Mumbai: State-run ONGC on Friday toppled billionaire Mukesh Ambani-led Reliance Industries as the country's most valued company, as a regular game of musical chairs for the top slot continued in the stock market.

With a market valuation of Rs 2,37,842 crore, slightly higher than RIL's Rs 2,35,571 crore, the PSU energy major reclaimed the top position from the private sector corporate giant after a gap of nearly four and half years.

However, ONGC's lead over RIL is barely about 1 per cent (about Rs 2,200 crore) and their performances would be keenly watched when stock market resumes trading next week.

RIL had first toppled ONGC to become the country's most-valued firm way back in late 2006, but the state-run energy giant later reclaimed the top position, albeit only for a few brief period. RIL has managed to stay on the top since February 2007, except for past few days.

A situation similar to game of musical chairs is evident in the stock market for past few days when there have been many twists and turns in the top positions of the country's most valued firms.

Earlier on August 17, state-run Coal India Ltd (CIL) dethroned RIL as the top-valued firm, ending the private sector energy's giant over four-year reign at the top.

Two days later on August 19, RIL briefly slipped to the third position after CIL and ONGC but returned to the second slot at the time of the market closing.

However, CIL's top position proved to be short-lived as RIL reclaimed this position within six days on August 23.

A day later on August 24, CIL lost further ground and slipped to the third position after RIL and ONGC.