Do you have a checking account at your brokerage? As this Wall Street Journal article
describes, checking accounts at brokerages like Fidelity, Charles Schwab and TD Ameritrade have been gaining deposits:
The firms' efforts seem to be paying off. Fidelity saw a 40% increase last year in the number of Fidelity Cash Management Accounts, according to the company. Schwab's bank deposits increased about 20% to $61 billion in 2011, according to Kapstone Consultants, a New Jersey-based bank consultancy that analyzed FDIC data at the request of The Wall Street Journal.
Charles Schwab checking used to offer high interest rates, but that's no longer the case. I don't know of any brokerage checking accounts today that offer decent interest rates. However, with interest rates that are so low, that may not be an issue with most people. They may prefer the perks of those checking accounts (free ATMs, free checks, no monthly fees, etc.) and the added simplicity of having their checking account with their brokerage.