ADR's are stocks held in a "bankruptcy remote" trust. "Bankruptcy remote" means that the assets and liabilities of the trust are unaffected by bankruptcy of the entity that established the trust. That means that if the bank went belly up, the trust would be unaffected. Obviously, there is some value in a collecting management fees from the trust so the privilege of managing the trust might be an issue in bankruptcy (depending on lots of minutiae).

To find out everything about the trust, go to Edgar at the SEC website, type in the ticker symbol of the ETF, and then search for the F-6 form. The F-6 contains exhibits that will tell you who the custodian is and all kinds of other legal information that is almost never important or interesting.

What happens to the ADR / ADS stock if the custodian bank goes bankrupt?

Also, if you are interested in buying an ADR / ADS stock, how do you find out what custodian bank they are using?

Thanks