The Sensex at the Bombay Stock Exchange surged 138 points, or 0.7 percent, to 20,424 in early trade, today, on sustained buying by funds and retail investors, amid firm regional bourses. Later, the Sensex trimmed its initial gains, to stand 85 points, or 0.4 percent in the green, at 20,371 in afternoon trade, a short while ago. The Sensex had gained nearly 600 points in the previous four trading sessions. Stock indices in Japan, China, Hong Kong, Indonesia, Singapore and Taiwan had gained between 0.1 percent and 1.5 percent, today, boosted by US equities hitting record closing highs on Friday