[S]uppose that a dominant firm produces goods A and B at a cost of $5 and $7, respectively. It sells the two goods separately for $10 each per unit but offers a 20% discount to anyone who will take a bundle of one A good and one B good. Note that this discounted price, $16, is well above the firm's costs, which are $12. However, a rival sells only B, for which its production costs are also $7. If a customer wants the rival's B good it loses the discount from the dominant firm on the A good. As a result, the customer must pay $10 for the dominant firm's A, and at least $7, the cost price, for the rival firm's B. The rival will be unable to capture the sale of B even though it is equally efficient, in the sense that its production costs for B are the same as those faced by the dominant firm.Hovenkamp, supra at 1229.
