Moody's upgraded the ratings of Chicago-based MB Financial Inc. and its unit MB Financial Bank NA following its merger with Fifth Third Bancorp.

The rating agency upgraded MB Financial Bank's long-term bank deposits rating to Aa3 from Baa1, short-term bank deposits rating to Prime-1 from Prime-2 and its issuer rating to A3 from Ba1.

The outlook was changed to stable from rating under review.

As MB Financial is now a unit of Fifth Third Bancorp, the rating agency equalized the ratings and assessments of MB Financial to those of Fifth Third Bancorp and of its unit, Cincinnati-based Fifth Third Bank, to MB Financial Bank, to reflect that Fifth Third assumed the liabilities of MB Financial in full.