"The spreads are factoring in a pretty draconian scenario in the economy," Keenan said. While high-yield bonds are a good relative investment, it "may not be a good short-term trade because of policy risks," Keenan said. "There's still a tremendous amount of systemic risk."
The U.S. economy may end the year with an expansion rate of 1.6 percent compared with 3 percent for 2010, according to the median estimate of 66 economists surveyed by Bloomberg.
High-yield bonds lost 0.4 percent this month following declines of 4 percent in August, Bank of America Merrill Lynch index data show.
Notes graded BB by S&P and Moody's have outperformed the lowest-rated junk debt for five consecutive months as investors continue to shed risk tied to companies that rely most on economic growth to reduce debt, the data show.
Bonds rated CCC and lower have lost 10.6 percent since the end of April following a rally that increased the value of the debt by 123.9 percent since the end of 2008.