Informal interview, followed by a formal interview with the hiring manager. Big 4 firms also make you fill out a 4-page form where you indicate you academic performance and work history, along with a field mentioning the "reason for leaving" each of your previous employers. This is followed by a question e.g. "What makes Singapore an attractive investment location" - I doubt if anyone actually takes a critical look at the answer though. Interviews are benign - Big 4 staff are not aggressive in their interviews.