If that's the case, would you be willing to drop an example of a banking company there that's doing node.js (that would be the first time for me hearing anything about a large scale deployments of that tech in banking)?
Lloyds Banking Group is organizing JavaScript meetups[1] in Edinburgh. They even invite node.js core contributors on some talks. They're investing into full-stack JavaScript teams for the user facing applications.
JP Morgan and Chase. Even from the time I worked there was quite a lot of new projects created in node.js. Node.js became approved tech within company. Java is still most popular but teams have quite a bit of autonomy in choosing technology.
I also had RBS and Tesco Bank requiters contacting me for JS Full-stack jobs.