If apartments are 25% vacant on speculation grounds, that&#x27;s quite a bubble.<p>I don&#x27;t intend to do it, but for curiosity&#x27;s sake: How does one go short on houses?<p>&quot;I&#x27;ll pay you to let me borrow your house and sell it to someone else. Later, I&#x27;ll get you an equivalent house.&quot; Never heard of anyone doing such a thing, but at the right up-front payment, I bet someone would take the deal.