The Sensex at the Bombay Stock Exchange plunged 221 points, or 1.4 per cent, to again slip below the 16,000 mark, at 15,845, in early trade, this morning.The market fell on across-the-board selling by investors, as weak global markets, and global growth jitters weighed on investor sentiment.Later, selling pressure intensified, and at one stage the Sensex had lost a massive 587 points.Thereafter, the Sensex trimmed its losses only very slightly, and still stood a hefty 440 points, or 2.7 percent in negative territory, at 15,625 in afternoon deals, a short while ago.Other regional markets in China, Singapore, Hong Kong, Indonesia, South Korea, and Taiwan were down by between 0.6 percent and 2.8 percent, today, after a disappointing manufacturing survey from China, and a weaker-than-expected estimate of US economic growth. Over in the US, the Dow Jones Industrial Average had shed 0.5 per cent, overnight.