Goldman Sachs has quietly overtaken Chevron and ExxonMobil to become one of the biggest natural gas merchants in North America, expanding in physical commodities trading even as other banks pull back. The Wall Street institution last year bought and sold 1.2tn cubic feet of physical gas in the US — equal to a quarter of the country’s residential consumption and more than twice its volumes in 2013, a recent regulatory filing revealed. Goldman is now the seventh-largest gas marketer in North America, according to Natural Gas Intelligence. The gas utility serving households in Buffalo, New York last year purchased 11 per cent of its supply from Goldman, a securities filing showed. Power plants that produce electricity for copper mines in northern Mexico also buy gas from the bank, according to government reports and industry executives. Goldman’s commodities division, known as J Aron, is listed as a shipper on huge pipelines including the Texas Eastern, which last month ruptured into a fireball that critically injured a man. Goldman has grown the business even as banks await fresh rules on handling physical commodities such as oil, gas and aluminium. The Federal Reserve has said lethal gas explosions illustrate the risks banks face.