Equity benchmark indices Sensex and Nifty tumbled over 2 per cent on Friday as investors resorted to profit-booking following a two-day rally, amid weak global cues.Ongoing tensions between the US and Iran continued to weigh on market sentiment, fuelling concerns over any near-term de-escalation.The downturn was further aggravated by rising crude oil prices, a weakening rupee against the US dollar, and sustained foreign fund outflows.The 30-share BSE Sensex tumbled 1,690 points to close at 73,583, while the ...