America. Citigroup is a global holding company that provides diversified financial services. Headquartered at No.399 Park Avenue, new york, USA, it was established in 18 12. Citigroup is a financial services group with the largest assets, the most profits, the highest global chain and the most comprehensive business types in the world. Citigroup's business includes providing consumers, enterprises, governments and institutions with a wide range of financial products and services, including retail banking and credit, corporate and investment banking, securities brokerage, trading services and wealth management.