According to media reports, the government examined bids in nine coal blocks, off which five got approved and four were cancelled.
The Coal Ministry rejected the bids of Jindal Steel and Balco amid reports of speculation of cartelisation during the recent coal block auction.
Reports added that the government will take a final decision on these mines after deliberations.
The stock is now down 11 per cent at Rs 146. Around 351,000 shares have changed hands at the opening bell on the BSE.
Meanwhile, the Sensex has gained 109 points at 28,371.