Moody’s Investors Service reported that only one of its rated bond issuers defaulted in April, allowing the global speculative-grade default rate to edge slightly lower during the month, dropping to 1.6% from 1.7% in March.

By dollar volume, the global speculative-grade default rate was unchanged at 4.2% from March to April, representing an approximate 10% increase from its 3.8% level at the start of the year and a more than doubling of the 2% rate of a year ago.

“The 2.6% gap between April’s issuer-weighted and dollar volume-weighted default rates highlights the divergent trends in default risk,” said David Hamilton, Moody’s director of corporate research. “While the dollar-volume measured default rate suggests heightened credit risk, the issuer-based rate remains close to its lowest level in a decade.”

On an issuer-basis, the historical average global speculative-grade rate is 5.1%, far higher than current levels. Moody’s says the issuer-based default rate tends to be a more stable measure of the likelihood of default, as it is less swayed by one or two extremely large defaults.

Moody’s forecast for its issuer-weighted global speculative-grade default rate was little changed in April. Its default rate forecasting model for its issuer-weighted global speculative-grade default rate predicts that the global speculative-grade default rate will rise to a level of 3% by the end of April 2006.

Year to date, four bond issuers have defaulted on a total of $2.2 billion in bonds, according to Moody’s. All the defaulters have been U.S.-based companies. April was the fourteenth consecutive month during which no Moody’s-rated European issuer has defaulted.

The lack of a default kept the European speculative-grade default rate at zero, as it had been in March. The European rate was 1.1% at the start of the year and 1.7% in April 2005. The dollar volume-weighted speculative-grade default rate in Europe also stood at zero from March to April and is down from 0.4% at the beginning of 2006 and from 1.3% in April 2005.