Why You Should Rebalance Your Investment Portfolio Regularly

What rebalancing means and why it matters

Rebalancing means selling some of your investments that have grown and buying more of the ones that have fallen behind, so your portfolio returns to the mix you originally chose. Over time, your winners grow larger and your losers shrink, shifting your portfolio away from your plan. Rebalancing brings it back into line.

This matters because your original mix — say, 60% stocks and 40% bonds — was built around your age, how much risk you can handle, and when you need the money. When stocks surge and bonds lag, you end up with 70% stocks and 30% bonds without meaning to. That's riskier than you signed up for. Rebalancing locks in gains from your winners and buys low in your losers, which is the opposite of what most people do naturally.

You don't rebalance to beat the market or time it perfectly. You rebalance to stay on the plan you made when you were thinking clearly, not when emotions are running high.

Key Takeaways

• Rebalancing means selling investments that have grown and buying ones that have fallen behind to return to your original target mix.
• Without rebalancing, your portfolio drifts toward whatever performed best recently, which may be riskier than you intended.
• Rebalancing forces you to sell high and buy low, which is the opposite of what most investors do by instinct.
• How often you rebalance depends on your situation, but once or twice a year works for most people with long time horizons.
• Rebalancing costs money in taxes and trading fees, so doing it too often can erase the benefit.

How your portfolio drifts without rebalancing

Imagine you start with $100,000 split evenly: $50,000 in stocks and $50,000 in bonds. Stocks rise 20% in a year, bonds rise 2%. Now you have $60,000 in stocks and $51,000 in bonds — your 50/50 split is now 54/46. That doesn't sound like much, but it compounds. After five years of similar returns, you might be at 65/35 without touching anything.

The problem is that you didn't choose 65/35. You chose 50/50 because that mix matched your comfort with risk and your timeline. A 65/35 portfolio is more aggressive — it can swing wider in bad years. If a market crash happens when you're at 65/35 instead of 50/50, your losses are bigger than you planned for. You may panic and sell at the worst time, locking in losses.

Rebalancing prevents this drift. It keeps your portfolio aligned with the plan you made, not the plan the market made for you.

When to rebalance and how often

There's no single right answer, but most people with a long time horizon rebalance once or twice a year. Some rebalance when any part of their portfolio drifts more than 5% from its target — so if stocks were supposed to be 60% and they've grown to 65%, that's the signal to rebalance. Others pick a calendar date, like January 1st or their birthday, and rebalance then no matter what.

The calendar approach is simpler and works well if you're not checking your portfolio constantly. The drift-based approach is more precise but requires you to monitor your balances. If you rebalance too often — every month, say — you'll pay trading fees and taxes that eat into your returns. If you rebalance too rarely — every five years — your portfolio may drift so far that it no longer matches your risk tolerance.

People who are retired or close to it may rebalance more often because they're taking money out and need to be more careful about staying on track. People with decades until retirement can rebalance less often because time smooths out the bumps.

The tax and fee cost of rebalancing

Every time you sell an investment in a taxable account, you may owe capital gains tax on the profit. If you rebalance too often, those taxes add up and reduce your returns. In a retirement account like a 401(k) or IRA, you don't pay tax on the sale itself, so rebalancing is cheaper there.

Trading fees are smaller than they used to be — many brokers charge nothing to buy or sell stocks and funds — but they still exist for some investments. If you're rebalancing a small portfolio, the fees matter more. If you're rebalancing a large one, they're usually negligible.

The key is balance: rebalance often enough to keep your portfolio on track, but not so often that taxes and fees eat the benefit. For most people, once or twice a year is the sweet spot. If you're in a taxable account and you have large gains, you might rebalance less often or do it gradually over several months to spread out the tax hit.

How to rebalance in different account types

In a 401(k) or traditional IRA, rebalancing is straightforward. You log in, see your current balances, and move money between your investment options — usually mutual funds or target-date funds. There's no tax consequence inside the account, so you can rebalance as often as you want without worrying about capital gains tax.

