Let's understand this with an example. Suppose you bought 30 shares of HDFC Ltd on 1 April 2019 at ₹ 2,000 per share, thus spending ₹ 60,000. As per the share exchange ratio upon merger, you are entitled to receive 50.4 (42/25*30) shares of HDFC Bank. But since there is no concept of fractional shares in India, you will be issued 50 shares of HDFC Bank. Further, as per the Bank's BSE announcement of 14 July, the share allotment exercise has been done and the listing of these shares is under process.