Alphabet's Google illegally dominates two markets for online advertising technology, a judge ruled on Thursday, dealing another blow to the tech giant and paving the way for U.S. antitrust prosecutors to seek a breakup of its ad products.

Alphabet Inc.’s Google has been found by two federal judges, in less than a year, to have illegally monopolized critical parts of the internet.

It was the second time in a year that a U.S. court found that the company had acted illegally to remain dominant.