This document is about an advisory opinion from the U.S. Department of Labor regarding the application of ERISA's plan assets regulation to an employee benefit plan's investment in a trust that holds mortgage assets. The opinion concludes that the plan's purchase of pass-through certificates representing a beneficial interest in the trust would constitute an "equity interest" under the regulation, meaning the plan's assets would include its interest in the trust and an undivided interest in the underlying mortgages.