Rebalancing Your Portfolio

Once a target asset allocation is set — say, 70% equity and 30% debt — market movements will inevitably cause the actual proportions to drift away from that target over time. If equities rally strongly for two years while debt returns stay flat, that same portfolio might drift to 80% equity and 20% debt purely through price appreciation, without the investor actively doing anything. Rebalancing is the periodic process of realigning a portfolio back to its intended target allocation.

Mechanically, rebalancing means selling a portion of whatever has grown to be overweight and buying more of whatever has become underweight, restoring the original target percentages. In the example above, that would mean selling some equity holdings and buying more debt instruments to bring the mix back from 80/20 toward the original 70/30 target.

This process has a valuable, almost counterintuitive side effect: because rebalancing forces selling some of what has recently risen (become overweight) and buying more of what has recently underperformed (become underweight), it systematically enforces a version of "buy low, sell high" discipline, without requiring any market prediction at all — simply following the mechanical rule of returning to target percentages accomplishes this automatically.

Most financial planners suggest rebalancing on a fixed schedule — annually is common — or when an asset class's actual weight drifts beyond a certain threshold from its target, commonly 5 percentage points. Rebalancing too frequently can rack up unnecessary transaction costs and, in a taxable account, trigger capital gains tax on assets sold prematurely; rebalancing too infrequently allows a portfolio's actual risk level to drift meaningfully away from what was originally intended, sometimes without the investor even realizing how much their risk exposure has changed.

Combined with the earlier lessons on risk tolerance, time horizon and diversification, rebalancing completes the practical toolkit of asset allocation: decide the right mix for your goals, diversify properly within each piece of that mix, and periodically bring the portfolio back to that intended mix as markets inevitably push it out of alignment.