ONGC on Thursday reclaimed the spot as the country's most-valued company, pushing IT giant TCS to the second slot.
At the end of trade, ONGC commanded a market value of Rs 2,89,047 crore (Rs 2,890.47 billion).
This is about Rs 4,428 crore (Rs 44.28 billion) more than TCS's m-cap of Rs 2,84,619 crore (Rs 2,846.19 billion).
ONGC scrip ended 0.82 per cent higher, while TCS lost 1.02 per cent on the BSE.
Reliance Industries with a market capitalisation of Rs 2,71,904 crore (Rs 2,719.04 billion) was at third place, followed by ITC (Rs 2,66,133 crore or Rs 2,661.33 billion) and Coal India (Rs 1,88,543 crore or Rs 1,885.43 billion).
Market capitalisation or the value of a listed company is arrived at by multiplying the total number of its shares with its stock price on a particular day or time.
This figure changes daily with the change in the stock price.
The BSE 30-stock index, Sensex, advanced by 34.37 points, or 0.17 per cent to 20,247.33, the level last seen in January, 2011.
The index had gained 521 points in last two trading sessions.