Final answer:
The requirement for a designated broker to own a specific percentage of corporate stock in a real estate firm varies by state regulations; it is not a universal mandate in corporate ownership principles.
Step-by-step explanation:
The statement that the designated broker for an incorporated real estate firm must own at least 10% of the corporate stock can be true or false depending on state regulations. Ownership in a corporation is represented by shares of stock, and while distribution of ownership across shareholders varies, a single individual rarely holds a majority.
State laws and corporate bylaws would dictate the specific requirements for roles within a real estate brokerage firm, including any ownership percentage for a designated broker. It is not universally mandated by corporate ownership principles, but could be a stipulation decided by the state in which the firm operates.