Big companies living under the shadow of looming antitrust investigations typically tread warily, careful not to give regulators too many ideas — but judging by this week's corporate announcements, Big Tech isn't using that playbook.

What's happening: Despite reports that regulators are interested in probing Big Tech's behavior, Google, Facebook, Amazon and Apple charged ahead this week with acquisitions, software integrations and other grand new programs.

Google's Cloud division announced Thursday plans to acquire data analytics firm Looker for $2.6 billion.

Cloud division announced Thursday plans to acquire data analytics firm Looker for $2.6 billion. Apple this week unveiled "Sign In with Apple" and is requiring iOS app developers that offer Google, Facebook or any third-party authentication to also offer its own single sign-in option.

this week unveiled "Sign In with Apple" and is requiring iOS app developers that offer Google, Facebook or any third-party authentication to also offer its own single sign-in option. Jeff Bezos said at a Las Vegas conference that Amazon plans to make even bigger bets on new business ventures, Wired reports, including its satellite internet project and plans for package-delivery drones.

said at a Las Vegas conference that Amazon plans to make even bigger bets on new business ventures, Wired reports, including its satellite internet project and plans for package-delivery drones. Facebook is pushing ahead with its cryptocurrency plans, courting outside backers to help build trust in its digital payments platform, The Information reports.

Why it matters: In any normal week, these moves wouldn't be out of the ordinary. But coming mere days after the announcement of a bipartisan congressional antitrust investigation and reports of new regulator scrutiny, they raise questions about how seriously the companies take that prospect.

The big picture: Google Cloud is a third-place competitor to Amazon's AWS and Microsoft's Azure in the cloud market, and it's very likely this acquisition was in the works long before the antitrust rumblings in Washington.

Likewise, Apple has long been positioning itself as a privacy-friendly alternative, while Amazon's investment in satellites and drones isn't new.

And Facebook sees an enormous opportunity to seamlessly bundle mobile payments into social media apps.

Yes, but: Right now, those optics aren't ideal. Just as regulators are paying closer attention to charges of anticompetitive conduct that helped these companies amass significant market leverage in the first place, the companies are touting their market power or ambitions to scale their businesses even more.

The other side: All four tech giants have rebutted charges of monopolistic behavior in the past. And for companies of their size, this week's announcements are probably considered non-controversial.

Between the lines: "In an environment where antitrust agencies are paying close attention to you, you want to be careful, so it's interesting that we're seeing these moves," said Charlotte Slaiman, policy counsel at Public Knowledge and former staffer in the FTC's Anticompetitive Practices Division.

It's a key time for the DoJ and FTC, she said, in that news reports haven't indicated the specific scope they're interested in investigating.

As a federal staffer, "once you're in the investigation, you're pretty focused on the conduct you've identified, which is backward looking," she said, adding it appears the agencies haven't yet reached that point.

"When you're looking around broadly at what to investigate, then you'd be very closely attuned to the news. If the news stories coming out are related to the conduct you're already interested in, that will pique the interest on the inside even more."

Go deeper: D.C. antitrust fight takes Big Tech by surprise