The Sensex at the Bombay Stock Exchange declined 106 points, or 0.6 per cent, to 17,151, in opening trade, this morning, on profit-booking by funds and retail investors, amid weakness in the other regional bourses. Later, the Sensex trimmed its losses, and stood 75 points, or 0.4 per cent in the negative zone, at 17,183 in afternoon deals, a short while ago.Key stock indices in Japan, China, Hong Kong, Indonesia, Singapore and South Korea were down by between 0.2 percent and 2 percent, today, as investors waited for more clues on the state of the US economy. The US Dow Jones Industrial Average had lost 0.3 per cent, overnight.