Rebalancing Strategies

Rebalancing is the periodic adjustment of a portfolio back to its target allocation. Without rebalancing, a portfolio drifts: stocks compound faster than bonds in good times, so a 70/30 allocation can become 85/15 in a multi-year bull market. The drift is silent risk-taking. Rebalancing is the discipline that keeps the portfolio aligned with the policy that was set during calm conditions.

This page is about when to rebalance, how, and the practical tricks that minimize cost and tax friction.

Why rebalance at all

The case for rebalancing has three components:

Risk control: an unrebalanced portfolio drifts toward the highest-return asset, which is also typically the highest-risk asset. Drift increases your portfolio's risk over time without your decision.
Disciplined buy-low / sell-high: rebalancing forces you to sell what has outperformed and buy what has underperformed. Counter-intuitive in the moment, helpful over decades.
Adherence to the plan: the IPS sets the allocation you intended; rebalancing keeps the portfolio actually at that allocation.

The case against frequent rebalancing:

Transaction costs (less relevant now with $0 commissions)
Tax costs in taxable accounts (capital gains realized when selling)
Loss of momentum — the outperforming asset class often continues outperforming for some period

The honest synthesis: rebalance, but not constantly. The right cadence is once or twice a year for most portfolios.

The two main approaches

Calendar rebalancing

Rebalance on a fixed schedule — typically annually or semi-annually. Common dates: January 1, July 1, or birthday/anniversary.

Strengths:

Simple, predictable
Easy to integrate with annual portfolio review
Forces action even when drift is moderate

Weaknesses:

May rebalance unnecessarily when drift is minimal
Misses opportunities for rebalancing during major market moves between scheduled dates

Threshold rebalancing

Rebalance only when an asset class drifts more than a fixed percentage (typically 5%) from its target.

Strengths:

Avoids unnecessary trades when drift is small
Captures rebalancing benefits during major market moves
Lower turnover

Weaknesses:

Requires monitoring (or alerts)
May miss rebalancing if no threshold is crossed for years
Multiple thresholds across asset classes can produce frequent small trades

Hybrid approach

Check on a fixed schedule (say, January 1 and July 1) and rebalance only if any asset class is more than 5% from target. This combines the discipline of calendar with the efficiency of threshold.

For most household portfolios, the hybrid is the right answer.

How to rebalance with minimal tax cost

Rebalancing in a taxable account by selling appreciated assets generates capital-gains tax. There are several ways to minimize this.

1. Use new contributions for rebalancing

If your portfolio is 75% stocks against a 70% target, direct your next several monthly contributions exclusively to bonds until the allocation moves back. No selling, no tax.

This works for accumulation-phase portfolios. As the portfolio gets larger relative to monthly contributions, the technique becomes less effective.

2. Rebalance in tax-deferred accounts first

If you have both a taxable brokerage and a 401(k)/IRA, rebalance within the tax-deferred account first. Selling within tax-deferred accounts has no tax impact.

3. Rebalance during withdrawals (in retirement)

In retirement, withdrawals can be drawn from the over-target asset class, naturally rebalancing without forced sales beyond the withdrawal.

4. Tax-loss harvesting during rebalancing

If rebalancing creates a sale, look for offsetting losses elsewhere in the portfolio. See TaxLossHarvesting.

5. Use dividends and distributions

Rather than reinvesting dividends in the same fund, direct them to the underweighted asset class.

A specific rebalancing routine

A practical annual routine:

Set a date: pick January 1 or your birthday. Same date every year.
Pull current allocation: total each asset class across all accounts.
Compare to target: identify any asset class more than 5% off target.
If within thresholds: do nothing. Document and move on.
If a threshold is crossed: rebalance, preferring tax-deferred accounts and using new contributions for direction-only adjustments.
Document: note the date, the action taken, and the rationale.

This is 30–60 minutes per year for most portfolios. Less time than most people spend on a single financial decision; more value than most.

Glide path: changing allocation over time

For most investors, the target allocation should evolve as horizon shortens. The mechanism: as you age, you have less time to recover from a market drop, so the allocation shifts toward bonds.

A standard glide path:

Age	Stocks	Bonds	Notes
25	90%	10%	Aggressive accumulation
35	85%	15%	Maintain aggressiveness
45	80%	20%	Begin gradual shift
55	70%	30%	Pre-retirement
65	60%	40%	Retirement transition
75	50%	50%	Mid-retirement
85+	40%	60%	Late retirement

This is one defensible glide path; many alternatives exist. Target-date funds use specific paths their managers have selected. See TargetDateFunds for the all-in-one solution that handles this automatically.

The glide path is implemented through rebalancing — your annual target shifts a percentage point or two each year, and rebalancing brings the portfolio toward the new target.

Common failure patterns

Not rebalancing at all. The portfolio drifts; risk increases silently.
Rebalancing too often. Monthly or quarterly produces transaction friction without meaningful risk improvement.
Selling everything during a downturn. Rebalancing into bonds during a 30% drop is the opposite of what the discipline calls for.
Forgetting to rebalance in retirement. Just because contributions stopped does not mean rebalancing should.
Rebalancing in taxable accounts first. The tax cost is often substantial; tax-deferred rebalancing is usually equivalent and free.
Skipping the IPS-prescribed rebalancing during euphoria. The hardest moments to rebalance are the ones where the discipline matters most.