On 13th March 2016, when we recommended a 'Buy' on Crompton Greaves it was trading in 140's and on 15th March, it went ex-demerger in 40's. Since the book value of de-merged consumer business was nil, we can apportion entire cost to Crompton Greaves and 'Nil' to Crompton Greaves Consumer Entity.

This implies we made a notional capital loss of ~Rs100 on each share of Crompton Greaves which can be set-off against any short term capital gains (STCG) for FY16.
If you have any such net STCG attracting 15% taxation, you may sell Crompton Greaves at current price and book this notional loss, remember to do this exercise before 31st March. You may buy it back the next day (buying back same day would be counted as intra-day trade and would not book losses).

This also means that the implied purchase price of CGCEL will be Zero and if anyone sells it within 12 months, it will attract STCG Tax on entire proceeds nullifying this benefit. Further, the implied date of acquisition of CGCEL shares, for the purpose of computation of capital gain/loss (Short-Term/Long-Term) will be the date of acquisition of original CG shares. However, at this point in time that should not worry us as we intend to hold CGCEL for long term.

Refer http://www.bseindia.com/corporates/anndet_new.aspx?newsid=a8f93a92-e98e-4c79-a501-da568f1b0698