Recovering from initial losses, the Sensex at the Bombay Stock Exchange gained 51 points, or 0.3 per cent, to close at 19,743, on fag-end buying by investors, today. The Nifty at the National Stock Exchange rose 13 points, or 0.2 percent, to 6,002.But stock markets in Japan, China, Hong Kong, South Korea and Singapore declined between 0.4 percent and 0.9 percent.