Based in New York, Citibank is the primary banking operation of financial services behemoth Citigroup. Of the company’s nearly 1,400 offices, branches are concentrated in Texas, New York, California and Illinois. Citibank offers retail and commercial banking services, including online banking, deposits, credit cards, mortgages and personal loans. Investments are offered through affiliate Smith Barney. Student loans are doled out through the Student Loan Corporation. Citibank also offers the popular ThankYou rewards network for credit cards and retail sites.