Extending its losses for the eight straight session, the Sensex at the Bombay Stock Exchange tumbled 425 points, or 2.6 percent, to close below the psychological 16,000 mark, at 15,946 on Monday.The market fell on heavy foreign fund outflows amid a depreciating rupee, and falling global markets. The Sensex has now lost more than 1,600 points in just eight trading sessions. The Nifty at the National Stock Exchange slumped 127 points, or 2.6 percent, to 4,778.The bourses in Japan , China , Hong Kong , South Korea and Singapore fell between 0.1 percent and 1.4 percent. But the European markets took a much bigger hammering, on euro-zone debt worries.