The United States has the highest GDP in the world by far (over $13 trillion), and has experienced steady economic growth over the years. In today's era of globalization, U.S. investors and corporations continue to have great influence in the world's economy. The U.S. dollar is by far the most widely traded currency in the world. It is often the "vehicle currency" in many currency transactions (meaning two currencies are traded against the U.S. dollar rather than directly against each other, a common market practice). Because of the U.S. influence on the global economy, any changes in U.S. economic status or the value of U.S. dollar are closely monitored by market participants across the globe.
Your capital is at risk. Losses can exceed investment. Leverage trading is high risk and not for everyone.