S. 43(5) : Speculative transaction – Derivatives – Losses – Set off from one source against income from other source under same head of income- Loss incurred on account of derivatives would be deemed business loss under proviso to S. 43(5) and not speculation loss, Explanation to S. 73 would not be applicable- Interpretation- Two non jurisdictional High Court taking different view-View favourable to the assessee is followed . [ S.70, 73(4) ]