The Sunk Cost Trap In A Losing Position

A position that has fallen presents a question about the future, but it is routinely answered with information about the past. That substitution has a name and a reliable pattern.

What the decision actually is

The relevant question is whether the capital currently tied up in a holding would be better placed there or somewhere else, given what is known now.

The purchase price does not appear in that question. It is a historical fact about a transaction that has already settled and cannot be undone by any subsequent choice.

Nonetheless the purchase price is where attention goes, and holdings are commonly described as being down rather than as being worth what they are worth.

Why past cost feels binding

Abandoning something invested in feels like admitting the original commitment was mistaken, and that admission carries a cost that continuing appears to postpone.

Continuing preserves the possibility that the earlier decision will eventually be vindicated, which keeps the question open rather than settling it unfavorably.

Effort spent researching a position strengthens the effect. The work becomes part of what would be forfeited, even though the work is equally unrecoverable.

How it appears in portfolios

The clearest sign is a holding that would not be purchased today at its current price but is nonetheless retained without a stated reason.

Another sign is adding to a falling position to reduce the average purchase price, when the reason offered is the average rather than the case for the asset.

Positions inherited from a former employer or a previous strategy often persist for similar reasons, held by history rather than by any current judgment.

The test that isolates the question

The standard reframing asks whether, holding cash instead, the same amount would be used to buy this position today.

If not, the position is being held because of its history. If so, the holding is justified on present grounds and the purchase price was never relevant.

The test is not a recommendation to trade. It separates the reason for holding from the story about how the holding arose, which is all it is designed to do.

Why the effect strengthens with size

Larger commitments produce stronger attachment, so the positions most in need of clear thinking are the ones where clarity is hardest to reach.

Written notes made at purchase help, because they record the original reasoning and allow a later comparison against what has actually occurred.

Where a decision also carries consequences that depend on the account or on individual circumstances, those are questions for a qualified professional rather than a general principle.