Four Big Tech CEOs — Facebook's Mark Zuckerberg, Amazon's Jeff Bezos, Sundar Pichai of Google and Tim Cook of Apple — are set to answer for their companies' practices before Congress as a House panel caps its yearlong investigation of market dominance in the industry.

The four command corporations with gold-plated brands, millions or even billions of customers, and a combined value greater than the entire German economy. One of them is the world's richest individual (Bezos); another is the fourth-ranked billionaire (Zuckerberg). Their industry has transformed society, linked people around the globe, mined and commercialized users' personal data, and infuriated critics on both the left and right over speech.

Critics question whether the companies, grown increasingly powerful after gobbling up scores of rivals, stifle competition and innovation, raise prices for consumers and pose a danger to society.

The four CEOs are testifying remotely for a hearing Wednesday by the House Judiciary subcommittee on antitrust.

In its bipartisan investigation, the panel collected testimony from mid-level executives of the four firms, competitors and legal experts, and pored over more than a million internal documents from the companies. A key question: whether existing competition policies and century-old antitrust laws are adequate for overseeing the tech giants, or if new legislation and enforcement funding is needed.

Subcommittee chairman Rep. David Cicilline, a Rhode Island Democrat, has called the four companies monopolies, although he says breaking them up should be a last resort. While forced breakups may appear unlikely, the wide scrutiny of Big Tech points toward possible new restrictions on its power.

The companies face legal and political offensives on multiplying fronts, from Congress, the Trump administration, federal and state regulators and European watchdogs. The Justice Department and the Federal Trade Commission have been investigating the four companies' practices.