IANAL, but I have google fu:
"Establishing a New Account
Once the necessary documents are received, a new account is typically set up for the beneficiary or estate, at which time securities registered in the name of the deceased person will be transferred. Generally, no account activity (buying, selling, transfer of the account to another firm) can occur until legal authority is established and the new account is opened.
As with any new account, the process will include filling out a new account application that will require the beneficiary to provide some personal information and make certain decisions about the account. Brokers use this information for several purposes, including learning about the new account owner and her financial needs, and meeting legal and regulatory obligations."
http://www.finra.org/investors/highlights/when-brokerage-account-holder-dies
"Establishing a New Account
Once the necessary documents are received, a new account is typically set up for the beneficiary or estate, at which time securities registered in the name of the deceased person will be transferred. Generally, no account activity (buying, selling, transfer of the account to another firm) can occur until legal authority is established and the new account is opened.
As with any new account, the process will include filling out a new account application that will require the beneficiary to provide some personal information and make certain decisions about the account. Brokers use this information for several purposes, including learning about the new account owner and her financial needs, and meeting legal and regulatory obligations."
http://www.finra.org/investors/highlights/when-brokerage-account-holder-dies