The BSE Sensex closed about 0.7% firmer at 80,364.5 on Monday, after three consecutive sessions of decreases. Upbeat domestic economic data and hopes for GST rationalisation at the upcoming council meeting supported market sentiment, even as global challenges persist. India's economy grew by a stronger-than-expected 7.8% in April-June, its fastest pace in five quarters, after a 7.4% rise in the prior period. A separate report showed HSBC India Manufacturing PMI rose to 59.3 in August, up from 59.1 in July, reflecting sustained strength in the sector. On the corporate front, M&M (+3.5%), Tata Motors (+3.2%) and Trent (+2.6%) were the top gainers while Sun Pharma (-1.9%), ITC (-1%) and Hindustan Unilever (-0.6%) were among the major laggards.