing: You only rebalance when an asset class drifts beyond a defined boundary — commonly 5 percentage points from its target. This approach is more responsive to market conditions but requires you to monitor your portfolio more actively.
Some investors combine both: they check their portfolio on a regular schedule and only act if drift exceeds a set threshold. This balances simplicity with responsiveness.
For those approaching or already in retirement, rebalancing decisions are closely tied to how assets are being drawn down. Our article on how budgeting changes when you retire explains how the shift from accumulation to withdrawal affects financial priorities.
Rebalancing, Taxes, and Automatic Options
Where you rebalance matters as much as when. Inside tax-advantaged accounts like a 401(k) or IRA, you can sell and buy without triggering an immediate tax bill. In a taxable brokerage account, selling appreciated investments generates capital gains, which may be taxable in the year of the sale.
For investors who prefer a hands-off approach, target-date funds handle rebalancing automatically, adjusting the asset mix over time without requiring any action from the investor. This can be a practical option for those who want a structured, self-managing approach.
Understanding rebalancing is part of the broader practice of asset allocation — deciding how your money should be divided across investment types in the first place. Rebalancing is how you preserve that decision over time.
This article is for general informational and educational purposes only and does not constitute personalized financial, investment, tax, or legal advice. Consult a qualified financial adviser or tax professional before making decisions based on your individual circumstances.