Closing price of CESC on 21st Jan 2021 is 70.85.
Open Price on 22nd Jan 2021 is 66.5
Dividend ex date 22nd Jan 2021 = 45 rs (source)
So open price with divedend is 45+66.5 = 111.7
Total gap up = 111.7-70.85)/70.85*100=57.65%
How did this happen? Is data wrong? Which one? Price data? Dividend data? Or the data got adjusted for dividend? If yes, why? Dividend data don’t get adjusted in price like splits, right?