Conventional wisdom suggests that domestic manufacturers benefit from cost advantages vis-á-vis their foreign rivals. Tariffs on imported products or exchange rate depreciations are typically expected to raise relative prices of foreign goods and shift residual demands of domestic substitutes outwards. Here we show that these changes in wholesale/manufacturing prices can be offset and even dominated by adjustments in retail markups. Retailers have an incentive to charge the highest markups for low-cost products, and to adjust the markups on these products most actively. Thus, if the procurement costs of some foreign products rises, retailers will shift these cost increases towards the most efficient domestic products thereby mitigating the benefits of a protectionist tariff. We show that this effect can dominate the traditional substitution effect. * We are grateful for comments by Ron Davies, Steve Hamilton and participants of the GIST (Algerho), ETSG (Leuven),