I can confirm Bloomberg does this, u/quackware is correct. I went through the program myself recently, and it's actually a very nice dive into a unique full stack -- and because you take the training with a large group of peers, it's a good way to network as the company/make friends in a new location, especially if you're fresh out of a grad or undergrad program.

I know there were some issues with the program in the past (for instance, at one point you had to maintain at least an 80% "grade" in the program or you'd be cut loose from the company) but Bloomberg has really invested in the program recently and it's much more trainee-friendly these days. Lots of emphasis on cooperation and teamwork, and even though there are some solo timed "assessments" they're about the right level of challenge, and the goal is understandable -- they're there so the trainers can get a feel for what lessons work and what lessons need fixing.

Anyway, it was invaluable to me. I can't imagine jumping straight into a dev role at a company fresh out of college.

Most likely Bloomberg, as their tech stack is a bit unique and requires some specialized training (in addition to general C++ and JavaScript training)

Not the parent, but the US-based Financial Services company I work for also does a 3 month training scheme for their new graduate hires. Better yet, they brought all of their graduates worldwide out to the same place - so we've now got a worldwide network of people who started at the same time as us and that we've spent months with together.

Alas, due to cost (airfare and accommodation for everyone for 3 months adds up to a lot!) they've now scaled it down to just within each region rather than globally - so all of the NA graduates will train together, all the EMEA ones etc. Not quite globe-spanning as before, but still 3 months long and with people from other locations, just not all locations.