That’s true for small to medium-sized companies. For large and very large companies, you should consider than many OWN A LOT OF THEIR OFFICE REAL ESTATE, internationally, often in the billions of dollars worth. A large chunk of their assets are in the office buildings they own, and if they become worthless the company stands to lose a lot. Not to mention that they will often borrow against the value of the buildings, and as a collateral if the value drops significantly the banks might decide that they have to pay back the excess portion of their loan immediately or put up more collateral (margin call).