India's BSE Sensex gave up early gains to close about 0.3% down at 80,158 on Tuesday, reversing Monday's advance, on profit booking amid caution ahead of the GST Council meeting and global uncertainties. Investors are eyeing the two-day 56th GST Council meeting beginning September 3, where major reforms for select sectors are expected, including a proposed 10-percentage-point cut in consumption tax on around 175 products, such as shampoos, hybrid cars, and consumer electronics. At the same time, the NSE's weekly F&O derivatives expiries shifted to Tuesday from Thursday starting today, marking a major shift in trading dynamics and adding extra pressure and volatility. Meanwhile, US President Donald Trump called the India–US trade deal a 'one-sided disaster' on Truth Social, adding that while India offered zero tariffs on US imports, the window for an agreement may have closed. On equities, M&M, ICICI Bank, Kotak Bank and Asian Paints were among the major laggards.