I'm looking into opening a Scottrade account in the future, and was wondering if they pay interest on cash in your brokerage account? Are the rates published anywhere?
Rates fluctuate based upon the federal funds rate.
As a longtime customer of Scottrade I want to say that I'm very happy with it. Now, to answer your question: they do give you a nominal cash interest rate but it is VERY low -- this past month it was 0.01% APYR. The interest that I earned in my Scottrade account in August (31 days) on average credit cash balance of $729.36 was $0.01.
I don't know if or where they publish the rate, but you would get a much better rate from an average savings account. However, you can purchase CDs/bonds/tbills through Scottrade if you want cash/safe investments.
These interest rates are very low. One of the reasons that I prefer E*Trade is because on their on-line savings account the interest rates are several times higher than on ScotTrade margin accounts (currently it's 0.7% on E*Trade, on any amount, IIRC).
The transfers between the accounts on E*Trade are immediate, and they allow using the money for investing immediately even for transfers from outside source. If you can wait a couple of days for the money to arrive before your investment (unless ScotTrade, like E*Trade, allow investing external transfers immediately), you can look at AMEX, ING Direct or Capitol One on-line savings accounts for even higher rates.
Oh, and needless to mention, on-line savings accounts are FDIC insured, I'm not sure if the uninvested deposits on Scottrade are.