Snapping a three-day fall, the Sensex at the Bombay Stock Exchange on Friday gained 91 points to regain the 20 K mark to close at 20,032, on buying in blue-chips. The Nifty at the National Stock Exchange rose 30 points to 6,018.But stock markets in Japan, China, Hong Kong, and South Korea lost between 0.5 percent and 1.8 percent. The Midcap and the Smallcap indices, however recorded huge losses. The Midcap index closed 8,302 with a loss of 73 points. The Smallcap index closed at 10,597 with a loss of 160 points.