I applied on Bloomberg's website directly. Did not hear back from them for 2 month. Then Received an email an HR person asking me to do a IQ/Technical Aptitude test. The online test was C/C++ based, and it was very difficult and very technical. I don't think I got that much right. But 2 or 3 weeks later I received another HR email requesting a phone interview.
The phone interview itself lasted about one hour. It was conducted by two technical people. It was about 15 minute small talk and background talk from both the interviewer and myself. Then 15 minute on the resume (past projects, mistakes made, etc etc). Then last 30 minutes on technical questions, on C, C++, algorithms and coding questions. At the end, they told me HR will get in touch with me regradless of the result.
1 Week later, HR got in touch and requested an in person interview. They Flew me to New York. Interview started at 10 am, HR interview first (1 interviewer, generic behavioural questions, past experiences), 30 minutes. Then technical question round 1 (two interviewers, C, C++, puzzle solving, past projects, ended with some works they do at Bloomberg, then Q&A). Technical round 2 (means you passed first stage, or else you wouldnt' get to round 2, and would be sent home already. 1 senior manager, C, C++ technical right away, algorithms, design patterns, Q&A), 45 minutes or 1 hr. Then HR interview 2 (mostly chatting, and talking about salary expectation, and stuff).
I heard back with an offer the very next day (I hear from my colleagues that this is not typical, normally takes a week to three weeks for them to decide.