How is regular and continuous supervisory or management services defined in relation to AUM?

Regular and continuous supervisory or management services involve a significant level of engagement in overseeing clients' assets under management (AUM). The definition of this level of involvement typically implies that the adviser plays an active role in managing and making decisions about the investments within these portfolios.

When it comes to having an involvement in 50% or more of securities portfolios, this indicates a substantial commitment to managing a client's investments. Such engagement aligns with the expectation that advisers will provide ongoing oversight and adjust investment strategies in response to market conditions or changes in a client's financial situation. This level of involvement ensures that the adviser actively participates in the management process, which is crucial for fulfilling fiduciary responsibilities and aligning with regulatory standards.

The other options focus on specific types of assets or sectors in asset management—publicly traded securities, private real estate, and mutual funds—each of which can be part of a managed portfolio but do not inherently represent the consistent, overarching involvement indicative of the definition provided in the question. The key feature of regular and continuous supervisory services is the direct and ongoing participation in a variety of securities portfolios, not limited to specific asset types or investment vehicles. Thus, the correct answer highlights the essential nature of active portfolio management that encompasses a significant portion of the client's investments.