As the U.S. government spends an unprecedented amount of money to fix the economy, there is an equally great need to raise the cash to pay for it. This is accomplished through borrowing, whereby Uncle Sam sells Treasury securities of varying maturity. Much of that debt is held by private sector, but about 40 percent is held by public entities, including parts of the government. Here’s who owns the most. Foreign countries listed include private and public investors, according to monthly U.S. Treasury data.