Posting its fourth straight day of losses, the Sensex at the Bombay Stock Exchange declined 182 points, or 0.9 percent, to 19,137, after volatile trade, on Friday, with investors rattled by the housing finance scam, and amid weak global markets. The Nifty at the National Stock Exchange shed 48 points, or 0.8 percent, to 5,752.Stock markets in Japan, China, Hong Kong, and South Korea lost between 0.5 percent and 1.3 percent.