Product line competition and price promotions

Besides its familiar demand-redistribution effect, price promotion by a multi-product firm creates cannibalization, as lowering the price of one variety may erode the profits of its other varieties. We study endogenous product line selection and price promotions in a duopoly. In equilibrium, the ex ante symmetric firms may offer asymmetric product lines with unequal length. The two-product firm is more profitable. The single-product firm offers a larger mean discount and promotes more (less) frequently than its competitor when the former’s unit cost is relatively low (high).