The U.S. is the world's largest producer of oil and natural gas. It is one of the largest trading nations in the world as well as the world's second largest manufacturer, representing a fifth of the global manufacturing output. The US not only has the largest internal market for goods, but also dominates the trade in services. US total trade amounted to $4.93T in 2012. Of the world's 500 largest companies, 128 are headquartered in the US.