Iron ore miner National Mineral Development Corporation , NMDC's offer for selling 39.65 crore shares was over-subscribed on Wednesday, following hectic trading towards the end of the day, ensuring at least Rs 5,900 crore for the exchequer.Against the offer for sale of 39,64,71,600 shares, or 10 per cent, of government's stake in the company, the offer has received 45,67,70,509 bids at an indicative price of Rs 149.11 per share till 3:35 pm , according to data available with Bourses.The government had set the floor price for the offer at Rs 147 a piece. NMDC's shares today settled at Rs 154.25, 3.17 per cent down over the previous closing.NMDC has kept one-fourth of the issue reserved for mutual funds and insurance companies. However, no single bidder, other than mutual funds and insurance firms, would be allocated more than 25 per cent of the total offer, the iron ore miner had said in an exchange notification earlier.NMDC is the second disinvestment candidate in the current fiscal, in which the government plans to raise Rs 30,000 crore by selling stakes in around a dozen PSUs.