The Sensex at the Bombay Stock Exchange rebounded from the lows of the day, but still ended with a loss of 223 points, or 1.3 percent, at 16,632, today. Earlier in the session the Sensex had plummeted a massive 644 points, as concerns about Dubai's debt problems rattled markets around the world. The Nifty at the National Stock Exchange fell 64 points, or 1.3 percent, to 4,942.Other Asian stock markets took a much bigger hammering, with key indices in Japan, China, Hong Kong and South Korea slumping between 2.5 percent and 5 percent.