The S&P BSE Sensex and NSE Nifty 50 indexes on Monday staged their biggest single-day gain since May 20, after the government announced measures to boost the slowing economic growth. In a presentation after market hours last Friday, Finance Minister Nirmala Sitharaman announced the government's decision to roll back higher taxes on domestic and foreign portfolio investors imposed as part of the Finance Bill 2019 last month. The Sensex surged 793 points or 2.16 per cent to close at 37,494 and the NSE Nifty 50 index jumped 228 points or 2.11 per cent to settle at 11,058.