Interest on Your Brokerage Accounts
You are likely to always have some cash in your brokerage account. Some brokerages will offer 3-5% interest on this money, while others won't offer you a thing. Phone or email the brokerage to find out what they offer. In fact, this is a good question to ask their customer service!
Source: http://www.investopedia.com/articles/00/112100.asp