Final answer:
Professional standards do not permit a CPA firm to own shares of stock in corporations that they audit, regardless of the size of the holdings, as it can present a conflict of interest.
Step-by-step explanation:
The statement that professional standards allow a CPA firm to own shares of stock in corporations they audit if such stock holdings are not material is false. CPA firms must adhere to strict independence rules to maintain objectivity and impartiality in their audit engagements. Owning stock, regardless of the amount, can present a conflict of interest and thus is not permitted in corporations they are auditing. These regulations are designed to protect the integrity of the auditing process and the interests of the stakeholders relying on the audited financial statements.