Parttime,
Today brokers on futures turnover charge between 230 to 650 per crore in terms of transaction + clearing charges. So yes we are not lowest, but we around 250 from the lowest and around Rs 100 per crore from the average higher..
If you are paying Rs 150/crore extra, doesn't matter if it is intraday or overnight, it is Rs 150 itself. If you buy and sell 1 crore then the turnover is 2 crores and not 1 crore. So the example you have given is not really right.
What you need to understand is that it is futures turnover that you are talking about and this contributes only around 15 to 20% of exchange turnover and most of the contribution to futures turnover comes from institutions rather than retail.
Why we charge extra have explained a few times already. Options turnover is what contributes 70% volume on the exchanges and what retail is actively trading today. In options, the turnover charges hardly makes any difference and we are around the average that is charged by industry.
Btw, I guess had too much time on my hand today, spent time writing unnecessary blah blah blah posts once too many times..
.. Sorry if I bored you guys.. Good night..