Remaining weak in afternoon trade, the Sensex at the Bombay Stock Exchange stood 84 points, or 0.4 percent in negative territory, at 21,050 a short while ago.Earlier in the morning, the Sensex had declined 24 points, or 0.1 per cent, to 21,110, as funds and retail investors booked profits, amid weak regional bourses.The 30-share Sensex had gained 418 points in the previous two trading sessions.Stock markets in Japan, Hong Kong, Singapore, South Korea and Taiwan had lost between 0.2 percent and 3 percent on Tuesday.The US Dow Jones Industrial Average had ended 1.1 per cent lower in Monday's trade.