Margin amount

Margin call should be maintained at their desired level. This is like a security deposit. If the balance falls, You have to pay again. There is no profit for them apart from their brokerage fees. This is a marketing strategy I believe. Besides, what is the guarantee that you are also going to get positive returns on intraday? So the trading companies are generous. Top of that, you cannot do trading with your 1/- + 10/-, as I understand all stocks will be above that range. So, you have to deposit more money in order to start trading.