According to a story in the Wall Street Journal, the US FTC may be gearing up to fight the acquisition of AdMob by Google. Here's what the Journal is reporting:

The FTC has assembled an internal litigation team to prepare for a possible effort to block the deal, according to people familiar with the matter. It also sent letters to AdMob's competitors asking them to testify in sworn statements about the potential impact of the purchase, according to several other people with knowledge of the effort.

In addition, the agency has briefed Congress on its concerns about the deal, the people familiar with the matter said.

The FTC's staff hasn't made a final decision to try to halt the AdMob deal, and its five commissioners haven't yet voted on the issue. Google lawyers continue to meet with the agency's staff to argue in favor of the acquisition, and the two sides could yet come to an agreement that assuages the FTC and preserves the deal.

While the transaction would create a truly formidable competitor in mobile advertising (when you look across platforms) it doesn't diminish competition in mobile (in my view) and would be unlikely to affect ad prices. These are the two formal concerns of classical anti-trust analysis, as I understand it. 

The irony is that most of AdMob's competitors celebrated the deal as boosting the profile of mobile advertising and their own valuations. That's not typically the case in an anti-trust situation. 

There would appear, however, to be a general concern about Google's size and strength and the possibility that the company would come to rule an emerging ad market. In terms of the impact on competition and prices, the deal would be unlikely to damage the market. Yet there's no question that Google would be stronger in multiple ways in mobile with AdMob than without. 

As a related matter, Apple is supposed to reveal (among other things) details of its ad strategy tomorrow. Google has pointed to Apple-Quattro several times to indicate there's healthy competition in the mobile ad market. And indeed there is. 

It's going to be really interesting to see what the FTC does here because it has a potentially tough case if it chooses to block the deal.