The European Union’s antitrust regulators are set to launch a full-scale investigation into Amazon.com Inc.’s (NASDAQ:AMZN) $1.7 billion acquisition of robot vacuum cleaner maker iRobot (NASDAQ:IRBT), Reuters reports.

EU’s Antitrust Investigation

Following the end of its preliminary review of the deal on July 6, the European Commission is expected to initiate a four-month investigation. Despite the odds being high against it, Amazon has a final chance in the coming days to convince the EU competition watchdog that the deal is pro-competitive.

Impact on Amazon and iRobot

News of the impending investigation led to a roughly 10% drop in iRobot shares, their largest percentage drop since February of the previous year. Amazon shares also saw a reduction in gains after the news was published.

Global Antitrust Concerns

Antitrust enforcers worldwide have become increasingly cautious about Big Tech’s acquisitions of smaller rivals. Concerns revolve around the accumulation of vast amounts of data by a few companies and the potential for large companies to leverage their dominance into new markets.