http://en.wikipedia.org/wiki/Sweep_account

A sweep account is actually a combination of two or more accounts at a bank or financial institution. It is useful in managing a steady cash flow between a cash account used to make scheduled payments, and an investment account where the cash is able to accrue a higher return.
Many banks and financial institutions offer a sweep account service for personal customers and small business owners. It has also become part of the arsenal of services offered by credit card companies.

In a sweep account
A cash account is set up first and a lump sum of money is deposited into that account.
A financial advisor and the client will discuss and determine an average balance that should be kept in this account. Depending on the institution's service programs, this amount may be pre-determined.
Most of the extra cash above the average balance will be invested into a money market, CD, or some other form of investment that can be easily liquidated.
When the balance in the cash account falls below the pre-determined average balance, some of the investment is liquidated and the proceeds get deposited into the cash account, thus maintaining the average balance.

Investment Sweep Account
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Excess funds are automatically moved on a daily basis from your Business Checking (current) Account to your Investment Sweep Account, so your business earns a ...
https://www.northwestsavingsbank.com/b_investmentacct.htm

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Sweep account - conta temporária em que são lançados saldos de caixa originados de outras contas, a serem aplicados em fundos de curto prazo ou em outros instrumentos de curto prazo.
Source: Dicionário de administração de risco financeiro; by Gary L. Gastrineau et Mark P. Kritzman
(this one, in its turn, was translated from the 'Dictionary of Financial Risk Management.'
BMF - Brazil

  I am divulging this, since I deemed useful to improve the learning about the subject.  

  I really hope it doesn´t complicate it more.

  PP.