Regular Trading Session (India Standard Time): 9:15 - 15:30. The CNX Nifty, a free-float market-capitalization index, is the leading index for large companies on the National Stock Exchange of India. It consists of 50 companies representing 24 sectors of the economy. The base level is defined as 1000 on November 3, 1995. In January 2005, its level was almost 2000.