Shares of state-run Nalco today tumbled nearly six per cent in early trade, ahead of its share sale programme where the government will sell up to 10 per cent stake in the aluminium major.

After making a weak opening, shares of the company further lost 5.61 per cent to Rs 43.7 on the BSE in an overall weak stock market.

Nalco had yesterday said the government would offload more than 12.89 crore shares, amounting to about five per cent stake in the company.

There would also be an "option to sell an additional 12,88,61,925 equity shares of the face value of Rs 5 each of the company... Collectively aggregating to approximately 10 per cent of the total paid up equity share capital of the company," the company had said in a filing to the BSE.

The sale, which is scheduled for tomorrow may fetch the exchequer around Rs 1,100 crore.

The government currently holds 87.15 per cent stake in Nalco.

Meanwhile in the broader market, the BSE benchmark Sensex was trading at 19,280.96, down 81.59 points at 1040 hrs.