Large investors are rushing into the riskiest corporate bonds, frustrated by low interest rates on safer investments and convinced that even companies with shaky finances are in little danger of default.

One sign of that rush: Investors have been buying up corporate bonds with a triple-C rating, a grade that analysts and investors consider highly speculative.

That buying is driving up prices on those bonds and pushing down their yields, which this month fell to 8.187% on a closely watched Bank of America Merrill Lynch index—the lowest level on record. 

This embrace of risky bonds and the retreat from risky stocks reflect a world where interest rates are staying much lower, much longer than most had expected, some investors say. “What we’re seeing is the continued search for yield,” says Matthew Rubin, director of investment strategy at Neuberger Berman, which oversees $247 billion.

The 12-month trailing default rate from low-rated corporate borrowers edged up to 1.7% in April, from a six-year low of 1.57% in March, according to Standard & Poor’s Ratings Services.

The yield gap between junk bonds and U.S. government debt—a measure of the premium investors receive for taking on the risk of junk bonds—has narrowed. On triple-C-rated debt, that gap recently hit 6.97 percentage points, the lowest since November 2007. The all-time low of 4.14 percentage points was hit earlier that year.

A little too many comparisons to 2007 for my taste.