With roughly $55 billion in assets, Ohio-based Huntington Bancshares is one of the Midwest's largest banks. It conducts most of its operations through its 600-plus branches. Retail banking accounts for about 80% of the company's operating income. The rest is split between auto financing and private banking and insurance. The firm has a vital presence in Ohio, where 55% of its loans reside, followed by Michigan, Indiana, and Pennsylvania (15%, 6%, and 6%, respectively).