The Financial Action Task Force (FATF) Recommendation that should cause an anti-money laundering specialist the most concern is B: Financial institutions should not keep anonymous accounts. This is because anonymous accounts are accounts that are opened or maintained without verifying the identity of the customer or the beneficial owner, or with fictitious or incomplete information. Anonymous accounts pose a high risk of money laundering and terrorist financing, as they can be used to conceal the origin, destination, and purpose of illicit funds, and to evade the detection and reporting of suspicious transactions. Therefore, the FATF Recommendation 10 requires financialinstitutions to identify and verify the identity of their customers and the beneficial owners, and to prohibit the opening or maintaining of anonymous accounts or accounts in obviously fictitious names1.

The other options are also FATF Recommendations, but they are less relevant or applicable to the scenario. Option A: Financial institutions should not warn their customers when information relating to them is being reported to the competent authorities, is the FATF Recommendation 21, which aims to prevent tipping-off, i.e., alerting the customer that they are being investigated or reported for money laundering or terrorist financing. However, this does not directly address the issue of identity verification or anonymous accounts2. Option C: Financial institutions should maintain all necessary suspicious transaction report records on transactions, both domestic and international, for at least 5 years, is the FATF Recommendation 11, which aims to ensure that financial institutions have adequate and consistent records of their customers and transactions, and that these records are available to the competent authorities when needed. However, this does not prevent the opening or maintaining of anonymous accounts in the first place3. Option D: If financial institutions suspect that funds stem from criminal activity,they should be required to close the account, is not a FATF Recommendation, but rather a possible action that financial institutions may take in accordance with their risk assessment and policies. However, the FATF does not mandate or recommend the closure of accounts as a general rule, and advises that financial institutions should consult with the competent authorities before taking such action, as it may alert the customer or compromise the investigation4.

1: FATF Recommendation 10: Customer due diligence, 1 2: FATF Recommendation 21: Tipping-off and confidentiality, 2 3: FATF Recommendation 11: Record keeping, 3 4: Frequently Asked Questions (FAQs) related to Suspicious Transaction Reporting, 5