Difficult to say without more context; alternatives:

- main banking relationship
- local bank (for retail customers)
- account-holding bank (probably too general)

Avoid "house bank" - that's a false friend!

The fact that there isn't a "snappy" English term reflects the cultural difference between the German universal banking system (where many companies often have one major banking relationship), and the situation in Anglo-Saxon countries, for example, where financial services would be provided by a variety of institutions specialised on a particular part of the processing chain (clearing banks, brokers, merchant/investment banks, etc.).

HTH - best regards, Ralf

It usually means the bank used by the firm.

The term "main bank" is very common in Japan, and refers to the bank which stands as guarantor to other lenders should the firm run into trouble.

The term "principal bank" is also used in this context.

Affiliated to a company and acting as principal banker on its behalf
Fwb Finanzen,Banken Börse dtv

Affiliated to a company and acting as principal banker on its behalf
Fwb Finanzen,Banken Börse dtv