Which of the following actions violates FINRA rules regarding selling away?

Engaging in private securities transactions without written prior consent violates FINRA rules regarding selling away because it involves a registered representative conducting business outside of their firm without the necessary disclosure and approval. FINRA regulations require that representatives obtain written consent from their firm before participating in any private securities transactions, which includes any investment activities outside the scope of their employment with the firm. This policy is in place to ensure that firms are aware of all the business activities their registered representatives are engaged in, allowing for proper oversight and compliance with regulatory standards, protecting both the firm and its clients from potential conflicts of interest or fraud.

The other options do not constitute violations of selling away. Conducting business during firm hours is permissible as long as it is firm-related activity. Soliciting investments from friends is not inherently a violation unless it involves private securities transactions without the firm's consent. Using firm resources for personal trades could violate other regulations regarding the use of firm property, but it does not specifically relate to selling away. Therefore, the emphasis on obtaining prior written consent before engaging in private transactions is crucial to maintaining compliance with FINRA rules and safeguarding the integrity of the securities industry.