Trailing commissions on mutual funds purchased in a discount brokerage account go to the firm.
Some investment fund managers offer a series of their funds that is designed for Discount/DIY investors. These fund series pay a lower trailing commission than do the traditional full service retail series. However, not all discount brokerage firms offer these series of funds.
If you have questions about trailing commissions or other fees, consider your options and always review documents such as Fund Facts prior to purchasing a fund to ensure you understand the costs and other charges associated with your investment.