The process took 1 day. I interviewed at Bloomberg (New York, NY) in Nov 2009
Interview
Contacted by and HR representative. She was friendly and asked what I knew about the position and what I knew about Bloomberg besides the Bloomberg Professional Service. She said that I would hear back in a week or so. I asked questions and she answered them in detail explaining the position more thoroughly.
Begins with a personality assesment that also includes puzzles meant to test pattern recognition. The assesment and the personality quiz takes about 30-40 minutes and requires no preperation before hand.
First was Hireview, 1 Hour interview with two team leaders, and assessment centre, consisting of tests, networking, and a final round interview with two team leaders from analytics and sales departments respectively.
Multi step interview process, they have you submit a recorded video interview, then you get selected for a virtual super day where they interview a bunch of candidates at once, then you get an in person. Know about finance and know as much as you can about Bloomberg and its business. Have a good take on AI in finance.