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Rebalancing is the least popular discipline in wealth management, because it asks you to do the opposite of what feels right: trim what has performed and add to what has not.
The discomfort comes from framing it as a return decision. It is not. It is a risk decision, and once seen that way it stops feeling like self-sabotage.
What drift actually does
A portfolio built at a deliberate allocation does not stay there. Strong performance in one asset increases its share of the total — which means the portfolio’s overall risk rises without anyone choosing to raise it.
The arithmetic is unglamorous. Take an illustrative portfolio of 60 percent equity and 40 percent debt. If equities rise by half over a few years while debt earns a modest single-digit return, the mix ends up near 68/32 without a single trade. Vanguard’s rebalancing research, using data from 1926 to 2018, found that a 60/40 portfolio left alone averaged an 85 percent equity allocation over the period, with correspondingly higher volatility.
The uncomfortable part is the timing. Drift is largest after a sustained run, which is precisely when conviction is highest and trimming feels most wrong. The portfolio has become more aggressive at the moment the investor has become most confident. Those two things compound each other.
Restoring the decision you actually made
Rebalancing returns the portfolio to the risk level you chose when you were thinking clearly, rather than the one recent performance has drifted you into.
Whether it helps or hurts returns in any given period is genuinely unknowable in advance. Vanguard’s own conclusion is that the purpose of rebalancing is to maintain a portfolio’s risk and return characteristics, not to maximise returns. In a market that trends upward for years, the un-rebalanced portfolio will usually finish ahead — and will have carried far more risk to get there.
What rebalancing does reliably is keep the portfolio’s risk close to the level the investor can actually tolerate — and tolerance is what determines whether someone stays invested through a difficult stretch. A portfolio abandoned at the bottom of a drawdown has no long-term return at all. Rebalancing is the maintenance that keeps the investor in the seat.
There is a quieter benefit too. A portfolio that is regularly brought back to target is a portfolio someone is regularly looking at, against a written standard. Most drift goes unnoticed not because it is small but because nobody is measuring it.
How often should you rebalance a portfolio?
Less often than most people assume, and on a rule rather than a feeling.
There are two types of trigger. Calendar rebalancing reviews the portfolio at a fixed interval — quarterly, half-yearly, annually — and restores the target whatever the drift. Threshold rebalancing ignores the calendar and acts only when an allocation moves outside a defined band, say five percentage points from target.
Vanguard tested combinations of monitoring frequency and threshold over 92 years and found that no specific threshold or frequency consistently outperformed the others. A monthly check with a zero tolerance band rebalanced more than 1,100 times; an annual check with a ten-point band rebalanced 14 times; both produced almost the same return and risk. The finding that mattered was different: any systematic rule beat not rebalancing at all. Frequency is secondary. Having a rule is not.
Calendar versus threshold, in practice
Each trigger has a characteristic failure. A pure calendar rule can leave a portfolio badly drifted for months after a sharp move, and can trade when nothing has changed. A pure threshold rule requires continuous monitoring and, in a volatile year, can trigger repeatedly at real cost.
Most disciplined processes combine them: monitor on a calendar, act only if a band has been breached. Half-yearly or annual monitoring with a band of around five percentage points is a common and defensible starting point; the band should be wider for volatile assets and narrower for the core holdings that define the portfolio’s risk.
The trigger is less important than two properties. It must be written down before the drift happens, and it must not include a clause that says “unless the market feels strong.” Every investor who has one of those clauses uses it.
Bands also need to be set on the allocation that carries the risk. A five-point band on a 60 percent equity target is a meaningful guardrail; the same band on a 5 percent satellite holding is a rule that will never fire. Set the band in proportion to the position, and to how much that position can move the whole.
What rebalancing costs in India
The main cost of rebalancing a taxable portfolio is tax. Under the Union Budget 2024–25, gains on listed equity and equity-oriented funds held twelve months or less are taxed at 20 percent; gains on holdings above twelve months are taxed at 12.5 percent, with the first ₹1.25 lakh of long-term gains each year exempt. These rates remain in force in 2026. Many funds also charge an exit load on units redeemed within a set period.
Three tactics reduce the drag without abandoning the discipline. Direct new money to the underweight asset first — an ongoing SIP into whichever side has lagged rebalances without selling anything. When a sale is needed, prefer units past the twelve-month mark and use the annual exemption deliberately. And for part of the equity-debt mix, a hybrid or balanced fund rebalances inside the fund, which is not a redemption by the investor.
Tax makes the rule slower and more careful. It does not make it optional.
Making it mechanical
The practical answer is to remove the judgement from the moment. Either a calendar trigger — reviewed on a set schedule regardless of how markets feel — or a threshold trigger, acting when an allocation moves beyond a defined band.
Both work. What does not work is rebalancing when it feels comfortable, because it rarely does at the point it matters most. After a strong run, trimming feels like leaving money on the table. After a fall, buying feels like throwing good money after bad. The rule exists precisely so that neither feeling gets a vote.
Write the target allocation, the bands, the review dates and the tax rules of thumb on one page. Then the review is a comparison against that page, not a debate about the market.
The decision is the allocation, not the trade
Rebalancing looks like a series of trades. It is really the enforcement of one decision — the allocation — made once, when the investor was calm, informed and thinking about their own life rather than the last quarter’s returns.
Every rebalancing trade that feels wrong is a measure of how far the market has moved the portfolio from that decision. Treating it as a risk decision keeps the question honest: not “will this make more money?” but “is this still the portfolio I chose to hold?”
If the answer is no because your life has changed — a shorter horizon, a different goal, a new tolerance for loss — then the allocation itself should be revisited, deliberately and on paper. If the answer is no only because the market has been kind to one asset, the allocation has not changed. The portfolio has. Rebalancing is how you tell the two apart, and how you make sure the market does not get to rewrite the plan on your behalf.
This article is part of our guide, How to Build a Resilient Portfolio.
