The Sensex at the Bombay Stock Exchange surged 412 points, or 2.2 percent, to close at an over 3-week high of 18,980, today, after the new Reserve Bank governor announced a slew of measures to boost the currency and the economy. The Nifty at the National Stock Exchange jumped 145 points, or 2.7 percent, to 5,593.Stock markets in Japan, Hong Kong, South Korea and Singapore gained between 0.1 percent and 1.2 percent.