In recent years, desired global saving appears to have increased relative to desired global investment, which has made credit abundant and relatively cheap. Federal Reserve Chairman Ben Bernanke has called this a global "saving glut." The International Monetary Fund has emphasized the weakness of global investment relative to global growth.
But whether it's high saving or low investment, the net effect is that large pools of internationally mobile capital have been searching for seemingly scarce investment opportunities, putting downward pressure on long-term interest rates. As investors have searched for higher returns, risk spreads have narrowed, and interest in alternative investments and more innovative investment vehicles has expanded.