Markets are central institutions of Western societies and their main mechanism of coordination; however, we do not know much about their functioning. How are prices formed? By which ways do buyers and sellers meet? What kind of rule are necessary for markets to function? The purpose of this paper is analyze some aspects of market functioning, and to try to isolate mechanism by which this functioning may be determined by diverse institutional forms. A comparison of some markets for perishable goods and some financial and commodity markets allows to identify set of rules controlling their functioning. A preliminary result of this comparison is the characteristics  of the traded good.