The review is still at the staff level and is expected to go through the Bureau of Competition and onto the commissioners over the next several weeks, according to a Dealreporter item.
FTC in late March requested more information about the proposed deal, opening an in-depth antitrust review of the transaction.
The FTC staff are said to have significant concerns about the transaction, Dealreporter said, citing two sources. The regulator is talking to other parties and competitors about their issues with the deal, including Google (GOOGL) and Sony (SONY).
The latest report comes as UK's antitrust regulator on Tuesday set a deadline of March 1 to decide on the purchase of the video game giant.
On Friday, Dealreporter published an item that Sony (SONY) is said to have met with the EC last month to discuss its concerns about the ATVI/MSFT deal. Google (GOOGL) is also said to have worries about the deal and has voiced its concerns to regulators.
Even with all the regulators scrutinizing the deal, Microsoft (MSFT) Chief Executive Satya Nadella remains confident that the $69B deal will get approved, he told Bloomberg in an interview last month.