This article points out a couple of things to me. 1) The scope of Change Management at the NYSE has to be astoundingly huge. 2) A single failed change can cost you a lot in reputation and money.
Either way it sounds like there was a failure in their processes. Because it’s so visible, the next story we are going see is who looses their job over it.
However I still wonder about the story of Anonymous cryptic tweet the day before this failure. Could this be all smoke an mirrors to avoid telling the world they had a breach? I’m not much into conspiracies, however that tweet was rather prophetic.