Can new contributions bring a portfolio back to its target mix?

Separate the target from the action

Investor.gov describes rebalancing as restoring a chosen allocation and identifies contributions as one possible method. Its guide also flags transaction costs and tax consequences for consideration. A target is a starting assumption for the worksheet, not evidence that the allocation is appropriate for a particular person.

Use fictional Buckets A and B with $7,000 and $3,000 respectively. The portfolio is $10,000, split 70% and 30%. Stipulate an already chosen target of 60% and 40%. No market movements, fees, taxes, or rounding constraints occur during the exercise.

Case 1: change holdings without new money

At a constant total of $10,000, target amounts are $6,000 in A and $4,000 in B. Moving $1,000 from A to B reaches those amounts. In the worksheet, this is a reduction of A and an increase of B, not new investment growth.

A real transaction could have effects excluded from this arithmetic. The calculation identifies the amount required under the assumptions; it does not instruct the reader to sell anything or determine whether the trade is permitted or sensible.

Case 2: add $1,000 entirely to B

Add a fictional $1,000 contribution to B while leaving A untouched. The new amounts are $7,000 and $4,000, and the total is $11,000. A’s weight is $7,000 ÷ $11,000 = approximately 63.64%; B’s is approximately 36.36%.

The portfolio moved toward the target but did not reach it. Dividing the new B amount by the old $10,000 total would incorrectly report a 40% weight. Every contribution needs a fresh denominator.

Case 3: allocate a $2,500 contribution

Instead add $2,500, with $500 to A and $2,000 to B. Holdings become $7,500 and $5,000, totaling $12,500. Dividing by the new total gives 60% and 40%, exactly matching the stipulated target.

The example also shows why the phrase put everything into the underweight bucket can be incomplete. Adding the entire $2,500 to B would produce $7,000 and $5,500, or 56% and 44%, overshooting the fictional target. The right arithmetic depends on the available contribution amount.

For a practical review card, state when the contribution is available and which holdings the target includes. A planned contribution that has not arrived should not appear in the current weights. Record the current mix and the proposed future mix on separate lines so a reader can tell which amounts already exist.

Method, sources, and limits

All amounts and the 60/40 target are invented, with results checked using decimal arithmetic. Investor.gov’s guide was opened on 26 October 2026. No actual allocation, tax lot, account rule, or rebalancing frequency was evaluated. A portfolio can move away from its target again as values change; reaching a mix once does not guarantee any outcome. This worksheet compares funding mechanics rather than recommending a target or a transaction.