Abstract: Recent years have witnessed the development of electronic commerce. A large number of manufacturers have transferred the selling mode from the traditional wholesale mode to the online platform selling mode through a platform such as tmall.com. Under the traditional wholesale mode, the retailer buys the products from the manufacturer and then sells them to the consumers. However, under the online platform selling mode, the platform just provides the service for the manufacturers' selling products and keeps a percentage of the sales revenue. The platform acquires rich market data about sales and consumers, and thus has more accurate demand information than the manufacturers. How to share the demand information strategically in online selling mode is an interesting research question. On the other hand, there often are several competing manufacturers (e.g., different brand manufacturers) that produce the similar products and sell them through a common online platform. In the paper, the information sharing problem is studied based on the approach of game theory with incomplete information, in which the platform firstly offers the information contracting and then the manufacturers determine to accept the offer or not. Our research contributes to the literature in considering the information sharing strategies in online selling mode. The extant researches revealed that sharing information will benefit the firms by earning more profit. However, our analytical results show that when the percentage of commission is large and the economy of scale is high, sharing information may not bring more profits for the platform. When the production is economy of scale, the manufacturer who is uninformed of the demand information, acting as a free rider, may benefit from the behavior that the competing manufacturer acquires the demand information; whereas the production is diseconomy of scale, the uninformed manufacturer will be hurt by such behavior. And the more accurate the information is, the more profit acquiring information will bring.Moreover, our numerical analysis reveals that the pricing of the demand information data decreases in the competing intensity between the manufacturers, whereas the increment of the manufacturer's expected profit resulting from the knowledge of demand information increases in the intensity. And if the platform keeps more percentage of the sales revenue, the value of the demand information will be reduced.

Key words: information sharing, online platform, competition, Bayes equilibrium