FINRA Rule 4513

The records must be kept in a separate file or a separate record with a clear reference to the files containing the correspondence connected with such complaints.

It is acceptable to make the records promptly available at the office rather than store them there.

The records must be preserved for a period of at least four (4) years.

For the purposes of this rule a customer complaint is defined as any grievance by a customer involving the activities of the member firm or a person associated with it and connected to:

• the solicitation or execution of any transaction
• the disposition of securities or funds

of that customer.