Speaking to the Welsh Affairs Select Committee, CC chief executive Martin Stanley said: "If you are ambitious, and you've got a good product, you can grow. There are no barriers, you don't hit anything that says you cannot go any further."
He added that the Commission was likely to do "the minimum necessary" to change the market. "In most of the country consumers have lots of choice," he said.
There was better news for suppliers, with Stanley suggesting that although the existing supermarket code of practice was working reasonably well, "there are holes in it and we are minded to do something about it".