New Delhi: The government’s 1.5 per cent stake sale in ONGC had a smooth start on Wednesday, with institutional buyers putting in bids worth Rs 4,854 crore and over-subscribing the portion reserved for them. The government is selling up to 1.5 per cent of its stake in the country’s top oil and gas producer ONGC at a floor price of Rs 159 a share to raise about Rs 3,000 crore through an offer for sale (OFS).