The Multiemployer Pension Reform Act (MPRA) allows multiemployer plans facing insolvency to apply for approval from the Treasury to cut accrued benefits of plan members to prolong plan solvency—a departure from the benefit protections of Employee Retirement Income Security Act. To assess the law's impact, this paper models Central States Teamsters – by far the largest – plan to have applied under the new law to reduce benefits. Using a stochastic model of future investment returns, the probability of insolvency within 10 years drops from 50% (without cuts) to 6% (with cuts). While benefit cuts increase the overall welfare of participants by extending the plan's life, the welfare of younger retirees (under age 75) worsens and welfare of workers improves.

The financial market assumptions of the Pension Benefit Guaranty Corporation (PBGC)'s Pension Insurance Modeling System model are critical inputs to simulations for most apparent uses of the system. They currently appear to be based on a reduced form, ‘classical’ approach to assessing and forecasting the distribution of returns on various classes of input assets, allowing for a fairly sophisticated and useful approach to understanding simulated distributions of potential pension insurance outcomes as well as the net financial status of the PBGC. This technical note discusses some of the capital market side assumptions utilized in the model. It also comments on important related assumptions including the assumed asset allocations of insured plans, making suggestion for possible modification of input assumptions of the model to reflect time variation in financial market return behavior as well as time variation in observed plan allocations.