Abstract:With the rise of e-commerce, more and more firms are experimenting with online auctions, among which eBay. corn has achieved the great success. Based on eBay, this paper studies an online English auction with proxy bidding where customers arrive one after another and the seller can either set a reserve price or not. After describing the process of the online auction, it is shown that the truthful and early bidding is dominant strategy for bidders if their valuations on the item are independent and private. Then, we compare this strategy with the last-minute bid- ding strategy presented in the literature for the case of interdependent valuations, and we interpret some bidding behavior in practice