Mumbai, Aug 19 (PTI) Benchmark stock indices Sensex and Nifty advanced on Tuesday, marking their fourth consecutive day of gains, mainly driven by Reliance Industries and Tata Motors.

Rising for the fourth trading day in a row, the 30-share BSE Sensex edged higher by 370.64 points or 0.46 per cent to settle at 81,644.39. During the day, it jumped 482.13 points or 0.59 per cent to 81,755.88.

The 50-share NSE Nifty climbed 103.70 points or 0.42 per cent to 24,980.65.

Optimism prevailed in the market, buoyed by plans for big bang reforms in the GST regime by Diwali and easing geopolitical worries, analysts said.

Among Sensex firms, Tata Motors rose the most by 3.5 per cent while Adani Ports gained 3.16 per cent. Reliance Industries rose by 2.82 per cent. Eternal, Tech Mahindra, Kotak Mahindra Bank, Hindustan Unilever and Maruti were also among the gainers.

However, Bajaj Finserv, Power Grid, Mahindra & Mahindra and HCL Tech were among the laggards.

"The national market continued the renewed momentum, buoyed by expectations of GST rationalisation and a recent upgrade in India's credit rating. Additional optimism came from signs of easing geopolitical tensions between Russia and Ukraine, shifting the near-term outlook from consolidation to a more constructive stance," Vinod Nair, Head of Research, Geojit Investments, said.

In Asian markets, South Korea's Kospi, Japan's Nikkei 225 index, Shanghai's SSE Composite and Hong Kong's Hang Seng settled lower.

Markets in Europe were trading higher. The US markets ended on a flat note on Monday.

Global oil benchmark Brent crude declined 0.93 per cent to USD 65.98 a barrel.

Foreign Institutional Investors (FIIs) bought equities worth Rs 550.85 crore on Monday, according to exchange data.

On Monday, the Sensex jumped 676.09 points or 0.84 per cent to settle at 81,273.75. The Nifty climbed 245.65 points or 1 per cent to end at 24,876.95. PTI SUM SUM MR

GST reform expectations spur market rally as tax-policy rationalisation shifts investor sentiment and attracts portfolio inflows. Plans for comprehensive GST reform by Diwali drove investor optimism and served as the primary catalyst for equity gains, supported by a sovereign credit rating upgrade and easing geopolitical tensions; these regulatory signals shifted market sentiment toward constructive risk-taking, concentrated in large-cap sectors, and were reinforced by net foreign portfolio inflows within a mixed global market backdrop.