Govt-owned ONGC announced that it will acquire the government's entire 51.11 per cent stake in HPCL for Rs 36,915 crore.
ONGC will pay the government Rs 473.97 per share, a premium of over 10 per cent of the 60-days weighted average of HPCL's scrip.
In a stock exchange filing, ONGC said "shares will be acquired against cash" and the transaction will be closed before month-end.
ONGC's share had closed at Rs 193.60 on BSE on Friday, down 0.23 per cent over its previous close.
HPCL shares traded last at Rs 416.55, up 1.34 per cent.