The United States has the largest stock market and perhaps the most robust bond market in the world. So not only are US assets important staples for American investors, but they are also very popular for investors living in other countries.
US stocks on Portfolio Charts are considered domestic or local regional assets for US and Canadian investors and are considered international assets for German and British investors. They will be colored red and blue, respectively, in the various charting tools.
US bonds and cash on Portfolio Charts track Treasury bonds and bills issued by the US government.