Senator Elizabeth Warren, Ranking Member of the U.S. Senate Committee on Banking, Housing and Urban Affairs, sent letters to 14 major corporate landlords across the single-family, multifamily, and manufactured housing sectors seeking detailed data on their rental housing portfolios and business practices, including landlord-tenant concerns. The inquiry is framed in the context of the Senate’s passage of the 21st Century ROAD to Housing Act, which includes restrictions on large institutional investors’ ownership of single-family housing units. The letters allege that institutional investors can outbid families and worsen housing affordability, while using aggressive or discriminatory tactics and cutting back on tenant protections and maintenance. The materials cite institutional investors owning 450,000 single-family homes nationally, with the five largest investors owning nearly 300,000, a roughly ten percent share of the multifamily market (about 2.2 million homes), and private equity ownership of a majority of manufactured housing communities. They also point to manufactured housing lot rents rising 45% over the last decade, a Massachusetts case alleging “unfair and retaliatory” lot rent increases of over 77% since 2022 and a cumulative 133% hike in new lease lot rents, and federal anti-competition lawsuits related to the use of price-fixing algorithms in multifamily housing. The companies are asked to provide the requested information by 8 April 2026.