What is rebalancing?
Rebalancing is the process of buying and selling assets to return your portfolio to its target allocation. Over time, winners grow and losers shrink, so a 60/40 stock/bond portfolio might drift to 75/25 — making it riskier than you ever intended.
Rebalancing sells some of what grew and buys what lagged, restoring your intended risk level. It is a discipline, not a prediction. You are not guessing where the market goes next — you are simply bringing the portfolio back to the mix you chose when you were thinking clearly.
Why portfolios drift
Imagine you start at 60% stocks / 40% bonds. After a strong bull run, stocks climb so much that they become 75% of the portfolio. You now have far more risk than you signed up for — and you are most exposed right before a potential downturn.
That is the quiet danger of drift: it increases your risk exactly when markets are euphoric, the precise moment you can least afford a sharp pullback. Nobody decided to take on more risk; the market decided it for you while you were not looking.
In short
A 60/40 portfolio that drifts to 75/25 is no longer a 60/40 portfolio. Without rebalancing, your allocation is set by recent performance — not by your plan.
Two rebalancing methods
There are two main ways to decide when to rebalance. Each has clear trade-offs:
| Method | Trigger | Pros | Cons |
|---|---|---|---|
| Calendar | A fixed schedule (annually or semi-annually) regardless of drift | Simple, predictable, low effort | May trade when little has changed, or miss large mid-period drift |
| Threshold | Only when an asset drifts beyond a set band (e.g. ±5% from target) | More responsive, fewer unnecessary trades | Requires ongoing monitoring of your allocation |
Many investors combine the two: check annually, act only if drift exceeds 5%. You get the simplicity of a schedule with the responsiveness of a threshold, and you avoid trading for the sake of trading.
How often should you rebalance?
Research consistently shows that rebalancing once a year captures most of the benefit. More frequent rebalancing — quarterly or monthly — adds transaction costs and taxes without meaningfully improving results.
For most investors, annual or threshold-based (±5%) rebalancing is the sweet spot. It is frequent enough to control risk, but infrequent enough to keep costs and tax drag low. There is no prize for rebalancing constantly — only more friction.
Tax-smart rebalancing
In taxable accounts, selling appreciated holdings can trigger capital gains taxes. A few habits let you rebalance while keeping the tax bill low:
Rebalance inside tax-advantaged accounts first
Selling within IRAs and 401ks has no immediate tax consequences, so do as much of your rebalancing there as possible.
Use new contributions to rebalance
Direct fresh money to the underweight asset instead of selling the overweight one. This nudges your allocation back toward target without realizing any gains.
Direct dividends to the lagging asset
Instead of reinvesting dividends back into whatever produced them, point them at the asset class that has fallen behind your target.
Mind capital gains in taxable accounts
When you must sell appreciated holdings in a taxable account, favor positions held over a year so you pay lower long-term gains rates rather than higher short-term rates.
Pair with tax-loss harvesting
In down markets, tax-loss harvesting can pair naturally with rebalancing — you sell losers to capture deductible losses while bringing your allocation back in line.
Common rebalancing mistakes
Rebalancing is simple in theory, but a handful of mistakes quietly undermine it:
Rebalancing too often
Constant trading lets transaction costs and taxes eat into your returns without improving outcomes.
Never rebalancing
Letting the portfolio run means risk silently balloons until a downturn reveals how exposed you really were.
Rebalancing emotionally
Selling everything in a panic is not rebalancing — it is the exact behavior rebalancing is meant to protect you from.
Ignoring the tax impact
Selling appreciated holdings in a taxable account without a plan can hand a meaningful chunk of your gains to taxes.
Forgetting to view accounts as one portfolio
Rebalance across account types as one combined portfolio. Treating each account in isolation leads to a messier, less tax-efficient overall allocation.
Build and maintain your allocation
Compare funds for each asset class, then use new contributions to nudge your portfolio back to target without selling.
The bottom line
Rebalancing is the unglamorous discipline that quietly protects you from yourself. It forces you to sell what is expensive and buy what is cheap, keeps your risk level where you intended it, and removes emotion from the equation. You don't need to do it often — once a year, or whenever an asset drifts more than 5% from target, is plenty. Set a date, check your allocation, make the trades, and get on with your life. The goal isn't to maximize returns; it's to stay on the path you chose when you were thinking clearly.
Frequently asked questions
How often should I rebalance my portfolio?+
For most investors, once a year is enough to capture the majority of the benefit. Alternatively, you can use a threshold approach — rebalancing only when an asset class drifts more than about 5% from its target. Rebalancing more frequently tends to add transaction costs and taxes without improving results.
What is the difference between calendar and threshold rebalancing?+
Calendar rebalancing happens on a fixed schedule, such as every January, regardless of how much your portfolio has drifted. Threshold rebalancing happens only when an asset class moves beyond a set band, like 5% from its target. Many investors combine both: check on a schedule, but only trade if drift is significant.
Does rebalancing improve my returns?+
Rebalancing is primarily a risk-control tool, not a return-maximizing one. It keeps your portfolio risk level consistent with your plan. As a side benefit, it imposes a buy-low, sell-high discipline by trimming what has risen and adding to what has lagged, but the main purpose is keeping your risk where you intended.
How do I rebalance without paying a lot of taxes?+
Rebalance inside tax-advantaged accounts like IRAs and 401ks first, where selling has no immediate tax cost. In taxable accounts, direct new contributions and dividends toward the underweight asset to rebalance without selling. When you must sell appreciated holdings in a taxable account, favor positions held over a year for lower long-term capital gains rates.
What happens if I never rebalance?+
Without rebalancing, your highest-performing assets keep growing as a share of your portfolio, steadily increasing your risk. A portfolio that started at 60% stocks could drift to 80% or more after a long bull market, leaving you far more exposed to a downturn than you intended — often right before one arrives.