Mumbai: Sensex and nifty both indices had a weak closing, with the BSE index ending at 6-month lows, due to persistent selling by foreign institutional investors on MAT concerns. Weakening of the rupee and rebound in crude oil prices further dampened sentiments.According to analysts, high-speed trading that takes place through dynamic software programs has worsened the fall; the markets were already on the edge following the emergence of a broad selling pressure as FIIs unwound positions on MAT worries and domestic traders remained hesitant to step in due to weak corporate earnings in Q4. The 30-share Sensex ended down 118.26 points at 26,599.11 mark, the lowest level since Oct 21, 2014. The 50-share Nifty was down 39.70 points at 8,057.30 after breaching 8,000 mark in intra-day trade. The broader markets underperformed the benchmark indices- BSE Midcap and Smallcap indices were down nearly 2%.