Giving up all of its initial gains, the Sensex at the Bombay Stock Exchange stood 6 points in negative territory, at 18,444, amid volatility, in afternoon trade, a short while ago. Earlier in the morning, however, the Sensex had opened with a gain of 43 points, or 0.2 per cent, at 18,494, on selective buying by funds at existing lower levels. The Sensex had lost over 590 points in the last three trading sessions.Key stock indices in China, Indonesia, Singapore, South Korea and Taiwan had declined between 0.1 percent and 2.2 percent, today.