In a recent article in this Journal, K. G. L6fgren [1] has developed the theory of intertemporal price discrimination, using the example of a book publisher who sells a high-priced hard-cover edition initially and then later introduces a low-priced paperback edition. The price difference is greater than that justified by cost considerations and is based on the different demand elasticities between the hardcover market (well-to-do and/or eager) and the paperback market. Ldfgren analyzes the managerial problems, in a profit maximizing model, of when to introduce the paperback edition, and the prices and quantities-sold of the two editions. We would like to discuss another example of intertemporal price discrimination, one which differs from Ldfgren's in several respects but which is in the same spirit: Prices vary temporally due to the fact that the firm deliberately exploits the different demand elasticities of various buyer groups ... Our example is an important phenomenon in American retailing, the shortterm sale. This is the practice by which large retailers temporarily reduce prices on certain products for just a short period of time (one day or one week), with great advertising fanfare but virtually no advance notice. Such temporary price reductions are different from other types of such as bait-and-switch sales,2 loss-leader sales,3 sales on slow-moving items which (in hindsight) have been overpriced, and stock-clearance on end-of-season or discontinued items. They also differ from other cases of inter-temporal price differences, such as for vacation resorts and air travel; these other cases,