Two technical interviews over Skype and one final onsite.
During the first phone interview - with a data scientist and a hiring manager - we went over previous work experience and discussed a specific data science problem at ING.
The conversation was mostly high-level without going into technical details.
Next, was a programming exercise.
This phase required some SQL knowledge (creating, populating and joining tables),
and familiarity with a ML package of your own choice to fit a model to data (eg R or Python with sk-learn).
The onsite (conducted by two managers and no data scientist) was more personal:
ambitions, how you work in a team setting, why you chose ING, why data science, ...