I have a joined account with my wife, opened new account for myself, and now she can see on her account my account also :) I did not want her to know about my new account. How much I can get from bank for their mistake?

Sue?
Joint account?

The bank probably didn't make a mistake; you might have opened an account that IS showing on the joint statement. Usually it's a choice you check off on the form when you applied.

Tell your dear wife it's for a new car to surprise her with.

I will assume when you say she can "see" it, you mean online. You did not provide much info, so I will guess a lot to fill in some blanks.

Online banking is geared by the prinscipals social security number. So if your joint account is under your SS#. And if your new account is under your SS# of course it will show up.

Two issues you were trying to hide or hold money back. And you did not do it in a new bank.

I this is what happened, you can not sue them for anywhing.

I will also bet that you didn't read the fine print and didn't notice that your accounts will be linked by default. If you wanted this account to be totally separate you should have asked more questions or, better yet, open it with a different bank.

I don't see any mistake on the bank's part unless you specifically told them to keep this account private and can prove it. And the idea that you could get anything but an apology from them is laughable.