Selling at a loss is a practical way of shifting products that have failed to sell.  Retailers find themselves all the time with stock that they need to unload, that nobody is buying. This is especially a concern with items that have a sell-by date after which they may not be sold and so become worthless. In such a situation, selling below cost price is economically rational, as it means that the retailer realises some money on their stock rather than none at all. Visit any open-air market at 3.00 p.m. and you will see traders slashing the prices of unsold perishable goods for just this reason. If a retailer is going to sell an item below price level, it might as well use that item as a marketing device. Can you imagine the same market trader slashing his prices, but not shouting them to passersby? Sometimes retailers need to sell items below the price level, and they should be allowed to market them cleverly in order to make up for some of the loss in revenue.