What Is Portfolio Rebalancing?
Portfolio rebalancing is the process of realigning your investment mix back to your target allocation. Markets move every day, so a portfolio that started at 60% stocks and 40% bonds might drift to 70/30 after a bull run. Rebalancing forces you to sell high and buy low — the opposite of what most investors do emotionally.
Without rebalancing, your portfolio takes on more risk than you intended. A portfolio that drifts from 60/40 to 80/20 has nearly doubled its equity risk. Rebalancing is the single most reliable way to maintain your risk profile over time.
Popular Portfolio Allocations
| Strategy | Stocks | Bonds | Other | Best For |
|---|---|---|---|---|
| 60/40 Classic | 60% | 40% | — | Balanced investors, nearing retirement |
| 80/20 Growth | 80% | 20% | — | Long-horizon investors, 20+ years to retirement |
| Three-Fund Portfolio | 50% US, 20% Intl | 30% | — | Bogleheads, low-cost index investors |
| Target Date 2050 | 85–90% | 10–15% | — | Set-and-forget investors, auto-adjusts over time |
| All-Weather | 30% | 55% | 15% (Gold, Commodities) | Risk-averse investors, any market condition |
When Should You Rebalance?
There are two schools of thought: calendar-based (quarterly, semi-annually, or annually) and threshold-based (whenever any asset drifts more than 5% from its target). Research from Vanguard shows both approaches produce similar long-term results. Pick one and stick with it.
Annual rebalancing is the sweet spot for most people. It's frequent enough to manage risk but infrequent enough to keep trading costs and tax events minimal. If you're in a tax-advantaged account (401k, IRA), rebalance more frequently since there are no tax consequences.
Tax Implications of Rebalancing
In taxable brokerage accounts, selling winners to rebalance triggers capital gains tax. Short-term gains (held less than a year) are taxed at your ordinary income rate — up to 37%. Long-term gains get preferential rates of 0%, 15%, or 20% depending on your income bracket.
Tax-loss harvesting can offset some of these gains. If you have positions trading below your cost basis, selling those losses can reduce your tax bill. Just watch for the wash sale rule: you can't repurchase a substantially identical security within 30 days.
Rebalancing With New Money vs Selling
The most tax-efficient way to rebalance is to direct new contributions toward underweight assets instead of selling overweight ones. If your stocks are above target, put your next 401k contribution entirely into bonds until the allocation corrects itself. No selling, no taxes, no transaction costs.
This works well when your contributions are large relative to your portfolio (typically early in your investing career). As your portfolio grows, contributions become a smaller percentage, and you may eventually need to sell to rebalance. At that point, prioritize selling within tax-advantaged accounts first.
For splitting your budget across categories, try our percentage split calculator. To plan how much to save each month toward a target, use the savings goal calculator.