The Sensex at the Bombay Stock Exchange plunged 291 points, or 1.6 percent, to end at an over 4-month low of 18,308, today. The Sensex fell on continued selling by investors, as the rupee slipped to a record low against the dollar, and amid concerns about the US rolling back its monetary stimulus. The Nifty at the National Stock Exchange declined 93 points, or 1.7 percent, to 5,415.Stock markets in Japan, China, Hong Kong, South Korea and Singapore ended mixed.