The Federal Trade Commission has ordered the Big Five tech companies - Google, Apple, Amazon, Facebook and Microsoft - to turn over information about any acquisitions they have made over the last 10 years without notifying anti-trust agencies as part of its ongoing probe into antitrust.

In its announcement, the FTC said specifically that it wanted to know about deals that the companies previously did not report to them or the Justice Department under the 1976 HSR Antitrust Act.

Notable deals, like Facebook's purchases of Instagram and WhatsApp and Alphabet's purchase of Motorola, fall within the 10-year window but it is not known whether or not they were reported under anti-trust laws at the time.

A spokesman for the FTC declined to say whether or not those deals were among those that will now be poured over.

'What companies reported or didn’t report is non public. The HSR Act provides a high degree of confidentiality,' the spokesman said.

On Tuesday, the FTC issued Special Orders to the big five tech companies to report any acquisitions that they have not previously reported to them under the HSR Antitrust Act

Alphabet's acquisition of DoubleClick, an advertising software which has enabled its dominance in online ads, and its 2006 acquisition of YouTube, predate the time-frame given.

The FTC said in its announcement that the order will help investigators learn how much of the deals the companies reported to anti-trust agencies in the beginning.

It also said it will reveal whether any of them have intentionally gobbled up competition then hid it from anti-trust agencies.

The order only applies to acquisitions the companies made but did not report to the FTC or the U.S. Department of Justice under the HSR Act.

'Digital technology companies are a big part of the economy and our daily lives.

'This initiative will enable the Commission to take a closer look at acquisitions in this important sector, and also to evaluate whether the federal agencies are getting adequate notice of transactions that might harm competition.

'This will help us continue to keep tech markets open and competitive, for the benefit of consumers,' said FTC Chairman Joe Simons.

The order specifying what information the companies must give is 30 pages long.

It gives them until April to hand over all the paperwork or until February 24 to notify the FTC that they do not have all the paperwork they need to satisfy the demand.