This document is about an analysis conducted using the PENSIM dynamic microsimulation model to estimate the economic impact of a proposed regulation regarding default investments for defined-contribution pensions regulated under ERISA. The analysis examines the effects of an increase in the prevalence of automatic-enrollment procedures in defined-contribution pension plans, including the impact on pension participation, contributions, account balances, and retirement income. The document provides details on the assumptions and methodology used in the PENSIM runs, as well as the types of output generated for the regulatory impact analysis.