The Sensex at the Bombay Stock Exchange gained 72 points, or 0.4 percent, to 16,877, on selective buying by investors, amid rising Asian and European markets, today. During the session, the Sensex had crossed the 17,000 mark. The Nifty at the National Stock Exchange rose 23 points, or 0.5 percent, to 5,063. Stock markets in Japan, China, Hong Kong, South Korea and Singapore rose between 0.3 percent and 1.7 percent, on hopes that the euro-zone debt crisis may ease.