Guess I should answer my own question now that I know the answer in case someone else is looking for the same info.
Firstrade's automatic sweep money market fumd current interest rate is 1.98%. And that's the only choice they have. No other MM fund is available. Your acct has to be 10K+ before you can activate this MM fund feature (no fee involved). They seem not to be overly eager about setting up this feature for users which is understandable. If users don't use it, Firstrade makes an extra 1.98%.
