What country has the highest GDP?

The United States is a highly developed country, and its economy accounts for approximately a quarter of global GDP and is the world's largest by GDP at market exchange rates. By value, the United States is the world's largest importer and second-largest exporter. Although it accounts for just over 4.2% of the world's total population, the U.S. holds over 30% of the total wealth in the world, the largest share held by any country.

The United States has the world's largest GDP at market rate exchange rates.  The United States also accounts for approximately 25% of the global GDP.  It is the largest importer and second-largest exporter.  Having only 4.2% of the world's population, the United States holds over 30% of the total wealth in the world, which is the largest share held by one country.