An investment Account is for medium and long term market players.
A smart investor often uses limit orders to buy and sell. For example, an investor may place an order to buy GE stock at $12 though the price is currently at $13 or below $12. The order can be delayed or executed instantly depending on the brokerage firm.
Usually, most investment account orders are delayed. One can place those orders before or after the markets open and during live markets opening hours.
The smart medium and long term investors always buy or sell at a specific price. Therefore, they are patient and do not worry about the short term fluctuations.
Also, when they want to close a position, that order can be delayed. For example if one buys HP stock at $22, and it rose to $30. Now the market is open, and one wants to sell it profitably, still the order can be delayed except if the broker has the facilities to sell it right away at the current market price $30. It means sometimes that one may not be able to sell it right away at $30 or end up selling it at a lower price.
Please note that some brokers do have the facilities to sell instantly like with the purest trading accounts.