The BSE benchmark Sensex was trading 10 points or 0.07 per cent down at 15,847 points in afternoon deals. The 30-share Sensex fell by 151 points in opening trade today as participants booked gains recorded in the previous session amid a weakening trend on other Asian bourses.The wide-based National Stock Exchange Nifty was also trading 2 points or 0.04 percent down at 4,754 points.Asian market lower today, as lingering concerns over Europe's debt crisis kept investors sidelined. So, Japan's Nikkei shed 0.1%; Hong Kong's Hang Seng lost 1.4%; Singapore's Strait Times index slid 1.2%; China's Shanghai Composite index slipped 0.7% and South Korea's Kospi fell 0.9%.European markets fell amid initial volatility as investors continued to fret over euro-zone troubles and Hungary suffered a downgrade. London's FTSE-100, France's CAC-40 and Germany's DAX slipped 0.3% and 0.6% in intra-day trade, today.Meanwhile, Moody's Investors Service cut Hungary's government bond rating one notch to Ba1 late evening yesterday.The ratings firm retained a negative outlook on Hungarian bonds, saying it's looking increasingly uncertain the country will meet its fiscal consolidation and debt reduction targets.