Google's ambitious, new wave of acquisitions may be hampered by the realities of being one of the largest companies on the web. Google already dominates in many areas and, with each new move, competitors and government regulators are getting more concerned and twitchy. The latest example is the AdMob acquisition, which Google announced last year, but that may be challenged by the FTC (the US Federal Trade Commission) likely with monopoly concerns.

According to a report by Bloomberg citing sources close to the matter, the FTC is now looking to get sworn declarations from Google competitors and advertisers on the AdMob deal, which hasn't been approved by regulators yet. The FTC is concerned that, by buying AdMob, one of the biggest players in mobile advertising, Google will be able to replicate the dominance it already holds on regular online advertising.

The mobile ad market is still very young and volatile, but Google combined with AdMob would instantly become the largest player. Others aren't sitting still either, Apple is making some big moves as well and has made a mobile ad acquisition of its own by offering to buy Quattro. It is also a potentially very lucrative market, as more and more people go online on their mobile phones, thanks in part to the success of Apple's iPhone.

The FTC is looking to get a written declaration from several companies that may indicate that it is looking to challenge the acquisition. This may or may not be the case, but, more often than not, these declarations are in preparation of a move to block the deal or to request different terms if it were to go through.

Google offered to buy AdMob, a big player in the still rather small mobile ad market, last November for $750 million. It looks like Apple was interested in the company, but later went on to acquire Quattro, a smaller competitor to AdMob. There have been those who oppose the AdMob deal and it now looks like the FTC may look deeper into the transaction as well.