The Federal Communications Commission (FCC) hit the brakes on its review of a proposed merger between T-Mobile US and Sprint, to allow more time to analyse recently submitted material.

In a letter to the companies, the US regulator said it paused its “informal” 180-day transaction clock, stating additional time is necessary to allow for staff and third-party review of new information and “anticipated modelling relied on by the applicants”.

The FCC was at day 55 of its 180-day review process, but its pause comes following two new submissions made by the companies, and a third which is yet to be posted.

T-Mobile and Sprint made their first formal arguments to secure clearance for the merger, valued at around $26 billion, in June, pushing lower prices, greater competition and 5G leadership as major benefits. The companies first announced the proposed deal in April.

As well as the FCC, the US Department of Justice is also reviewing the deal which, if approved, will shrink the US market from four to three major mobile players.

The FCC explained the applicants submitted “a substantially revised network engineering model” on 5 September, which made its submission more complicated and required more time to review. The second proposal requiring additional review involves details of a business model providing “the financial basis for the projected new network buildout”.

Finally, T-Mobile is also expected to submit additional details on its economic modelling.

“The clock will remain stopped until the applicants have completed the record on which they intend to rely and a reasonable period of time has passed for staff and third-party review,” the FCC wrote. “The Commission will decide whether to extend the deadline for reply comments after receiving the remainder of the applicants’ modelling submissions.”

T-Mobile and Sprint previously stated they expect the deal to close in early 2019.