Nubank is a digital bank with operations focused in Latin America
Nubank is a Brazilian fintech company of some kind. Cognitect employs the Clojure core developers and also does (did?) consulting work: they were recently acquired by NuBank.
Cognitect does Datomic as well, a pretty awesome database.
Yeah, I believe NuBank uses Datomic heavily, which is part of the reason they acquired Cognitect