The firms that hire the specialists to represent companies listed on certain exchanges. Companies listed on certain exchanges will interview employees of the specialist firms, seeking out suitable people to represent them by holding inventories of the companies' stocks.

In the 1980s, there were upwards of 50 specialist firms, and most were family-owned businesses. In 2008 there were 10, due to decades of mergers and acquisitions; seven of them being stock specialist firms, while the other 3 specializing in ETFs.