Markets decline for the third straight session; Sensex ends at 6-month low: Benchmark indices have closed lower with the Sensex ending at 6-month low on persistent selling by foreign institutional investors as concerns regarding MAT continue to float around. Weakening of rupee along with rebound in crude oil prices has dampened the sentiments.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 under-performed the benchmark indices as BSE Mid-cap and Small-cap indices were down nearly 2%. The rupee fell to its lowest in 20 months on Thursday, weighed down by concerns over the government's taxation policies that threaten to reduce the allure of local assets for foreign institutions, while a global debt sell-off also hurt.