Yields on both the one-month and three-month Treasury bills dipped below zero Wednesday, a week and a half after the Federal Reserve cuts its benchmark rate to near-zero and as investors have flocked to the safety of fixed income amid general market turmoil.

The U.S. now joins large swaths of Europe and Japan that also have negative-yielding debt.

In Germany, the move was even more prevalent, with all government fixed income instruments except the 30-year bond carrying rates below zero. Denmark, France and Sweden are among other European nations also in the category.

Negative yields are largely a function of demand, as prices and yields move in opposite direction for bonds. Investors pay a large premium above par on the bonds and can receive less than their initial investment at maturity. Deposit rates also can be negative.