In this type of brokerage account, a surviving tenant of the account does not necessarily acquire the rights (and account assets) of the deceased person. Rather, each tenant in the account can stipulate in a written will how his/her assets will be distributed upon his/her death. Generally, the member ownership in the account is determined on a pro rata basis, meaning that if there are two tenants in the account, each will have a 50% claim on the account's value.
Investment dictionary. Academic. 2012.