Supplier enchroachment and consumer welfare: Upstream firm's opportunism and multichannel distribution

I revisit supplier encroachment under the framework of a two-part tariff contract. When a monopoly manufacturer supplies competing retailers and each retailer's contracting process is unobservable to the rival, the retailer's lack of knowledge vis-à-vis its rival's contract may undermine the manufacturer's commitment power, which prevents the manufacturer from achieving optimal profit. I demonstrate that when the manufacturer directly supplies the resale market, it can use the direct channel as a commitment tool and thus restore its market power. Even though the manufacturer's encroachment creates more competitors in the resale market, the resultant higher wholesale prices aggravate double marginalization, which may reduce consumer welfare. This result holds even when the manufacturer is very efficient in direct selling.