Brokerage accounts.

The joint account and comingling of funds create numerous potential problems. The issues largely relate to who owns what portion of each account. Who should be paying the taxes on the income earned in these accounts? Who owns the accounts in the event of one of your deaths? Are there taxable gifts being made between the two of you? If you are putting the money in, and your mother is becoming the owner, there could be a gift tax consequence. What if there is a creditor claim against one of you? How will you establish who owns what portion of what account. If you really wish to have these joint accounts you should seek the assistance of a qualified estate planning attorney to help you properly document and handle these questions.

I appologize. I never answered your direct question. There should be no limit to the amount that is placed in the brokerage account, provided the account is not an IRS or other retirement type account. There can be gift tax implications to the transfers depending on the amounts.