Mukesh Ambani-led RIL commanded a market value of Rs 2,46,883 crore (Rs 2,468.83 billion) at close of market hours on Monday, higher than ONGC's Rs 2,35,233 crore (Rs 2,352.33 billion).
RIL shares attracted good buying support in a bullish market and closed up by 4.80 per cent at Rs 754.05 a piece on the Bombay Stock Exchange.
The stock lends maximum weight to the benchmark Sensex Sensex that rose 3.58 per cent -- the most in nearly six-months -- to close at 16,416.33.
ONGC's share prices, however, declined 1.10 per cent to Rs 274.95 a piece.
On Friday, ONGC had toppled RIL to claim the title of the country's most-valued company.
At the end of Friday's trade, RIL had a market cap of Rs 2,35,571 crore (Rs 2,355.71 billion) , while ONGC commanded a market value of Rs 2,37,842 crore (Rs 2,378.42 billion).
RIL had first toppled ONGC to become the country's most-valued firm in late 2006.
In the past few days, a game of musical chairs was being played out on bourses between RIL, CIL and ONGC for the title of country's most-valued
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