Missed Sales and the Pricing of Ancillary Goods*
研究了企业为何有时将附加商品定价低于成本（如免运费），以促进基础商品销售，并分析了透明度法规和价格上限对福利的影响。
Firms often sell a basic good as well as ancillary ones. Hold-up concerns have led to ancillary good regulations such as transparency and price caps. The hold-up narrative, however, runs counter to evidence in many retail settings where ancillary good prices are set below cost (e.g. free shipping, or limited card surcharging in countries where the “no-surcharge rule” was lifted). We argue that the key to unifying these conflicting narratives is that the seller may absorb partly or fully the ancillary good’s cost so as not to miss sales on the basic good. A supplier with market power on the ancillary good market then takes advantage of cost absorption and jacks up its wholesale price. Hold-ups occur only when consumers are initially uninformed or naïve about the drip price and shopping costs are high. The price of the basic good then acts as a signal of the drip price, since a high markup on the basic good makes the firm more wary of missed sales. Regardless of whether consumers are informed, uninformed-but-rational, or naïve, mandating price transparency and banning loss-making on the ancillary good leads to (i) an efficient consumption of the ancillary good, and (ii) a reduction of its wholesale price, generating strict welfare gains.