In our upcoming August gathering, we will preview a significant ERISA dispute on the Supreme Court's docket, Anderson v. Intel Corp. Investment Policy Committee, which addresses the pleading thresholds for retirement plan underperformance lawsuits. To prepare for this case, it is essential to trace the historical transformation of the legal concept of "prudence" from a personal, character-based duty to a mathematical and statistical benchmark.
For most of Anglo-American legal history, a trustee's fiduciary duty was defined by moral character and process rather than specific performance outcomes. In the seminal 1830 case, Harvard College v. Amory, the Supreme Judicial Court of Massachusetts established the "Prudent Man Rule." Justice Samuel Putnam wrote that fiduciaries must "conduct themselves faithfully and active with sound discretion," observing how "men of prudence, discretion and intelligence manage their own affairs." Prudence was understood as a qualitative, process-oriented virtue. If a trustee conducted careful inquiries and avoided reckless speculation, they could not be held liable for losses caused by general market downturns. The law judged the integrity of the trustee's mind, not the numerical variance of the portfolio.
With the rise of Modern Portfolio Theory (MPT) in the mid-twentieth century, this qualitative standard underwent a radical shift. MPT mathematically defined risk not as the danger of individual speculation, but as the statistical variance of an entire portfolio relative to a market index. Prudence was no longer a matter of looking a trustee in the eye and evaluating their discretion; it became a statistical calculation. Under the modern Prudent Investor Rule, fiduciaries are expected to diversify assets and optimize risk-adjusted returns against objective benchmarks.
This history is the crucial backdrop for Anderson v. Intel. The Supreme Court must decide whether a retirement saver can sue a fiduciary based on poor performance alone, or if they must identify a specific, meaningful benchmark that proves the manager deviated from the statistical peer group. In August, we will debate whether this modern, mathematical definition of prudence protects savers by enforcing rigorous standards, or if it shields negligent managers by setting an impossibly high procedural bar for lawsuits.