Why did Fifth Third buy Comerica?

BANK FIRST National Association 3 Bank of Belleville 2 Bank of Hazelton 6 Bank of Millbrook 10 Bank of South Texas 6 Bank of the Lowcountry 8 Bridge City State Bank 6 BROADWAY National Association National Bank 7 FCB BankS 21 First National Bank in Fredonia 1 First National Bank in Ord 4 Grand Ridge National Bank 6 Libertyville Savings Bank 6 Maynard Savings Bank 1 PEOPLES Bank OF CMRC 7 Private Trust Company, National Association 21 Security State Bank 3 STARION Bank 19 STATE Bank 16 State Exchange Bank 2