IEX Exchange is building a cloud-first stock exchange that uses the concept of "slowed trading" to eliminate some of the worst practices of HFT. They even use a 38 mile loop of fiber to slow down connections that are "too close".
I'm not sure IEX is cloud-first, that would be a recent development. Their 38 mile fiber gimmick is also kind of silly because they have to provide data to a consolidated feed with no delay.
https://en.m.wikipedia.org/wiki/IEX