Why are there market makers, where a bargainer has limited information about the reservation prices of other buyers and sellers? What are the conditions such that a bargainer prefers the market maker over direct bilateral or multilateral trade, even if full information about his peers’ reservation prices may be available in direct negotiations? Within Mr. Seemüller’s work, these questions are addressed. He analyses how bargainers determine prices on different platforms, where buyers and sellers reveal their respective offers for a good or a service to each other. A special focus lies upon the distribution of information between the bargaining parties and their inability of precise valuation. Each platform’s efficiency is analysed in deta...