The amount of debt globally has soared more than 40 percent, to $100 trillion, since the first signs of the financial crisis as governments borrowed to pull their economies out of recession and companies took advantage of record low interest rates.

The $30 trillion increase between mid-2007 and mid-2013 compares with a $3.86 trillion decline in the value of equities to $53.8 trillion, according to the Bank for International Settlements (BIS) and data compiled by Bloomberg. The jump in debt as measured by the Basel, Switzerland-based BIS in its quarterly review is almost twice the U.S. economy.

Borrowing has soared as central banks suppress benchmark interest rates to spur growth after the U.S. subprime mortgage market collapsed and Lehman Brothers Holdings Inc.'s bankruptcy sent the world into its worst financial crisis since the Great Depression. Yields on all types of bonds, from governments to corporates and mortgages, average about 2 percent, down from more than 4.8 percent in 2007, according to the Bank of America Merrill Lynch Global Broad Market Index.