(Seattle, WA) -- Portland-based Dalton Management is one of 18 property management firms nationwide accused of using software to artificially increase rents. Willamette Week reports that lawyers in Seattle filed a class action lawsuit last week, against the makers and users of RENTmaximizer software that allegedly allows property managers to trade private market data and artificially inflate rents, using algorithms. The complaint charges that is a violation of federal antitrust law banning collusion. Dalton did not respond to requests for comment. According to its website, Dalton owns 14 apartment buildings in Washington and Oregon.