As Google expands its market dominance in search and digital advertising, regulators have grown increasingly concerned about its ability to stifle competition. Last year, the European Commission fined Google a record $2.7 billion for giving its own comparison-shopping service an illegal advantage. In the US, a bipartisan assortment of state attorneys general have urged the F.T.C. to reopen an investigation into the tech giant. Critics argue that Google is benefiting consumers, and that the market can regulate itself.