“Most favored nation” (MFN) is a term private funds lawyers have long used to describe the ability of a private fund investor to piggyback off of the terms negotiated by other investors. Although MFNs are deeply ingrained in the private funds industry, their use may evolve in light of changes introduced in the finalized private fund rules (Private Fund Rules) issued on August 23, 2023. Specifically, the Private Fund Rules contained a new private fund adviser preferential treatment rule pursuant to Rule 211(h)(2)(3)(a) (Preferential Treatment Rule) under the Investment Advisers Act of 1940, which may alter how MFNs are used by both registered and exempt advisers going forward, assuming it survives legal challenge. In a guest article, Sidley Austin partner Jennifer A. Spiegel discusses how the MFN concept originated; reviews how the recent past has shaped MFN practices for closed-end, or illiquid, funds; summarizes why the Preferential Treatment Rule will mandate certain changes to those practices; and anticipates how these changes may affect MFN practices going forward. See “Final Private Fund Reforms: Overview of the New Rules and Analysis of the Restricted Activity Requirements (Part One of Three)” (Sep. 21, 2023).