Abstract

The State of Wisconsin Investment Board (SWIB) made headlines in 2024 with a landmark investment in spot Bitcoin ETFs, and again in 2025 when it divested. This real-world case ignited a policy debate, with critics decrying crypto as a “risky gamble” for public pensions. But what is the actual fiduciary lesson from Wisconsin’s foray? This paper provides the first comprehensive, portfolio-level empirical test of these claims. Simulating SWIB’s approach, we measure the impact of a 0.5% allocation to a Bitcoin ETF within standard public pension portfolios from January 2024 to September 2025. Our results show that such a de minimis allocation resulted in no material increase in portfolio volatility or maximum drawdown, while consistently offering a marginal improvement in risk-adjusted returns. Nearly identical results were found for a comparable gold allocation. The central lesson from Wisconsin is clear: categorical opposition to crypto is not supported by portfolio-level metrics and is misaligned with prudent fiduciary principles. The path forward lies not in blanket prohibition, but in a policy framework centered on transparency, proportional governance, and modernized fiduciary education on alternative assets.

Keywords: Bitcoin, Cryptocurrency, Portfolio diversification, Fiduciary duty, Pension fund, Institutional investing