Debt Downgraded Ahead of This IBM New York Office Exit: Bond rating firm KBRA has downgraded ratings for all classes of a commercial mortgage-backed securities deal holding a $273.5 million loan on 51 Astor Place in New York's Greenwich Village neighborhood. IBM Watson Group, the largest tenant in the 400,000-square-foot office building, is expected to vacate its nearly 144,000-square-foot space there at the end of the year, according to KBRA.