The FTC has filed a request asking for additional information from Arbitron and Nielsen about their proposed merger, a move that could hold up the deal. Ad Age reports that Nielsen withdrew and modified its original notification to the FTC in February, hoping that would ward off such a request. After both companies have given the Commission the information it seeks, the FTC will then have 30 days to make a decision, though it is unknown how long it will take Arbitron and Nielsen to gather the information the government seeks.

However, some anonymous industry sources told Ad Age that they believe a merged Arbitron and Nielsen could monopolize the cross-platform ratings market, controlling the ability to measure TV, radio, digital, print and outdoor media together.

Meanwhile, Nielsen CFO Brian West spoke to Forbes about the Arbitron deal, saying "Arbitron is a big deal for us. Our history has been a tuck-in acquisition strategy, two or three a year, you never break the bank. Adding capabilities or platforms that extend our current business model without going too far afield from what we do, and even Arbitron is in that same philosophy. To pick up two hours of the consumers’ day, those are very unique opportunities; otherwise you do tuck-ins particularly around developing markets." You can read the interview with West here.