Erasing almost all its initial gains on fag-end selling, the Sensex at the Bombay Stock Exchange failed to hold the 20,000-level, and closed with a marginal gain of 14 points, or 0.1 percent, at 19,981, today, on profit-booking, amid a subdued global trend. The Nifty at the National Stock Exchange declined 1 point, to 5,992. Stock markets in Japan, China, Hong Kong, South Korea and Singapore ended mixed.