The odd-lot theory is one of several theories of contrary opinion. In essence, the theory assumes that the common mean is usually wrong and that it is, therefore, advantageous to pursue strategies opposite to his thinking. In order to find out what the common man is doing, statistics on odd-lot trading are gathered. Most odd-lot purchases are made by amateur investors with limited resources – that is, by the common man, who is the small, unsophisticated investor.