Some stock brokerage firms have offered temporary “specials” where they don‘t earn commissions on stock trades and a few (e.g., Robinhood Financial, discussed in the chapter) have made zero stock trading commissions permanent part of their business model. In fact, most stock brokerage firms earn less than 40% of their revenue from commissions. How can such firms realize revenues from their clients or elsewhere if they don’t produce stock-trading commissions?