These are accounts at brokerage firms used to hold temporary cash balances.  They are used for client deposits and withdrawals.  Buys and sells and dividends usually flow through the accounts.

Mutual Fund accounts held at the fund company will have an Account Daily Cash Balance, but it will not normally appear on reports or on the View Screens.  Unless your mutual fund actually uses a cash balance account, we don't recommend that you manually set flows to use them. Do not confuse Cash Balance Accounts with Money Markets held at the fund company.  A money market is often treated as just another fund in the account.

See Also

Account Daily Cash Balance

Reports And The Cash Balance Account