The Dow Jones and S&P 500 indexes closed 1.56% and 1.2% down, after tumbling more than 3% earlier. The main European stock exchanges also slid to a 15-month low. Analysts say investors fear low oil prices reflect a fall in demand for fuel which could be a sign that growth in the global economy is slowing down. The falls in Europe and the US came after Asian stocks closed sharply lower. Markets in Dubai closed at a 28-month low, while in Japan shares fell to their lowest level since October 2014. Many markets are now in so-called bear market territory – a fall of 20% or more from their most recent peak.