The rupee extended its losses and touched an all-time low of 77.42 against the US dollar in early trade on Monday weighed down by the strength of the American currency in the overseas market and unabated foreign fund outflows.At the interbank foreign exchange, the rupee opened at 77.17 against the American dollar, then lost ground to quote at 77.42, registering a fall of 52 paise from the last close.On Friday, the rupee had slumped 55 paise to close at 76.90 against the US dollar. The Indian rupee opened weaker on Monday against the dollar as weakness in global equities on concerns over the economic outlook and rising bond yields weighed on sentiments, said Sriram Iyer, Senior Research Analyst at Reliance Securities.Forex traders said that risk appetite has weakened amid mounting concerns about inflation that may trigger more aggressive rate hikes by the global central banks. The dollar index, which gauges the greenback's strength against a basket of six currencies, was trading 0.35 percent higher at 104.02, tracking rising US yields and fears about higher interest rates. Moreover, Asian and emerging market peers started weak this Monday morning and will weigh on sentiments.On the domestic equity market front, the 30-share Sensex was trading 737 points or 1.34 percent lower at 54,098.58 points, while the broader NSE Nifty declined 220.25 points or 1.34 percent to 16,191.00 points. Global oil benchmark Brent crude futures rose 0.14 percent to USD 112.55 per barrel.Foreign institutional investors were net sellers in the capital market on Friday, as they offloaded shares worth Rs 5,517.08 crore, as per stock exchange data.