How to Rebalance Your Portfolio (And When to Do It)

Rebalancing is the process of realigning your portfolio back to its target allocation — and in our experience, it's the single most neglected habit among individual investors. It means — selling positions that have grown beyond their intended weight and adding to those that have shrunk. It's portfolio maintenance: ensuring that market movements haven't drifted your actual allocation far from your intended allocation. Done properly, it controls risk and enforces the discipline of buying low and selling high.

Why Portfolios Drift

If you start with a portfolio of 20 stocks at 5% each, it won't stay that way. Some stocks will outperform and grow to 7-8% of the portfolio. Others will underperform and shrink to 2-3%. After a year, your portfolio might have three positions above 7% and five below 3% — even though you made no changes. The drift is automatic, driven entirely by differential performance.

At the asset-class level, the same drift occurs between stocks and bonds. A 70/30 stock-bond portfolio might drift to 80/20 after a strong stock market year — meaning your portfolio is now meaningfully more aggressive than you intended. The additional 10% stock exposure increases your downside risk during the next bear market beyond what your risk tolerance can handle.

When to Rebalance

Threshold-Based (Recommended)

Rebalance when any position drifts more than 2-3 percentage points from its target weight, or when your stock-bond allocation drifts more than 5 percentage points. A stock that's grown from 5% to 8% has drifted 3 points — time to trim. A stock that's shrunk from 5% to 2% has drifted 3 points — time to add (if the thesis is intact).

Threshold-based rebalancing is more efficient than calendar-based because it triggers action only when drift is meaningful. If the portfolio hasn't drifted significantly, no rebalancing is needed — saving you transaction costs and tax consequences.

Calendar-Based

Alternatively, review your portfolio quarterly or semi-annually and rebalance any positions that have drifted significantly. This is simpler and requires less monitoring than threshold-based rebalancing. The slight inefficiency (you might rebalance when drift is minimal) is offset by the simplicity and consistency of a fixed schedule.

How to Rebalance Tax-Efficiently

Selling winners triggers capital gains taxes. To minimize the tax impact, prioritize rebalancing through new contributions rather than selling: direct new investment dollars toward the underweight positions rather than selling overweight ones. This achieves the same rebalancing effect without triggering taxable events.

In tax-advantaged accounts (401k, IRA, Roth IRA), rebalance freely — there are no tax consequences to buying and selling within these accounts. Save your most active rebalancing for these accounts and let taxable accounts drift slightly wider before triggering taxable sales.

When you must sell in taxable accounts, harvest losses elsewhere in the portfolio to offset the gains. And always hold rebalanced positions for at least a year to qualify for long-term capital gains rates rather than short-term rates.

When Not to Rebalance

Don't automatically trim every winner. If a stock has grown from 5% to 8% of your portfolio because the business is performing exceptionally — growing revenue, expanding margins, widening its moat — the price appreciation reflects genuine value creation. Trimming it mechanically means selling your best-performing, highest-quality holding simply because it did what you bought it to do.

Quality investors should rebalance more thoughtfully than mechanical rules suggest. Trim when the valuation has become stretched (P/FV significantly above 1.0), not simply when the position size has grown. A position growing because the business is compounding at 20% annually might deserve to remain your largest holding — the business quality justifies the concentration.

The balance is between risk management (no single position so large that a company-specific event devastates your portfolio) and letting winners run (not selling your best businesses just to enforce arbitrary allocation targets). For most investors, a maximum position of 8-10% strikes this balance well.