Portfolio rebalancing when one holding falls 10 percent

What rebalancing actually is

Rebalancing returns a portfolio to its written target weights. It carries out a decision made earlier, before any holding was down and before judgment was under pressure.

Two triggers do this job. A serious portfolio publishes which one it runs on. A calendar trigger acts on a fixed date, monthly, quarterly or yearly, whatever the weights are doing that day. A threshold trigger, also called a band, lets weights drift. It acts only once a holding moves past a stated percentage from its target. Calendar rebalancing and threshold rebalancing answer two different questions. One asks whether the date has arrived. The other asks whether the drift has gone too far.

A ten percent fall in a holding's value does not automatically fire either rule. Under a calendar rule, the size of the fall is irrelevant. Only the date matters. Under a band rule, the fall in value matters less than what it does to that holding's share of the whole portfolio, usually a smaller number.

The arithmetic of one holding down ten percent

Take a portfolio of one crore rupees split by target weight: fifty lakh in equity, twenty lakh in crypto, fifteen lakh in gold, fifteen lakh in debt. Equity then falls ten percent in value, from fifty lakh to forty five lakh. The other three sleeves hold their value.

The portfolio's total is now ninety five lakh. Equity's actual share has moved from fifty percent to 47.4 percent, a drift of 2.6 percentage points from target. Gold, crypto and debt keep the same rupee value each, now a slightly larger share of a smaller total than their targets called for.

A band with a five percentage point threshold, the kind published examples use, would not fire yet. A drift of 2.6 points sits inside that band, so the position runs unchanged. A calendar rebalance due on this date fires regardless of the band, and restores every sleeve to its original percentage of the new, smaller total.

Equity's target on ninety five lakh works out to 47.5 lakh. It holds forty five lakh, a shortfall of 2.5 lakh. Gold's target on the new total is 14.25 lakh against an actual 15 lakh, an excess of 75,000 rupees. Crypto's target is 19 lakh against an actual 20 lakh, an excess of 1 lakh. Debt's target is 14.25 lakh against an actual 15 lakh, an excess of 75,000 rupees. The three excesses add up to exactly the 2.5 lakh equity needs. The rule sells 75,000 from gold, 1 lakh from crypto and 75,000 from debt, and uses the combined 2.5 lakh to buy equity back to target.

Nothing here assumes equity recovers. Nothing here is a forecast. The arithmetic restores a written ratio, and what the ratio does next stays unknown to the rule and to the investor alike.

Why the rule gets written before the fall

A rule exists on paper because a decision made under pressure and a decision made in advance are rarely the same decision. Gobind Daryanani's 2007 study in the Journal of Financial Planning tested rolling five year periods from 1992 to 2004. A threshold set near 20 percent of a holding's own target weight produced the best result among the bands tested. Tighter bands moved too often. Wider bands missed the point of rebalancing altogether. The finding is Michael Kitces's, published on kitces.com as "Optimal Rebalancing: Time Horizons Vs Tolerance Bands." First posted 4 May 2016, updated 26 March 2020. It cites Daryanani's 2007 study in the Journal of Financial Planning.

The same piece cites Vanguard research on a 60/40 portfolio. Rebalancing more often than annually, monthly or quarterly, produced no meaningful gain in long run risk or return, and mainly added transaction costs. Neither study says one specific number suits every portfolio. Both say the number gets picked once, in writing, before any specific holding is down ten percent and the temptation runs high.

What a rebalance costs

Every rebalancing move is a sale on one side and a purchase on the other. Both sides carry whatever fee or spread the platform charges on a transaction. For a directly held portfolio, a regular account of stocks bought and sold, that sale is usually the investor's own taxable event, taxed on whatever gain or loss it realises.

Inside a Qatobit QSI index, only this much is documented. A monthly rebalance inside an index is not the investor's own taxable event. The rebalancing transactions run inside the basket, handled there by the platform's own accounting. The statutory transfer test that applies to an investor's own sale does not apply to the index moving its own weights each month. Inside the basket, a loss on one asset offsets a gain on another before the investor sees either number. That works because the taxable event is the sale of the basket, rather than the sale of each asset inside it. Someone holding the same assets directly gets none of that offset. Every winner there is taxed on its own, and every loser sits stranded on its own.

What an index does so the holder does not have to

Qatobit runs four QSI Crypto Indices, each designed and rebalanced by Qatobit on a documented, published methodology, monthly. The rebalance itself carries a 0.35 percent fee on the transaction. There is no annual management fee, and there is no charge for leaving a basket at any point. A holder who wants the discipline of a calendar rebalance, without writing the bands, tracking the drift or placing the transactions each month, has an option. They can have Qatobit run that calendar instead, on a published schedule rather than a private one.

No index here is claimed to outperform another, and none of this promises what any index returns. What differs is who carries out the rule: the investor, by hand, or the index, on its published calendar.

What one index's own bad year shows about correlation

The Nifty 50 closed at 23,398.10 on 11 September 2026, down 0.34 percent on the day (livemint.com market dashboard, read 15 September 2026). That level sits about 11.3 percent below the index's own record close of 26,373.20 on 5 January 2026. The road between the two was not a straight line. A near 16 percent slide took it to 22,182.55 by 2 April 2026. A partial recovery followed, and it has not closed the gap (Univest, "Nifty 50 Prediction for 2026," updated 12 June 2026, figures re-read 15 September 2026).

A fifty stock index behaves like one holding when a broad risk off move hits, because most of its constituents fall together. That is exactly why an index can lose more than ten percent of its value in a matter of months, with no single company failing. A portfolio that treats Indian equity as one sleeve is treating fifty correlated names as one position. The same ten percent fall that reads as one bad line in a portfolio statement is, underneath, dozens of stocks moving as a single block. The rule that rebalances a sleeve does not need to know why the block moved. It needs only the sleeve's own weight against the target written down before the block moved at all.

A published methodology is what what-is-a-crypto-index gives an index in place of a fund manager's discretion. The same discipline shows up in how a crypto index rebalances during a market crash: the schedule does not change because the fall was large.

A portfolio's written rule is the one part of this decision that existed before the fall did. The question worth asking about the next ten percent move, in whichever sleeve, is not what the market does next. It is whether a rule is already written down to answer it.

Frequently asked questions

Does rebalancing mean selling winners?

Usually, yes. A calendar or band rule sells the sleeve that grew past its target weight and buys the sleeve that fell below target. In practice that trims what performed well and adds to what performed poorly, on schedule rather than on conviction.

How often should a portfolio be rebalanced?

No single frequency suits every portfolio. Research on bands has found a threshold near 20 percent of a holding's own target weight works well across long historical periods. A calendar cadence from monthly to annual made little measurable difference to risk or return on its own. What matters is that one rule gets chosen and published.

What is a rebalancing band?

A rebalancing band, or threshold, is a stated percentage a holding may drift from its target weight before a rule fires. A holding inside its band is left alone, however its value has moved. A holding outside its band gets moved back toward target, regardless of the calendar date.

Does a rebalance inside a Qatobit index trigger tax for the investor?

No. A monthly rebalance inside a QSI index runs inside the basket and is not the investor's own taxable event. The investor's taxable event is their own sale or redemption of the basket, whenever they choose to exit.

What happens if a portfolio is never rebalanced?

Weights drift toward whatever has performed best. The portfolio slowly turns into a bet on its own recent winners rather than the mix first chosen. Nothing forces a correction. The portfolio simply carries more risk in fewer places than the investor decided on when the weights were first set.

Crypto investments are subject to market risk. Not financial advice.