Final answer:
A voluntary corporate action represents the highest operational risk due to requirements for shareholder intervention, communication, and decision-making. Mandatory events like stock splits involve less risk as they are administrative and automatically processed by the company.
Step-by-step explanation:
Among the options provided, a voluntary corporate action has the highest risk from an operations perspective. A voluntary corporate action involves decisions by shareholders, like voting on corporate matters. These actions are not mandatory and require active participation from the shareholders, hence they carry higher operational risks due to the need for extensive communication, management, and decision-making.
In contrast, both a forward stock split and a reverse stock split are examples of mandatory corporate actions that are enacted by the company's management and do not require direct action by shareholders. These activities might change the number of shares outstanding and the share price, but they are administrative and carry less operational risk compared to actions that require shareholder intervention.
A mandatory stock exchange does not typically refer to a corporate action but may imply either the mandatory listing requirements for stocks on an exchange or a situation where shareholders are forced to exchange their shares due to a corporate event such as a merger or acquisition. However, this is less operationally risky compared to voluntary actions as it is usually well-defined and managed by the company.