How to Rebalance a Portfolio and How Often to Do It

You set up a simple mix of stock and bond funds a few years ago, and now your statement shows something you never chose. Stocks had a good run, so a portfolio you built as 70 percent stocks is now 82 percent stocks, and you are carrying more risk than you signed up for. Learning how to rebalance a portfolio fixes that, and it takes less time and math than most people expect.

This guide walks through what rebalancing is, the two main ways to do it, how often makes sense, and how to avoid a surprise tax bill along the way.

What it means to rebalance a portfolio

Your asset allocation is the split between investment types, usually stocks and bonds, that you picked based on your goals and how much a drop would bother you. A 30 year old saving for retirement might choose 80 percent stocks and 20 percent bonds. Someone five years from retirement might choose 50/50.

Markets do not move together, so that split drifts. Rebalancing is simply moving the mix back to your target.

Here is a real example. Say you invested $50,000 at 70 percent stocks ($35,000) and 30 percent bonds ($15,000). Over two years stocks gain 30 percent and bonds gain 4 percent.

The size of the move is the point here. It is about 4.5 percent of the portfolio, not a full overhaul.

Two ways to decide when to rebalance

Calendar rebalancing

You check once a year on a fixed date, say your birthday or the first week of January, and bring everything back to target. It is simple and hard to forget. Research from fund companies such as Vanguard has found that annual rebalancing captures most of the risk control benefit, and that checking monthly or quarterly adds trading without much extra protection.

Threshold rebalancing

You only act when an asset class drifts more than a set amount from its target, commonly 5 percentage points. With a 70/30 target, you would rebalance when stocks pass 75 percent or drop below 65 percent. This responds to big market moves, like a sharp crash, without making you trade in quiet years.

A practical blend: look once a year, but only trade if something is more than 5 points off. That keeps the habit regular and the trading light.

How to rebalance a portfolio step by step

1. Add up every account. Include your 401(k), IRA, and taxable brokerage account. Your allocation is across all of them, not each one separately.
2. Calculate your current split. Total stock fund value divided by total portfolio value gives your stock percentage.
3. Compare to target. If you are within your threshold, stop. You are done for the year.
4. Use new money first. If you contribute every month, direct new contributions toward the underweight asset. On a $500 monthly contribution, sending all of it to bonds for six months moves $3,000 without selling anything.
5. Trade inside tax sheltered accounts next. Selling stock funds and buying bond funds inside a 401(k) or IRA has no tax consequence.
6. Touch the taxable account last. Only sell there if the other steps cannot close the gap.

If you are still choosing what to hold in the first place, our guide to index funds for a first-time investor covers the broad funds that make this process simpler, since fewer funds means fewer numbers to track.

Taxes and costs to watch

In a regular brokerage account, selling a fund that has gained value creates a capital gain. If you have held it more than a year, that is taxed at long-term rates of 0, 15, or 20 percent depending on income. Under a year, it is taxed as ordinary income, which can be much higher. Our explainer on capital gains tax on stocks shows how those brackets apply.

A few ways to keep the bill near zero:

• Do the selling in your 401(k) or IRA instead.
• Rebalance with new contributions and reinvested dividends.
• If you must sell in a taxable account, sell lots you have held more than a year, and pick the lots with the smallest gain.
• Check for trading fees. Most major brokers now charge $0 to trade ETFs and their own mutual funds, but some funds still carry short-term redemption fees if sold within 30 to 90 days.

Where the usual advice falls short

You will often read that you should rebalance quarterly to stay disciplined. For most beginners I think that is too often, and here is why.

Markets tend to trend for months at a time. If you trim stocks every quarter during a long rise, you keep selling your best performer early. Each trade in a taxable account can also trigger a gain. Studies of rebalancing frequency have generally found that annual or threshold methods end with similar risk levels to quarterly ones, with fewer trades and lower costs. More activity mostly creates more moments to second-guess yourself.

The other piece of advice I would question is that rebalancing raises returns. Sometimes it does, especially after a crash when you buy stocks cheaply. But in a long bull market, a portfolio left alone will often finish ahead, because it drifted toward stocks. The real reason to rebalance is to keep your risk where you chose it, not to squeeze out extra return. If you go in with that expectation, you will not feel cheated in the years it lags.

An easier route if you never want to do this

Some people know they will never sit down once a year with a spreadsheet. That is fine. A target date fund or a balanced fund rebalances automatically inside the fund for a single expense ratio, often 0.10 to 0.20 percent at low cost providers. Many robo advisors also rebalance for you for a fee of around 0.25 percent a year. On a $60,000 portfolio that is $150 a year, which is worth comparing against how likely you are to do it yourself. For more on what those percentages mean in real money, see expense ratios explained with real dollar amounts.

Frequently asked questions

How often should I rebalance my portfolio?

Once a year is enough for most long-term investors. Many people pair that with a 5 percentage point threshold, so they only trade when the mix has drifted meaningfully. Checking more often tends to add trades and costs without lowering risk much.

Does rebalancing trigger taxes?

Only when you sell at a gain in a taxable brokerage account. Trades inside a 401(k), IRA, or Roth IRA have no immediate tax effect. You can also rebalance by directing new contributions toward the underweight fund instead of selling.

Is it better to rebalance or let winners run?

Letting winners run can earn more in a long rising market, but it also leaves you with more risk than you planned. Rebalancing keeps your portfolio at the level of risk you chose. For most people, sticking to a plan through a downturn matters more than a slightly higher return.