Brokers should never allow or ask a client to sign an account opening document in blank, with the information to be completed at a later time. Despite this, brokers sometimes do so, reasoning the practice is more convenient for clients (and brokers) and saves time.
Allowing client documents to be signed in blank can expose you to claims that can easily be avoided. Examples of risks associated with having clients sign documents that are not fully completed include:
Control Over the Clients’ Financial Affairs
Allowing account forms to be signed in blank leaves you in sole control of the content, thus exposing yourself to a claim that the client relied on your discretion and professional judgment in managing his or her accounts. The more control you possess, the greater your duties to your client.