Bank Sells Votes on Another Bank

There is a view that I hear expressed occasionally that it is unethical for an investment bank to help activist investors take on companies. The idea is that investment banks are trusted advisers to corporations, meaning mostly the managers and boards of directors of those corporations, and so when they represent activist investors or hostile bidders they are betraying their loyalty to companies/managers/boards as a class. I mostly do not believe this—out of one part “eh it’s all just business” and one part “actually always siding with managers against shareholders betrays your loyalty to the companies themselves, who are technically your clients”—but it’s a thing that people think.

But what about helping an activist investor take on another investment bank? That seems like a more serious betrayal: