(Bloomberg) -- Senator Elizabeth Warren is doubling down on her criticism of private equity’s involvement in the U.S. housing market as the nation grapples with an affordable-housing shortage.

In letters sent Thursday, the Massachusetts Democrat asked housing firms Progress Residential LLC, Invitation Homes Inc. and American Homes 4 Rent about recent rent hikes, plans to acquire more properties and the number of evictions in recent years. 

Warren and other Democrats have scrutinized Wall Street’s role in the housing market since the 2008 financial crisis. During the pandemic, lawmakers have been on high alert for violations of eviction moratoriums and unfair treatment as Americans struggled financially to stay on their feet.

Warren also expressed concern about automated homebuying practices, which allow companies to buy up properties using algorithms. Bloomberg reported last year that Zillow offloaded thousands of homes to institutional investors.

Read more: Wall Street’s IBuying Spree Is Eating Up Starter Homes

Invitation Homes and American Homes 4 Rent are both publicly traded companies. Blackstone Inc., a leading private-equity firm, took Invitation Homes public in 2017, but later sold its stake in the company. Progress Residential was formed by alternative-investment manager Pretium Partners LLC.

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