The Sensex at the Bombay Stock Exchange lost 164 points, or 1 percent, to close at 16,617, today. The Nifty at the National Stock Exchange shed 47 points, or 0.9 percent, to close below the 5,000 level, at 4,987. The domestic markets fell, after credit ratings agency, Fitch warned that the United Kingdom faces a formidable fiscal challenge, adding to concerns that the European Union's debt crisis is spreading. But stock markets in Japan, China, Hong Kong, and South Korea rose between 0.1 percent and 0.8 percent.