Not surprising, but not good.
"Credit-rating companies routinely award higher rankings to debt issued by banks and corporations that pay them the most, a conflict of interest that may escape Congressional efforts to change the way they do business.
Bonds from countries and cities that pay about half as much as issuers of less creditworthy debt are “rated more harshly,”
and later:
"The report, titled “Credit Ratings Across Asset Classes: A=A?,” was co-written by Jess Cornaggia, assistant finance professor at Indiana University’s Kelley School of Business, with his wife, Kimberly J. Cornaggia, an associate professor at American University’s Kogod School of Business and John E. Hund, an assistant finance professor at Rice University’s Jones Graduate School of Business.
“We disagree with the study’s methods and findings,” said Michael Adler, a spokesman for Moody’s."