On Friday, the United States Department of Justice—along with the attorneys general of eight states—announced a civil antitrust lawsuit against the Richardson-based company RealPage. The firm’s software allows the owners of rental properties to anonymously share the details of their rates, lease terms, vacancies, and other information previously regarded as trade secrets, and to receive suggested rent prices based on an algorithm that aggregates that data. The lawsuit alleges that this violates the Sherman Act, the famous antitrust law, that has been in place since the late 1800s. The implications of the case could be significant. Rent prices nationally have increased an average of 33 percent over their prepandemic rates. The problem is particularly acute in Texas: according to research from Harvard’s Joint Center for Housing…