The Sensex at the Bombay Stock Exchange plunged 223 points, or 1.2 percent, to slip below the 18,000-mark, at 17,887, in opening trade, this morning, on continued selling by investors, amid a sustained fall in the global markets. Later, the Sensex recovered somewhat, but still stood 161 points, or 0.9 percent in negative territory, at 17,949, in afternoon deals, a short while ago. Global markets also dropped, with the bourses in Japan, South Korea, Indonesia, Singapore and Hong Kong down by a hefty 1.4 percent to 2.5 percent, today, on mounting concerns about slowing global economic growth, and shaky sovereign debt. Across in the US, the Dow Jones Industrial Average had slumped 2.2 per cent, overnight.