The Sensex at the Bombay Stock Exchange declined 86 points, or 0.5 per cent, to 18,608 in early trade, today, as funds and retail investors booked profits ahead of tomorrow's expiry in the derivatives segment, amid subdued Asian bourses. Later, the Sensex remained weak, and stood 87 points, or 0.5 per cent in the red, at 18,607 , in afternoon deals, a short while ago.Stocks markets in Japan, China, Hong Kong Indonesia, Singapore, South Korea and Taiwan had dropped between 0.6 percent and 1.9 percent, today. The US Dow Jones Industrial Average had ended 0.8 per cent lower in yesterday's trade.