State-run Coal India today toppled billionaire Mukesh Ambani-led Reliance Industries as the country's most valued company, with a slightly higher market valuation around mid-day.

At around 1200 hours on the National Stock Exchange, Coal India Ltd (CIL) commanded a market cap of Rs 250,759.67 crore, with an over 2 per cent rise in its share price. At that time, RIL had a market cap of Rs 250,580.21 crore on the NSE.

A few minutes later, CIL's market valuation exceeded that of RIL on the BSE as well. At around 1206 hrs, RIL's market cap on the BSE stood at Rs 2,50,468 crore, slightly lower than CIL's Rs 2,50,538 crore.

At 1206 hours today, RIL shares were trading 0.82 per cent higher at Rs 765.20, while CIL was up 2.32 per cent at Rs 396.60.

CIL has been closing the gap on RIL in terms of market valuation over the past few days and on August 9, the gap slipped below 1 per cent.

RIL extended its lead by some margin since then, but the PSU coal giant managed to surpass the private sector energy giant's market capitalisation in today's trade at around 1200 hours.

At yesterday's close, RIL had a market cap of Rs 248,504.44 crore, as against CIL's 244,822.28 crore, on the BSE.

At the time of today's market opening also, RIL had a higher market cap of Rs 249,454 crore than CIL's Rs 244,822 crore.

Way back in 2006, RIL had toppled ONGC to emerge as the country's most valued firm and has managed to stay on the top since then.

ONGC had also come very close to toppling RIL as the country's most valued firm last week, but lost ground in the past few trading sessions. The stock was trading 2.4 per cent higher at Rs 279.50, with a market cap of Rs 2,39,125 crore, in today's trade at 1220 hours.

Marketmen would be keenly watching the three stocks to see whether RIL is able to regain its lead or loses further ground in the market-cap charts.

RIL's stock has been under acute pressure in recent past, while ONGC and CIL have managed to outperform in a weak market on several occasions in the past few days.