Firm Designated ID (FDID) is defined in Section 1.1 of the CAT NMS Plan as “(1) a unique and persistent identifier for each trading account designated by Industry Members for purposes of providing data to the Central Repository, provided, however, such identifier may not be the account number for such trading account if the trading account is not a proprietary account; (2) a unique and persistent relationship identifier when an Industry Member does not have an account number available to its order handling and/or execution system at the time of order receipt, provided, however, such identifier must be masked; or (3) a unique and persistent entity identifier when an employee of an Industry Member is exercising discretion over multiple client accounts and creates an aggregated order for which a trading account number of the Industry Member is not available at the time of order origination, where each such identifier is unique among all identifiers from any given Industry Member.” Under the CAT NMS Plan, broker-dealers are required to report the FDID on all Transaction Order events requiring the FDID submitted to the Central Repository and the Central Repository will associate specific customers and their CAT Customer IDs (CCID) with individual order events based on the reported FDID. Given the purpose of the FDID under the CAT NMS Plan, it is important that this identifier be unique, persistent and consistent within the firm and across all vendors and systems the Industry Member may use to report Transaction Order events requiring an FDID to CAT and associated Customer and Account information for the FDID to CAT CAIS, and unique across time. 

A change/replacement in the FDID value associated with a particular trading account would be an isolated event that is only permissible in certain limited circumstances, such as: 

• System migration. For example, Industry Member 1 changes from System A to System B, which necessitates the generation of unique FDID values for accounts, and the system migration does not involve closing the underlying accounts.

• Change of vendors. For example, an Industry Member currently uses an Order Management System (“OMS”) provided by Vendor A but will change to Vendor B’s OMS. Vendor B’s OMS does not support some of the characters supported by Vendor A so the Industry Member must change the FDID. Please see FAQs B53 and Q53.   

• Change in Clearing Firm. For example, an Industry Member changes from Clearing Firm A to Clearing Firm B. Clearing Firm B does not permit FDIDs in the same format as Clearing Firm A so the Industry Member must change the FDID.

• Change in masking methodology. 
  • Changing the algorithm which creates a new FDID value for the account
  • Masking a previously unmasked FDID value
  • Only for proprietary accounts: unmasking a masked FDID value of a proprietary account. 

Note that the above limited circumstances do not include correcting an erroneously reported FDID, closing an account, or transferring the FDID to another CAT Reporter Firm. Please see the CAT Reporting Customer and Account Technical Specifications for Industry Members for more information on these scenarios.

Also, please see FAQ M16 for the requirements when replacing/changing an FDID. 

The same guidance outlined above would apply to an FDID value representing a Relationship Identifier (“Relationship ID”).