CHICAGO (S&P Global Ratings) May 15, 2018--S&P Global Ratings corrected by withdrawing its 'AA-' long-term rating and 'AA-' underlying rating (SPUR) on the Michigan Finance Authority's series 2004A Ambac Insured bonds, issued as part of its series 2004A local government loan program revenue bonds. We incorrectly rated the Ambac Insured bonds portion of the series 2004A local government loan program (LGLP) revenue bonds based on enhancement from the Michigan School Bond Qualification and Loan Program. We originally assigned a rating to the State Qualified School bonds, which were expected to be issued as a separate portion of the LGLP revenue bonds, based on the enhancement. However, the State Qualified School bonds were not issued as a separate portion, and the