Chapter 3 painted the broad canvas and described OTC markets. Here the focus is on formal markets organized into exchanges, the other end of the spectrum. Their birth, when it is organic and not administered by authorities, is rather stereotypical. A group of traders get into the habit of coming together in a place and at a time to do business and exchange information. The concentration in space and time makes it easier to ﬁnd a counterpart, and the familiar faces make it possible to separate respectable from unscrupulous individuals. The place offers some shelter against weather, like a buttonwood tree, and possibly also refreshments, like a coffee house. The possibility of making money attracts all kinds of unwanted elements, however, and at some point in time their presence becomes sufﬁciently disturbing to prompt the creation of an organized club able to select its members, and the transfer of activity into private premises closed to outsiders.