Shell companies are business entities that exist only on paper, with no physical presence, no employees, and no operations. They are often used for legitimate purposes, such as facilitating mergers and acquisitions, protecting assets, or managing investments. However, they are also frequently exploited for illegal activities, such as tax evasion and money laundering, due to their ability to obscure ownership and financial transactions12. Money launderers can use shell companies to disguise the origin of illicit funds, evade sanctions, and avoid the anti-money laundering (AML) measures that financial institutions use to detect suspicious activity23. The process typically involves setting up a shell company in a jurisdiction known for strict privacy laws, such as a tax haven, and then using it to move and hide illicit funds while hiding the identity of the ultimate beneficiaries13.
In this scenario, the fact that the company has been a client for many years does not rule out the possibility of money laundering. The company could have changed its ownership, activities, or risk profile over time, or it could have been involved in money laundering all along without being detected. The fact that the company has added several new subsidiaries that are recently created shell companies is a red flag that indicates potential money laundering. The company could be using the shell companies to hide the source and destination of its funds, or to conceal the identity of its beneficial owners. The institution should perform enhanced due diligence on the company and its subsidiaries, and report any suspicious transactions or activities to the relevant authorities.
How Shell Companies Are Used in Money Laundering: A Detailed Guide
Shell Companies and Money Laundering
The Role of Shell Companies in Money Laundering

Under the Egmont Group Principles, information exchange among financial intelligence units (FIUs) should be conducted freely, spontaneously, and upon request, on the basis of reciprocity. This means that FIUs should be willing to share information without the expectation of reciprocity on how the information will be used. The goal is to facilitate the cooperation and exchange of information among FIUs to combat money laundering, terrorist financing, and other financial crimes.

Economic sanctions are a tool that governments and multi-national bodies can use to prevent the proliferation of weapons of mass destruction (WMDs) by imposing restrictions on trade, financial transactions, travel, or other activities with targeted countries, entities, or individuals that are involved or suspected of being involved in WMD programs. Economic sanctions aim to disrupt the supply chains, funding sources, and incentives for developing or acquiring WMDs, as well as to deter and punish any violations of international norms and obligations regarding WMDs. Economic sanctions can be imposed unilaterally by a country or multilaterally by a group of countries or an international organization, such as the United Nations, the European Union, or the Financial Action Task Force.
ACAMS CAMS Certification Video Training Course, Module 4: Preventing the Proliferation of Weapons of Mass Destruction, Lesson 4.2: Sanctions1 ACAMS CAMS Certification Study Guide, 6th Edition, Chapter 4: Preventing the Proliferation of Weapons of Mass Destruction, Section 4.2: Sanctions2

According to the ACAMS study guide, one of the training elements that should be delivered to new tellers during employee orientation is "large cash transaction reporting procedures" (p. 224). This is because tellers are often the first line of defense against money laundering and have the responsibility to identify and report any transactions that exceed the threshold of $10,000 or are otherwise suspicious. The other options are not relevant for tellers, as they are more suitable for higher-level or specialized staff.
ACAMS. (2020). Study Guide for the Certification Examination for Anti-Money Laundering Specialists (6th ed.). Miami, FL: ACAMS.
AML Requirements for Tellers 1
Deposit Compliance Training Courses 2
As the compliance officer is providing overview of the "bank's anti-money laundering program to a group of new tellers during employee orientation"

Structuring is the practice of breaking down large amounts of cash into smaller transactions to avoid triggering currency transaction reports (CTRs) or suspicious activity reports (SARs) by financial institutions.
CTRs are required for cash deposits or withdrawals of more than $10,000 in the United States, and SARs are filed when there is a reasonable suspicion of money laundering or other illicit activity. By making multiple deposits of less than $10,000 at different tellers, the owner of the retail store is attempting to evade the reporting requirements and conceal the source or destination of the funds. This is a common technique used by money launderers in the placement stage of the money laundering process, when they try to introduce illegal proceeds into the financialsystem. Structuring is illegal under the Bank Secrecy Act and can result in civil and criminal penalties.
6: CAMS Certification Package - 6th Edition | ACAMS, Chapter 2: Money Laundering Risks and Methods, page 43
1: Structuring Cash Deposits, Withdrawals, & Transactions Risk, Golding & Golding
2: Structuring - Wikipedia