When governments borrow money, they sell bonds—essentially IOUs that investors buy. The higher the interest rate (or yield) on those bonds, the more expensive it is for the government to borrow. This week, the interest rate on 10-year US Treasury bonds reached its highest point since 2007, meaning investors now demand more return for lending to the government.
This sharp increase is part of a global trend where bond prices are falling worldwide. The main drivers are strong business investment spending and rising energy prices, both of which are pushing inflation higher. When inflation rises, investors want higher interest rates to compensate for the fact that their money will be worth less in the future. The Federal Reserve will decide this week whether to raise its own interest rates in response.