Comment on Notice under Section 139(9)? - Possible reason
For all speculative transactions, aggregate or absolute sum of both positive and negative differences from trades is to be considered as a turnover. So if you buy 100 share of Reliance at 800 in the morning and sell at 820 by afternoon, you make a profit or positive difference of Rs 2000, this Rs.2000 can be considered as turnover for this trade.