The government has fixed 40 rupees a share as the floor price for up to 10 percent stake sale in aluminium major National Aluminium Co. Ltd (Nalco), giving a discount of nearly 10 percent. The sale is expected to fetch a minimum of 1,031 crore rupees. The offer for sale is scheduled to be held today through a special window on BSE and NSE.The decision on base price was taken on Wedenesday by an Empowered Group of Ministers, headed by Finance Minister P. Chidambaram.