Mumbai: The Bombay Stock Exchange benchmark Sensex tumbled by over 359 points at mid-session today on heavy selling by funds over concerns that Europe's debt crisis might slow global economic growth. The Sensex, which had opened lower, fell by 359.62 points to 16,109.93 at 1230 hrs as stocks in the metal, capital goods, consumer durables and auto sectors suffer losses. The gauge has dropped 10 per cent from its April 7 peak. The broad-based National Stock Exchange index Nifty lost 111.15 points to 4,832.80 at the same time. Trading sentiment remained bearish on all-round selling after Asian stock markets fell and European stock markets opened on a weak note over the eurozone crisis. Besides metals, stocks in software exporting companies declined. Wipro fell 1.9 per cent to Rs 635.70, the lowest in more than eight months. Tata Consultancy Services, the largest software services exporter, slid 1.