HSBC said on Friday the United States remains key to its growth plans, a day after announcing the sale of its mass market retail U.S. banking business in a country where it has long struggled to make a strong profit. HSBC's business in the United States will focus on internationally-oriented corporate customers, chief executive Noel Quinn told the lender's annual shareholder meeting in London. "The U.S. is key to our international network and an important contributor to our growth plans," Quinn said.