Part of it is timing, part cost.  If you can fill a building and plan to be there for a while, generally it pays to buy it rather than rent it.  (The renter generally charges a premium to short term borrowers)  For financial accounting&#x2F;engineering purposes (not wanting to show liabilities) firms may do long term leases.<p>This is why it pays for companies like Apple to own their headquarters.<p>Overbuilding the HQ is a classic sign of hubris, similar to putting your name on a stadium.  (Look to Lehman and Bear Stearns for the former, Enron and 3com for the latter)