Conversion of non-listed shares in to listed ones

I had shares of an un-listed company " A" purchased ten years back in 2012. Now this company has got merged with an already listed company " B" of the same group with due approval from NCLT. Pursuant to this Composit Scheme of Amalgamation and Arrangement, I have been allocated shares of company B in lieu of my holding in company A. Is this a taxable event from income tax point of view? If yes, how the tax liability shall be calculated?