New Delhi, Oct 10 : The BSE Sensex crossed the 66,000 mark during trade on Tuesday with a gain of 559 points. Sensex is trading at 66,072 points on all round buying in heavyweight stocks. Bharti Airtel is top gainer, up more than 2 per cent followed by Kotak Mahindra Bank and Tata Motors. ICICI Bank, Axis Bank, Maruti, SBI, Bajaj Finserv, Infosys, M&M, JSW Steel are all up more than 1 per cent in trade. Meanwhile, the uncertainty associated with the Israel-Hamas conflict continues, says V.K. Vijayakumar, Chief Investment Strategist at Geojit Financial Services. "It can take a turn for the worse if Israel starts ground operations in Gaza. The possibility of easing of tensions also cannot be ruled out since Hamas will bargain with the captured Israeli hostages. Unlike economic and market trends, geopolitical developments cannot be predicted. This uncertainty will weigh on markets," he said. On the economic front there are some positive developments. The decline in the dollar index to 105.95 and the US 10-year bond yield falling to 4.65 from the recent high of 4.88 are positive developments for equity markets, he added. Even though FIIs continue to sell in India, the intensity of selling is coming down. More importantly. DIIs are increasing their purchases. Calibrated buying in small quantities in quality stocks in banking, automobiles, IT, capital goods and real estate/construction would be a good strategy for long-term investors, he added. /IANS