The European Union's antitrust regulator intends to block Amazon's $1.4 billion acquisition of iRobot, the maker of Roomba vacuums, according to a report. The EU Commission informed Amazon of its likely decision during a meeting on Thursday about the proposed deal. Amazon had not offered remedies to address the regulator's concerns that the deal could reduce competition and reinforce Amazon's dominance in e-commerce. Regulators are increasingly worried big acquisitions could give a few companies too much access to customer data and control of certain markets. iRobot shares plunged over 35% in premarket trading on Friday.