"ONGC Board approved the red herring prospectus on Monday, which will be filed as per the instructions of the government," ONGC chairman and managing director A K Haziraka told reporters in New Delhi.
The red herring prospectus is likely to be filed with market regulator Securities and Exchange Board of India on September 5.
The follow-on public offer, through which the government is selling 5 per cent of its stake in ONGC, may open on September 20 or 27.
"Keeping the strong fundamentals of ONGC in view, we are confident that the response from the investors will be overwhelming," he said.
On August 29, ONGC's board approved the RHP after incorporating the company's financial results for the April-June quarter.
The government plans to sell 5 per cent, or 427.77 million shares, through the FPO.
"We are prepared for the FPO and we are awaiting a signal from the department of disinvestment, as this is the government's share sale," the official said.
The FPO was originally planned in the 2010-11 fiscal, but was later deferred to April 5 as the company did not have an adequate number of independent directors on its
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