<h2>ABSTRACT</h2>
<p>If a retailer invests in alternative sourcing for a product otherwise provided by a dominant supplier, it may gain leverage to pressure the supplier into lowering the wholesale price (bargaining effect). The reduced wholesale price, in turn, strengthens the retailer's competitive position, enabling it to capture additional market shares (business-stealing effect). To counter the latter effect, and thus reduce the retailer's incentive to invest in alternative sourcing, the supplier might commit to uniform wholesale pricing. However, we demonstrate that this strategy is unprofitable when retailers are sufficiently differentiated. Instead, if retailers differ in size, supplier profitability is maximized through size-based price discrimination. This might harm consumers. Interestingly, when substitutability is at an intermediate level, supplier and consumer preferences align.</p>