Portfolio Rebalancing: When and How to Adjust

Calendar rebalancing is the simplest approach. You pick a frequency — quarterly, semi-annually, or annually — and rebalance on those dates regardless of how far your allocation has drifted. Annual rebalancing is the most common, and research suggests it captures most of the risk-reduction benefit. The downside: you might rebalance when drift is negligible, triggering unnecessary trades and taxes.

Threshold rebalancing uses trigger bands instead of dates. When any asset class drifts more than a set percentage from its target — typically 5 percentage points — you rebalance. A 60/40 portfolio would trigger a rebalance when stocks hit 65% or drop to 55%. This approach is more responsive to market moves but requires monitoring.

Hybrid rebalancing combines both: check on a schedule, but only trade if drift exceeds a minimum threshold. This is what most financial advisors actually recommend. Check quarterly, but only rebalance if drift is 5% or more. It minimises unnecessary trades while still catching major dislocations.

All three approaches outperform doing nothing over multi-decade horizons. The differences between them are small — what matters is picking one and sticking to it.

In taxable accounts, every rebalance is a potential tax event. Selling winners triggers capital gains, and at current long-term capital gains rates of 0%, 15%, or 20% depending on your bracket, that tax drag compounds over time.

The smartest rebalancing approach for taxable accounts: direct new contributions to underweight asset classes first. If you're investing $1,000 per month and stocks are overweight, route new money entirely to bonds until the allocation corrects. No selling required, no tax hit.

When contributions alone aren't enough, use these techniques in order:

1. Rebalance in tax-advantaged accounts first. Your 401(k) and IRA have no tax consequences for trades. If your total portfolio is overweight equities, sell stocks and buy bonds inside the IRA before touching the taxable account.

2. Harvest losses alongside rebalancing. If any position is underwater, selling it to rebalance does double duty — you restore your target allocation and capture a tax loss to offset gains elsewhere.

3. Use dividends and distributions. Instead of reinvesting dividends into the same fund, redirect them to the underweight asset class.

4. Sell last. Only sell appreciated assets to rebalance if the other methods haven't closed the gap. And when you do, prioritise selling lots with the longest holding period (for long-term capital gains treatment) and the highest cost basis (for smaller gains).

Rebalancing too often. Monthly rebalancing generates more trades, more taxes, and more friction — with almost no improvement in risk-adjusted returns compared to quarterly or annual rebalancing. Transaction costs and tax drag eat whatever marginal benefit you'd get.

Ignoring your full portfolio. If you have a 401(k), an IRA, and a taxable brokerage account, rebalance across all of them as a single portfolio. Many investors rebalance each account separately, which is suboptimal. Your 401(k) might be 80% stocks and your IRA 40% stocks — together they might hit your target, but individually they look wildly off.

Emotional overrides. The whole point of rebalancing is that it's mechanical. If you skip rebalancing because stocks keep going up and you don't want to sell, you've abandoned the discipline. The market will eventually remind you why risk management matters.

Forgetting to rebalance within asset classes. If your equity allocation is split between US and international stocks, drift happens there too. US stocks have massively outperformed international markets for over a decade. Your 70/30 US/international split might be 85/15 by now.