The BSE Sensex is falling today mainly due to the impact of newly imposed 50% US tariffs on Indian goods, which started recently. This tariff increase has created uncertainty among exporters and dampened investor sentiment. Additionally, continued foreign institutional investor selling, weak global market cues including Asian and US market falls, and concerns around US monetary policy under Trump's influence are contributing to the decline. The market also faces pressure from high valuations, with Indian stocks trading at levels considered expensive compared to earnings growth. These combined factors are causing the BSE Sensex's downward movement today, with notable losses in heavyweight stocks and sectors like IT and banking.