Mergers to be blamed, too

While waiting for a shuttle to Narita airport this morning, I read The Japan Times (sorry, look for the links yourself, I am blogging from an internet cafe -- got limited time). A report says that the record high US oil prices have something to do with mergers of oil giants. The report cites a rencent study by US General Accounting Office (GAO). Among all, it says that the mergers of Exxon Corp. with Mobil Corp. plus 5 other oil companies since 1990 lifted US gasoline prices an average of 1 or 2 cents a gallon (another big merger was of Texaco Inc. and Shell Oil and Saudi Refining Co.). But, FTC (Federal Trade Commissioun -- FTC) called the GAO study flawed, because "it did not take into account other factors..." -- it is not clear what "other factors" the FTC meant. But isn't FTC suppose to be critical of such mergers?