Most of the world&#x27;s trading is now going through three physical unremarkable buildings: Equinix datacenters NY4, LD4 and TY3 in NYC, London and Tokyo respectively.<p>Inside, there is a mess of server racks installed by major banks and financial companies and everybody else (it&#x27;s not that expensive, by corporate standards, to rent a rack place there), all interconnected by a web of optical fiber. Chaos reigns.<p>These are the places where billions per second change hands.