The Sensex at the Bombay Stock Exchange fell a modest 24 points, to 16,123 in opening trade, this morning, on continued selling by investors, amid interest rate concerns, and subdued Asian markets. Afterwards, the Sensex briefly rebounded into positive territory, before again slipping into the negative zone, and had fallen 123 points, or 0.8 percent, to 16,023 in volatile trade, a short while ago. The 30-share Sensex has already lost more than 350 points in the past two trading sessions.Other regional bourses in Japan, China, Singapore, Hong Kong, South Korea and Taiwan were trading mixed, on investor caution ahead of a US central bank meeting, today. Over on Wall Street, the Dow Jones Industrial Average had lost 1.5 per cent, overnight.