Market transparency refers to the level of current trade information revealed to participants by market makers. This paper analyzes the effect of market transparency on the outcomes of posted-offer style Business-to-Business e-commerce markets. First, increasing market transparency improves the price-tracking ability of sellers, and results in higher efficiency. However, revelation of quantity information on transactions is not very crucial as opposed to price information. Second, although sellers extract significantly higher surplus (profit) than buyers can do in a posted-offer market, the difference vanishes with increasing market transparency. Lastly, sellers in posted-offer markets respond poorly to external demand shocks. Interestingly, the poor price-tracking performance of sellers hurts buyers more. In other words, seller profits are much less sensitive to demand shocks as compared to buyer surpluses.