The paper empirically studies why the sellers of identical commodities adopt different auction formats in the online auction, and the consequences thereof. We postulate that the sellers adopt different auction formats because of the differences in their experience and the number of items they have. We first use these two characteristics to endogeneize the seller's choice between three auction formats: fixed-price, buy-it-now (BIN), and pure auctions. We then estimate the differences in sales rate, transaction price, and sale duration between the three formats. We find that the fixed-price auction results in the highest transaction price and the lowest sale rate, while the pure auction is just the opposite, with the BIN auction falling in between. These results strongly suggest that there is a tradeoff between price and sale probability in adopting different formats of auctions. * We thank Ching-I Huang and Jong-Rong Chen for their useful comments and suggestions.