Assured Guaranty Ltd. President and CEO Dominic John Frederico believes a Moody's rating on Assured Guaranty Corp. is not "essential" to the company anymore, and is asking the rating agency to withdraw its rating.

S&P Global Ratings recently reaffirmed its AA financial strength ratings on Assured Guaranty Ltd.'s principal operating subsidiaries following a comprehensive annual review, and Kroll Bond Rating Agency also reaffirmed its AA ratings for Assured Guaranty Corp. The outlooks are stable.

"As for Moody's, we have long disputed their subjective methodology and their disregard for the quantifiable improvement in our financial strength," Frederico said on a call to discuss fourth-quarter 2017 earnings.

After securing stable outlooks from S&P and Kroll, a Moody's rating on Assured Guaranty Corp. is no longer considered as important, the CEO said.

In May 2017, Frederico said that Moody's had not agreed to Assured Guaranty Corp.'s request to withdraw its ratings despite terminating the rating agreement in January 2017. The executive has argued that a Moody's credit opinion on Assured Guaranty Corp. is based on what he said were subjective, nonquantifiable and elusive standards.

S&P Global Ratings and S&P Global Market Intelligence are owned by S&P Global Inc.