Income from Derivative will be treated as normal business income subject to section 43(5) of Income tax act , that means you can take the benefit of all the expenses which you incurred under this category (related to derivative). Considering this is considered as normal business income that's why normal tax rate slab will be applied based on your classification in Income tax.
Please note that as per latest ruling given by honorable Delhi high court in CIT v DLF commercial developers ltd(2013) , iterates that explanation provided in section 43(5) regarding classification of derivative income into normal business income does not applicable for section 73 (set off and carried forward losses) of income tax act i.e. Loss on derivative income can not be offsetted by other normal business income.
Rgds,
Madav