You built a portfolio with a specific allocation — say, 80% stocks and 20% bonds. A year later, a strong stock market has pushed your portfolio to 88% stocks and 12% bonds. Your actual risk level is now higher than you intended. Rebalancing fixes this.
It sounds simple. The execution has real tax and behavioral implications that most guides skip over.
What rebalancing actually does
When one asset class outperforms, it grows to represent a larger share of your portfolio than your target. Rebalancing brings it back by selling the winners and buying the laggards.
This is counterintuitive — you’re selling what went up and buying what went down. That’s the point. You’re enforcing a buy-low, sell-high discipline automatically, without trying to time the market.
Rebalancing does not improve returns on average. Studies are mixed — some show a small return benefit, some show none. What it does reliably is control risk. If you don’t rebalance a portfolio that started at 60/40 stocks/bonds, after 20 years of equity outperformance you might have a 90/10 portfolio — far more volatile than you signed up for.
How often should you rebalance?
Three approaches work:
Calendar rebalancing: Rebalance on a fixed schedule — once a year, or twice a year. Simple and predictable. Annual rebalancing is the most common recommendation because it minimizes transaction costs and tax events while still keeping allocation reasonably on target.
Threshold rebalancing: Rebalance when any asset class drifts more than X% from target. Common thresholds are 5% absolute (stocks are 80% when target is 75%) or 25% relative (bonds drop from 20% target to below 15%). This is more precise than calendar rebalancing but requires monitoring.
Hybrid: Rebalance annually, but also check whenever markets have a large move. If stocks drop 20% in a month, that’s a natural rebalancing opportunity.
For most individual investors, annual rebalancing is the right answer. The theoretical benefits of more frequent rebalancing don’t justify the additional transaction costs and complexity.
The tax problem with rebalancing in taxable accounts
In a 401(k) or IRA, rebalancing is free — you pay no taxes when you sell within a tax-advantaged account. Do it as often as you want.
In a taxable brokerage account, selling appreciated assets triggers capital gains taxes. If you sell $10,000 of stock that you paid $6,000 for, you owe tax on $4,000 in gains. At 15% long-term capital gains rate, that’s $600 in tax — paid to rebalance, not to earn money.
Strategies to minimize rebalancing taxes:
Direct new contributions to underweight assets. If stocks are overweight and you’re adding new money, put it all into bonds until you’re back in balance. No selling, no tax event.
Rebalance in tax-advantaged accounts first. Sell overweight assets in your 401(k) or IRA, where there’s no immediate tax consequence. Leave your taxable account untouched or use it only for new contributions.
Use dividends and distributions. Automatically reinvest dividends into underweight asset classes instead of pro-rata.
Wait for long-term status. If an asset is overweight and you’re approaching the 1-year mark on gains, waiting to cross into long-term capital gains territory (taxed at 0%, 15%, or 20% depending on income) versus short-term (taxed as ordinary income) can save meaningfully.
Step-by-step: how to actually rebalance
Step 1: Find your current allocation.
Log into all accounts. Add up the total value in each asset class across all accounts (stocks, bonds, international, real estate, etc.). Calculate percentages.
Step 2: Compare to your target.
Write down where you are vs. where you want to be. A simple spreadsheet or a tool like Personal Capital/Empower does this automatically.
Step 3: Determine what to sell and buy.
Calculate how much of each asset class to sell/buy to return to target. Example: you have $100,000 with stocks at 88% ($88,000) and target is 80% ($80,000). You need to move $8,000 from stocks to bonds.
Step 4: Execute in the right account order.
Start with tax-advantaged accounts. Only sell in taxable accounts if necessary, and only after considering the tax cost.
Step 5: Document and set next review date.
Note the date, what you did, and when you’ll review again.
Rebalancing a three-fund portfolio
If you hold a three-fund portfolio (US stocks, international stocks, bonds), rebalancing means checking the ratio between these three funds once a year and adjusting.
The math is simple because there are only three things to track. Most target-date funds rebalance automatically — one reason they’re popular for 401(k)s.
When not to rebalance
When the tax cost exceeds the benefit. If selling overweight assets triggers large short-term capital gains, the tax cost may outweigh the risk-reduction benefit of rebalancing. Run the numbers.
When you’re close to retirement and shifting allocation anyway. If you’re reducing equity exposure over time, you may simply be letting the natural drift do the work before executing a planned reduction.
When the drift is minor. A 2% drift from target in a $50,000 portfolio is $1,000 — not worth incurring transaction costs or tax events. Set a meaningful threshold.
FAQ
Does rebalancing hurt returns?
Not significantly. Research shows rebalancing has a small positive, negative, or neutral effect on returns depending on the time period studied. Its purpose is risk control, not return enhancement.
Should I rebalance my 401(k) separately from my IRA and taxable account?
Treat all accounts as one portfolio. Optimize the location of assets (bonds in tax-advantaged accounts, equities in taxable) but balance the overall allocation across all accounts together.
What if I use target-date funds?
Target-date funds rebalance automatically. If 100% of your portfolio is in target-date funds matching your retirement year, you don’t need to do anything.
Is there a rebalancing tool I can use?
Vanguard, Fidelity, and Schwab all have portfolio analysis tools that show your current allocation. Personal Capital (now Empower) and Morningstar’s portfolio tracker work across accounts. A simple spreadsheet also works.