salam.. The bank refuse investment from certain individuals and companies whose income is questionable. Is it shariah compliant or not?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

The Bank or any other entity cannot be blamed for refusing to deal with whomever it has doubts about the lawfulness of his money, especially if its doubt is based on a proof. Even if the bank has no doubt about one's money, it is not obliged to deal with every individual or company that wants to deal with it.

If that is what you have meant in your question, then we have pointed it out and if you mean something else, please explain it to us so that we may answer you.

Allaah Knows best.