An account whereby a brokerage firm may automatically transfer- or sweep- a client’s surplus funds (unused cash) into a specific amount such as a money market fund or other short-term interest-bearing investment. The client need not do anything, while his money is being invested at a certain interest rate (at par with the going market rate) instead of being laid idle in his brokerage account. Some brokers will not automatically transfer a client’s idle funds into a money market fund, and it is left for the client to instruct his broker to have this done.