If you asked me that 15 years ago, I'd say "no". In hindsight, it sort of makes sense given their objective of increasing time spent online and the quality of the experience.

The proposition here is that nubank will be the first bank to successfully turn into a software vendor. Maybe my worries will be nothing in 10 years, but no one can say its an obvious outcome.

Nubank already ships software, Cognitect is already a healthy consultancy, no particular reason to kill either one. Surely we can agree that banks also care about good UX? Nubank in particular is known for it.

(I appreciate that you may not have heard of Nubank but I don't think calling them "unknown" is fair. They have attracted a literal billion in funding in a little over a year. They have over 10 million users.)

Bloomberg and Jane street (not banks but still finance). They don't own OCaml but are heavily involved in its development.

Bloomberg has sponsored BuckleScript in the beginning, but now it is sponsored by Facebook. Other than that their influence on OCaml development is minimal (and technically BuckleScript is a fork of the OCaml compiler).