This cash account requires trading with settled funds. Available Funds under real-time trades shows settled funds while Money Market Balance reflects all cash in the account, including unsettled. Cash is available from a sale 3 market days after the sell.
(What is the settlement date? The settlement date is 3 market days after the trade date (1 market day for options and mutual fund trades) and is the point by which securities must be exchanged for payment. Any assets being traded must be available in your ShareBuilder account at the time a transaction occurs.
Until the settlement date has been reached, the assets gained from a trade – either shares of a security or cash – cannot be transferred or distributed from a ShareBuilder account. You can, however, sell recently-purchased shares or use the proceeds of a sale for a purchase before the settlement date has been reached.
ShareBuilder allows you to reinvest funds from recent stock sales with the understanding that you will not sell the newly purchased shares until three days after the first stock was sold. Regulation T of the Federal Reserve Board requires that stock purchased in a cash account must be paid for in full prior to its sale. Failure to comply with these rules is known as "freeriding" and is not permitted. )
ING Sharebuilder쪽에서는 Margin account를 열면 여러번 가능하다고 하는데,