Two advertising trade groups have sent a joint letter to the FTC, asking that they pay special attention to how the Google/DoubleClick merger will affect online ad competition, reports MediaPost.

In the letter, the 4As and ANA groups have asked the FTC to dive deep into how the merger may impact the online ad market. They point out that so much innovation has taken place in the world of Internet advertising precisely because of competitive pressure. The deal also has the potential to affect publishers, who will face dramatically fewer choices when looking for ad partners, the groups say.

Not everyone is worried about the deal, though. Some say that while it may herald a period of upheaval, the deal will really only shift lines and definitions. Some even say it will increase publisher and advertiser demand for small niche shops that lack the ballast of a larger company.