On June 3, 2019, the Federal Housing Finance Agency (FHFA) and Fannie Mae and Freddie Mac launched the Uniform Mortgage-Backed Security (UMBS) initiative. The initiative was designed to remedy a long-standing imbalance between the capital markets executions of Fannie Mae and Freddie Mac, which cost Freddie Mac approximately $500 million each year. The UMBS Initiative proved successful, resulting in a single, more liquid, secondary market for each of the GSEs’ securities. The initiative began and was completed under conservatorship, raising potential concerns about whether the initiative can survive antitrust scrutiny post-conservatorship. In this brief, we describe the relevant antitrust law considerations. We conclude that the initiative can survive Fannie Mae and Freddie Mac exiting conservatorship, and we outline some steps the FHFA can take to solidify the current regime.