The biggest problem standing in the way of Sprint and T-Mobile’s second merger attempt is the fact that they own MetroPCS (now Metro by T-Mobile), Boost Mobile and Virgin Mobile. Together, these three prepaid mobile brands have the dominant share of their market and combining them would pose competitive challenges.

The New York Attorney General’s office has also been concerned about the transaction.

The New York Post reports from sources that Attorney General Barbara Underwood has launched an investigation asking several carriers about what the move could mean for them — a process the Department of Justice has done in its ongoing investigation into the deal. New York intends on sharing its findings with other state attorneys general.

The predominant concern for smaller carriers that buy wholesale access to major networks is that Sprint and T-Mobile will raise rates once they merge. The two have denied that rates will be increased.

New York’s Attorney General’s office has been more bold in pursuing action against companies that have not met their duties to the public. It recently banned Charter Communications, the largest cable provider in the state, from operating because it had not kept up to schedule rolling out high-speed internet in rural areas. It will have to pass on its work to another operator, but will continue to serve until a plan has been formed.