The structure changes without a new decision
Suppose a fictional portfolio of one million roubles has 600,000 in part A and 400,000 in part B. A grows by 20% while B is unchanged. The ending values are 720,000 and 400,000, for a total of 1.12 million. A’s share becomes approximately 64.29% instead of the original 60%.
The change occurred without a deliberate increase in risk. If the original structure had a purpose, the new composition should at least be checked. Arithmetic alone does not prove that a trade is required: the objective, horizon or circumstances may have changed. In that case review the rule first rather than automatically restoring old figures.
Record why the original structure was chosen. “It looked attractive” is not useful at the next deviation. A record of the task, constraints and permitted deviations makes later actions understandable.
Different ways to restore conditional weights
If the educational objective remains unchanged, 60% of 1.12 million is 672,000. The difference from the current 720,000 is 48,000. Without costs or constraints, moving that amount from A to B would restore the original weights. This is arithmetic, not an instruction to trade.
Another route is to contribute 80,000 of new money only to B, increasing the portfolio to 1.2 million while leaving A at 720,000. B’s share then returns to 60%. In practice, the source, timing and availability of a contribution must be checked; free cash cannot be assumed.
Interim cash distributions can also be directed to change the structure. Investor.gov discusses rebalancing through trades or directing new money to other portfolio parts.[9](#source-valuation-allocation) The method should be chosen after considering costs, constraints and tax consequences, not merely the convenience of the formula.
The review rule and the price of action
Composition can be checked on a calendar or when a deviation crosses a predefined boundary. These are different organisational approaches; neither is declared superior here. State what is compared: percentage points, relative deviation or another measure. Without a definition, “exceeds by several percent” can mean different things.
Costs can change the result.[6](#source-valuation-fees) If moving 48,000 has a total cost of 0.5% of the transferred amount, the cost is 240 roubles. Actual tariffs may include separate charges and execution-price differences, so final weights after costs should be recalculated.
Tax consequences depend on jurisdiction, account type and transaction. Do not insert a universal rate merely to complete a spreadsheet. If the consequences are unverified, label that limitation and preserve the documents for a separate calculation.
Behaviour matters more than attractive automation
A common mistake is calling a chase of a recently rising asset “rebalancing.” Another is changing the rule immediately after an unpleasant move without separating new information from emotional reaction. A useful log contains the composition before the decision, the deviation, the reason for action or inaction, expected costs and the information available at the time.
Build in a pause to check data and terms. Do not turn the pause into a promise never to change: a new objective or major event may require revision. But revising the structure and restoring the previous structure should have different records and reasons.
Rebalancing does not guarantee higher returns or remove market risk. Its verifiable result is narrower: the portfolio again follows the announced rule, or the rule was consciously changed. Financial outcomes depend on future events that arithmetic cannot predict.