The impact of rating agency reputation on local government bond yields

This study examines a sample of 12,562 dual-rated local government bond issues including 6,104 split-rated issues to determine which rating agency has the greatest impact on yields. Using a database of municipal bond issues from 1986 to 2002, we show that Moody's rated significantly more issues than S&P, and that Moody's ratings were more conservative. However, from 1993 to 1997, there was a reduction in ratings disagreements and in Moody's market share. Beginning in 1995, Moody's received negative publicity related to a Department of Justice anti-trust investigation. Moody's appears to have responded by sharply increasing their relative conservatism in 1997. From 1986 to 1994, Moody's ratings had a greater impact on bond yields than S&P ratings, but their dominant influence on yields disappears in the recent sample period from 1995 to 2002.