In turn, this has skewed asset prices, with investors searching for better returns by loading up on riskier debt. This speculative grade -- or junk debt -- refers to bonds that carry a rating of 'BB' or lower from Standard & Poor's or 'Ba' or below from Moody's. They have a higher risk of default compared to investment-grade debt but give a better return for investors as yields are higher.
The issuance of European junk bonds has surged a "phenomenal" 98 percent in the last year, according to a December report by S&P Capital IQ. These junk bonds may have yielded 10 percent in a normal scenario but have fallen to rates of 5 to 7 percent with loose monetary conditions.
(Read More: Junk bond issuance in Europe reaches record in 2013)
But Jones indicated that investment grade bonds tend to be longer duration assets than the high-risk investments. Because of the longer term, effects of inflation on its value would be greater - making it less attractive and thus giving it a higher yield.
"High yield obviously being at the front end of the (bond curve), and pricing off of much lower government bond yields, you tend to find in some indices that high yield actually yields less than investment grade," he said.
However, Michael Browne, an equity fund manager at Martin Currie said that the earnings' yield on equities was greater than the return on these investment grade bonds.