If you look at the Ally Bank website it states the corporate headquarters is in Detroit. The website lists regional headquarters in Salt Lake, among other cities including Charlotte.
Michael Carpenter, CEO of Ally, per the corporate officer biography previously worked at Citicorp, GE Capital, Travelers Insurance and his own investment firm. He became CEO in 2009. No mention of BOA in his resume.
Jeffrey Brown, who became President and CEO of Ally’s dealer finance division in March 2014, was Treasurer of BOA in Charlotte prior to joining Ally in 2009 in a corporate planning role.
The corporate headquarters is not where the bank is chartered.
Ally Bank has an unusual charter in Utah - not Michigan. IIRC the charter is some kind of mining charter. Very few banks have that kind of charter. It has some restraints in its charter as to what they are able to do as a bank.
The former CFO of Bank of America who went to GMAC Financial and Ally was Al de Molina.
BTW Ally has some very good rates.