There are no specific requirements and the recruiting process is the same. However, although officially most of the companies would say that you don't need any specific business knowledge, in reality, it is hard to solve a case purely based on common sense. So the lack of business knowledge becomes a very common problem among the people with PHD.
Business Acumen is actually about building proper industry and functional knowledge.
Focus on the most common industries in the following priority (sorted by probability of geting a case): 1-retail and CPG; 2-airlines; 3-Telecom; 4-banking; 5-natural resources; 6-tech
There are several sources of information that will help you develop the business sense:
1) Cases - you simply solve 50-70 cases and get a broad knowledge of different industries, common pitfalls and questions. The key here - find good partners who already had case interviews with MBB companies
2) Company reports, equity reports, IB roadshow docs - usually have a good overview of company and industries.
3) HBS cases - quite useful, but not sure if lot's of them available publically. Probably worth buying
4) Industry Books - one good book about airlines with numbers and industry analysis can give you all needed industry knowledge
5) News, Industry blogs
For each industry, you should understand:
- Revenue streams
- Cost structure
- Key performance indicators
- Key revenue drivers
- Industry trends
I strongly recommend drawing the typical structures for each industry - profitability, value chain, etc
Then I will switch to getting functional knowledge:
- Marketing (Brand and trade marketing tools, etc)
- Supply chain (Ops metrics like cycle time and throughput time, distribution and delivery specifics, etc)
- Operations (Process optimization basics)
- Finance (Very basic Finance and Valuation)