The big five tech giants, Apple, Amazon, Google, Facebook, and Microsoft are being asked to declare all business acquisitions over the last 10 years in the USA.
The Federal Trade Commission has started investigating the companies to ensure they do not harm business competition.
Joseph Simons, the FTC chair said, "If during this study, we see that there are transactions that were problematic, it is conceivable we could go back and initiate enforcement actions to deal with those transactions."
This is one of several investigations into the main tech companies in the US.
Why are they being investigated?
In 10 years, each of these companies has dominated the market by buying off potential competitors. When the buy-out is a large company - like Google buying YouTube in 2006, or when Facebook acquired Instagram in 2012 - they had to alert the US government to the sale.
However, acquiring smaller companies in deals worth less than $90 million means a lot of larger organisations do not have to declare this to the government.
In Europe, companies face large fines over acquiring more and more business to ensure the market is kept far and competition isn't bought outright by giants.
The FTC said it expected its request to yield information on "hundreds" of purchases and inform debate about whether the US should change its rules for what kinds of deals are subject to government review.