Which rule is not set forth in ERISA as a general duty of fiduciary?

The Uniform Principal and Income Rule is not established by ERISA as a general duty of fiduciary. ERISA, or the Employee Retirement Income Security Act, outlines specific fiduciary responsibilities for those managing employee benefit plans, primarily focusing on the financial aspects and the management of plan assets to ensure they are handled in the best interest of the participants and beneficiaries.

The Federal Prudent Man Rule requires fiduciaries to act with the care, skill, prudence, and diligence that a prudent person would exercise in similar circumstances. This rule is essential to establish how fiduciaries should manage plan assets responsibly.

The Exclusive Purpose Rule mandates that fiduciaries must operate solely in the interest of the plan participants and beneficiaries, reinforcing the importance of prioritizing their needs above all else.

The Diversification Rule emphasizes that fiduciaries must diversify plan investments to minimize the risk of large losses, which is critical for safeguarding the plan's assets.

In contrast, the Uniform Principal and Income Rule typically relates to the allocation of income and principal in trust and estate law rather than in the context of ERISA fiduciary duties. It is focused on the management of individual accounts rather than the broader fiduciary responsibilities under ERISA, making it the correct answer to the question.