Canada's antitrust watchdog is suing Google to force the breakup of the company’s ad tech unit. In a statement published Thursday, during the US Thanksgiving holiday, the Competition Bureau said a “thorough” investigation had found that Google had abused its dominant position in programmatic web advertising to “maintain and entrench its market power.

The lawsuit, filed with the Competition Tribunal, follows a multi-year investigation into Google's dominance in the digital advertising market. According to the Bureau, Google holds a market share of 90 percent in publisher ad servers, 70 percent in advertiser networks, 60 percent in demand-side platforms, and 50 percent in ad exchanges in Canada.

Canada's antitrust regulator is suing Alphabet's Google over alleged anti-competitive conduct in its online-advertising business, in the latest regulatory challenge to the tech giant's dominance.