What happened

Shares of Amazon.com (AMZN -0.34%) are down 5.8% in the closing minutes of Monday trading, falling as rumors begin to swell about an imminent investigation into the company for anti-competitive business practices.

As Reuters reported today, representatives of the U.S. Department of Justice's (DOJ) Antitrust Division and the Federal Trade Commission (FTC) have been meeting in recent weeks to discuss a division of labor in investigating several tech giants -- Alphabet, Apple, and Facebook among them -- but also Amazon.com.

Red arrow pointing down.

Image source: Getty Images.

So what

According to the report, the FTC will be looking into these questions at Amazon and Facebook. The DOJ will take on investigating Apple and Alphabet. Antitrust concerns appear to lie at the core of the government's moves in all four cases.

No word yet on what either agency intends to do next, but a request for information about the matters that concern them -- followed by a wholehearted response from the companies to "cooperate fully" -- is the way these things normally proceed.

Now what

It's important to keep in mind that just because the government is looking doesn't mean it will open up an official probe into all -- or any -- of the companies. And it's much less likely that it will necessarily find one or more of them guilty of monopolistic behavior.

Just the chance that that will happen, however, appears to be enough to put investors into "shoot first, and ask questions later" mode -- and Amazon is now in their bullseye.