Douglas Marr senior vice president of Keliher Real Estate has leased 1185 s/f at 73 Newbury St. in the city's Back Bay, to Atlantic Group International. They have been in the Back Bay for over a decade and needed larger space. Atlantic is a privately held company with offices in Hong Kong and Florida that specializes in business, finance and trade between China and the Americas.Copley Investments is the landlord.