E.U. Takes Aim at Big Tech’s Power With Landmark Digital Act

The European Union was expected to finalize this week one of the world’s most far-reaching laws to address the power of the biggest tech companies, putting in place rules that will affect app stores, online advertising, e-commerce, messaging services and other everyday digital tools.

The law, called the Digital Markets Act, would be the most sweeping piece of digital policy since the bloc enacted the world’s toughest rules to protect people’s online data in 2018. The legislation is aimed at stopping the largest tech platforms from using their interlocking services and considerable resources to...