The department sent the companies a request for additional information on Monday (10 August), the first formal step in a review process that can extend beyond a year.
In one considered scenario, Amkor may retain a minority stake in the business, which is estimated to worth $1bn to $1.5bn.
The manufacturing project will be carried out through a joint venture, with Sony holding about 60% and TSMC 40%.
UAE's sovereign wealth fund’s potential stake may range from hundreds of billions of yen to about Y1tn.