In a taxable brokerage account, you have more to think about. Selling a fund or stock that's gone up triggers a capital gains tax bill. You can reduce the tax hit by selling investments that have losses (a strategy called tax-loss harvesting), or by rebalancing gradually — selling a little each month instead of all at once. Some people rebalance by directing new contributions toward the underweight parts of their portfolio instead of selling winners.

If you have accounts at multiple brokers, you can rebalance across all of them together. Look at your total holdings everywhere, figure out what your target mix should be, and then adjust each account to move toward that goal. This is especially useful if one account is tax-advantaged and another is taxable — you can do the rebalancing in the tax-advantaged account and leave the taxable one alone.

Common mistakes people make when rebalancing

The biggest mistake is not rebalancing at all. People set up a portfolio and then ignore it for years, letting it drift further and further from the original plan. By the time they check, they're holding far more risk than they intended.

The second mistake is rebalancing too often, usually because someone read an article about market timing or got nervous about recent news. Rebalancing every month or every time the market moves 5% costs more in fees and taxes than it saves.

A third mistake is rebalancing without thinking about taxes. Selling a fund with a huge gain in a taxable account can create a tax bill that wipes out the benefit of rebalancing. Before you rebalance, think about whether you're in a tax-advantaged account or a taxable one, and whether the investment you're selling has a big gain.

Finally, some people rebalance and then when ready second-guess themselves. They sell stocks because they've grown too large, then watch stocks rise further and feel they made a mistake. Rebalancing is about sticking to your plan, not about predicting what will happen next. If you rebalance and then panic, you've defeated the whole purpose.

Rebalancing with new money and withdrawals

If you're adding money regularly — through paychecks into a 401(k), for example — you can use that new money to rebalance. Instead of buying more of your largest holding, direct the new money toward the parts of your portfolio that have fallen behind. This rebalances without selling anything and without triggering taxes.

If you're taking money out — because you're retired or need cash — you can rebalance by withdrawing from your largest holdings. This brings your portfolio back into balance while also giving you the cash you need. Again, no selling of winners, no capital gains tax.

This approach works best if your new contributions or withdrawals are large enough to make a real difference. If you're adding $200 a month to a $500,000 portfolio, directing that money strategically helps but won't fully rebalance you. You'll still need to rebalance the rest of the portfolio periodically.

Frequently Asked Questions

Should I rebalance if my portfolio is still within my target range?

No. If you set a 5% drift threshold and your stocks are at 62% when they should be 60%, you don't need to do anything yet. Rebalancing costs money, so only do it when the drift is large enough to matter. Most people pick a threshold of 5% and rebalance when any part of their portfolio crosses it.

Can I rebalance by just buying more of the underweight parts instead of selling winners?

Yes, and this is a smart move in a taxable account. If you have new money to invest, direct it toward the parts of your portfolio that have fallen behind. This rebalances without triggering capital gains tax. You'll eventually need to sell winners if the drift gets large, but this approach delays it and reduces the tax hit.

What if I have a 401(k) and a taxable brokerage account?

Treat them as one portfolio when you rebalance. Look at your total holdings across both accounts, figure out your target mix, and then adjust each account toward that goal. Do the rebalancing in the 401(k) first since there's no tax cost, and then adjust the taxable account only if you still need to. This minimizes your tax bill.

Is rebalancing the same as dollar-cost averaging?

No. Dollar-cost averaging means investing the same amount at regular intervals, regardless of market price. Rebalancing means adjusting your portfolio back to your target mix. They're different strategies, though you can combine them — for example, by dollar-cost averaging new contributions into the underweight parts of your portfolio.

Do I need to rebalance if I own a target-date fund?

No. Target-date funds rebalance themselves automatically as you get closer to retirement. The fund manager shifts the mix from stocks toward bonds over time, so you don't have to do anything. If you own only a target-date fund, you don't need to rebalance it yourself.