Rebalancing is the simple discipline of returning your portfolio to its target allocation, selling what’s grown and buying what’s lagged. It’s how you keep risk in check without predicting markets.
What “drift” means
Say you target 80% stocks and 20% bonds. After a bull market, stocks might grow to 90% of your portfolio. That “drift” means you’re taking more risk than you planned, without choosing to. Rebalancing sells some stocks and buys bonds to restore the 80/20 split.
Why it matters
Drift quietly increases your risk. Investors who never rebalance end up with stock-heavy portfolios right before crashes, the worst possible timing. Rebalancing forces you to sell high and buy low, systematically, without emotion.
A worked example: rebalancing $100,000
Start with $100,000 at 80/20: $80,000 in stocks, $20,000 in bonds. After a strong bull market, stocks grow to $90,000 while bonds sit at $10,000, so you’re now at 90/10. To rebalance, sell $10,000 of stocks and buy $10,000 of bonds, restoring $80,000/$20,000. You just sold high and bought low without a single prediction. If instead bonds had surged, you’d do the reverse. The mechanics are boring; the discipline is the point.
Calendar vs. bands: which is better?
Calendar rebalancing means checking on a schedule, say every January, and restoring targets once a year. Band rebalancing means acting only when an asset drifts past a threshold, such as 5 percentage points from target. Research suggests bands are slightly more efficient, since they respond to actual drift rather than the calendar, but the difference is small. Pick whichever you’ll actually follow. Annual calendar rebalancing is the simplest default and beats never rebalancing by a wide margin.
How often to rebalance
Once or twice a year is plenty. More frequent rebalancing adds trading costs and taxes without much benefit. Some investors rebalance on a calendar (every January); others use tolerance bands (rebalance when any asset drifts 5% from target). Either works.
The tax cost of rebalancing
In a taxable account, selling winners to rebalance triggers capital-gains taxes, which is why you should rebalance inside tax-advantaged accounts (IRAs, 401(k)s) first, where trades are tax-free. In taxable accounts, prefer gentler methods: direct new contributions to the lagging asset, or donate appreciated shares to charity instead of selling them. Never let the tax tail wag the allocation dog, but don’t rebalance in taxable when a tax-free account can do the job.
Three rebalancing mistakes
First, never rebalancing at all. Drift is silent, and a portfolio left alone for a decade can end up far riskier than intended. Second, rebalancing too often. Monthly rebalancing adds taxes and trading costs for no meaningful benefit; annual is plenty. Third, rebalancing in a taxable account before using tax-advantaged accounts. Always do the tax-free rebalancing first, then touch taxable only if the allocation still needs work.
Simple rules that work
Keep it mechanical: pick a target allocation, check annually, and rebalance in tax-advantaged accounts first to avoid capital-gains taxes. If you’re building a portfolio from scratch, start with low-cost index funds. They’re ideal for rebalancing because they’re diversified and cheap. Our beginner’s guide shows exactly how to set one up.
You must be logged in to post a comment.