T + 3 exists to protect each party; i.e for the correct legalities & checks/balances to be maintained before a credit is cleared via a "contract". It is not a simple transfer of monies, but in effect, a very complex legal transaction with contractual responsibilities from both parties apparent, hence the delay.
By the way, don't do it. It's akin to gambling on credit and the apes that do this, ineviteably lose. Never buy a share with cash that you do not have, unless you have a defintive investment loan to be used as an offset against an asset is my advice and in effect, if using a bank as a traidn platform, they do precisely that.
Casino and the TAB are on the net, in your suburb and in your city. That's for entertainment. Investing is not unless you can gamble what you can afford to lose.
