Contra Transaction
Contra transaction is a procedure of buying and selling stocks before the payment date. The broker pays trader on contra profit and seller pays the broker on contra loss.
T+3 Situations:
T day = Trading day
Example:
T = Friday
T1 = Monday
T2 = Tuesday
T3 = Wednesday
Contra transaction can be done before T3, 12.30pm. Broker will force sell the outstanding share if the trader failed to make a payment and sell their share within this period.
* Market day is day that exchange open for trading. If on Tuesday is a public holiday and exchange close, T3 will be Thursday.


