I applied through college or university. The process took 1 day. I interviewed at BlackRock (New York, NY) in Jan 2014
Interview
Interviewed for the summer analyst position, 1st round. Only one interviewer, who was mostly very professional. Asked mostly fit questions rather than technicals. Typical tell me about yourself, why blackrock, why portfolio analytics. Also asked about my opinion on the markets. The interviewer seemed to be looking for a certain kind of personality.
I had the on campus interview with them. The interviewee asked me a lot of technical questions about the fixed income market, pricing of bond especially. Other questions were just common--why you apply for this position, why you want to work for Blackrock etc