Rebalancing

There are two main rebalancing approaches: Calendar-based rebalancing involves checking and restoring allocations at fixed intervals — monthly, quarterly, or annually. Annual rebalancing is most common for individual investors. Threshold-based rebalancing triggers adjustments when any asset class deviates from its target by a set amount, typically 5% or more (absolute).

Rebalancing can be executed by selling overweight assets and buying underweight ones, or by directing new contributions toward underweight categories. Tax-advantaged accounts (401(k), IRA) are ideal for rebalancing because selling does not trigger capital gains taxes. In taxable accounts, tax-loss harvesting can be combined with rebalancing to offset gains.

Research shows that rebalancing frequency matters less than consistency. Annual rebalancing captures most of the benefit. More frequent rebalancing increases trading costs and taxes without significant improvement. The optimal approach depends on transaction costs, tax implications, and portfolio size.

Rebalancing serves two critical functions: maintaining the intended risk level and systematically enforcing a contrarian discipline. Without rebalancing, a portfolio naturally becomes more aggressive after bull markets (when risk is typically elevated) and more conservative after bear markets (when future returns are typically higher). Rebalancing counteracts this.

Studies show that rebalanced portfolios have lower volatility and comparable or better returns than drifting portfolios over long periods. The benefit is primarily risk reduction — rebalancing keeps portfolios aligned with the investor's risk tolerance and prevents the disastrous outcome of being overexposed to a single asset class before a downturn.