The Indian rupee’s top two forecasters are at odds as to how vulnerable the world’s fastest-growing major economy is to outside shocks. HDFC Bank Ltd., which had the most accurate estimates in Bloomberg’s quarterly rankings, sees US Federal Reserve policy tightening driving a 2.5 per cent decline in the currency to 68.50 per dollar by March 31, from 66.81 on Monday. National Australia Bank Ltd., placed second, says the rupee will strengthen to 66.20 as economic growth and a narrowing current account deficit help offset any outflows from emerging markets.“The rupee could take a bit of beating along with other regional currencies,” said Tushar Arora, HDFC’s senior economist for treasury based near New Delhi. The Fed’s December decision “could lead to uncertainty in global financial markets and a risk-off episode,” he said.HDFC’s view the rupee will weaken toward its record low of 68.845 set in August 2013 was bolstered Thursday, when the currency slid the most in three months after Fed minutes boosted the case for higher US rates. India’s currency strengthened 1.4 per cent in the third quarter, the most in two and a half years, and National Australia Bank says foreign investors will keep buying.“India is experiencing relatively strong growth, which should attract inflows,” said Julian Wee, senior markets specialist for Asia at the lender in Singapore. “Gradual lowering of the policy rate should also benefit both local equities and bonds, while leaving a still-healthy carry premium over the dollar and many other Asian currencies.”India’s economy may expand 7.7 per cent this year, up from 7.6 per cent in the previous 12 months, according to the weighted average forecast in a Bloomberg survey of analysts. Ten-year bonds yield 6.77 per cent, the second-highest among major Asian markets after Indonesia, a further attraction for overseas investors.Signs of imminent US tightening have seen the currency decline 0.4 per cent so far in October after three successive months of gains. Global funds cut their holdings of rupee debt by 64.7 billion rupees ($968 million) this month through Friday.The rupee is also under pressure as an estimated $26 billion in deposits made by non-resident Indians in 2013 started to mature in September. The RBI predicts that $20 billion of this will leave the country by year-end.“While we expect the situation to remain largely managed, there could be short-term liquidity mismatches, which could lead to some volatility in the exchange rate,” HDFC’s Arora said.The rupee has strengthened about 3 per cent from a recent low of 68.7875 set in February as the current-account deficit has narrowed and inflation has slowed, boosting confidence in Asia’s third-largest economy. Prime Minister Narendra Modi was able get parliamentary approval for a national sales tax in August, a move that should bolster government revenue going forward.“The RBI will probably be quite keen to keep the rupee somewhat stable against the dollar, which should be fairly manageable given the strong growth rate and the attractive carry,” National Australia Bank’s Wee said. “We continue to see mild and broad upside in the dollar, but the rupee should outperform within the region.”