The Sensex today dropped by 159 points on heavy selling by funds influenced by weakness across the globe over continued concerns that the Eurozone debt crisis might hit economic recovery. Sensex, which fell nearly 271 points in the previous session, fell further by 159 points to 16,836, after touching the day's low of 16,551 points. The National Stock Exchange index Nifty lost 34 points to 5,060 points after touching a low of 4,966 points. The selling pressure gathered momentum as Asian stock markets tumbled on selling by funds on concerns that global economic recovery might become a casualty to European nations' efforts to reduce fiscal deficit.