It can have 2 meanings:
As you progress in your career in consulting from a consultant to manager , senior manager all the way to principal, you tend to specialize in specific industries. It could be a manager specialized in an industry
The second one, Bain has “internal roles” meaning, non-client facing roles that develop IP material, support Bain “consulting client facing” teams in industries (e.g. financial services, aviation, etc.) or capabilities (e.g. merger and acquisition, digital transformations, etc.) that they tend to be specialized in after years of consulting and/or consulting experience in the field.
I believe the second interpretation is what you are likely to be looking for :)
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