The very same regulatory requirements of making full disclosure cover all financial institutions, whether banking (under different regulatory agencies) or Futures Clearing Merchants (FCM's). So in short, yes, one's house bank or local banker (where one maintains an account) would be required to make similar material disclosures of significant changes in ownership.

At least Domestic US regulated accounts would naturally expect to be notified, not just happen upon some change in the website and some posted notice on same.

After all, your account opening process and their due dilligence efforts look into every legal aspect of their prospective account holders' lives and financial relationships.