A higher auction resale price can still produce a loss

A realized gain on an auction purchase is the excess of net disposal proceeds over the owner’s acquisition outlay and included holding costs. An increase in hammer price is a different measurement.

Hammer price is the winning bid. The buyer invoice adds the buyer’s premium and other applicable charges. Seller proceeds deduct the seller’s charges from the amount attributable to the sale. Each number describes a different side of the transaction.

The auction round trip

Take a purchase hammer price of 100 and a buyer’s premium of 20. The buyer spends 120 before any other charges. If a later sale hammers at 120 and the seller pays charges of 10% of that hammer, the owner receives 108. The hammer price rose by 20%; the owner lost 12 on the stated cash flows.

For these constructed terms, break-even requires a later hammer of 120 divided by 0.9, or approximately 133.33. The required hammer-price increase is approximately one third, even with no holding costs.

This example assumes a fixed initial outlay and a proportional seller charge. It excludes taxes, insurance, storage, transport, financing, and changes in currency value. Adding a cost changes the break-even amount; replacing the seller’s charge structure changes the equation.

Premium schedules change the comparison

Buyer’s premiums need not apply one percentage to the entire hammer price. A marginal schedule applies each rate only within its specified band. Category-specific schedules also mean that two objects with the same hammer price can produce different buyer invoices within one auction house.

The applicable rate belongs to the house, sale location, collecting category, and date. A result labelled only “sale price” is incomplete for a return calculation until its treatment of premium and other charges is known.

An appraisal is another basis of value

An appraisal does not supply the missing cash flows. For US charitable-contribution purposes, a qualified appraisal must identify its valuation method and supporting basis under the applicable standards. That requirement establishes the purpose and construction of a valuation; it does not turn the appraised amount into the seller’s proceeds.

An auction comparison therefore holds the accounting basis constant before comparing prices. Purchase outlay is compared with net disposal proceeds. Hammer is compared with hammer only when the question is hammer-price movement. Neither comparison answers the other question without the intervening charges.