What is China's largest company?

I just got an invitation from Ogilvy to join a speech of the president of Azerbaijan later this month in Istanbul during a high-end meeting on energy. Hehe, I think I will not make it. The world is flat, but I would not even have a peek at it when they would offer access over the internet.
What struck me was this in the list of other speakers:

Liu Zhenya, President of State Grid Corporation of China (largest company in China).

The State Grid is a relatively new company was previously known as the (in more than one sense) powerful "State Power Corporation". Former prime minister Li Peng belonged to this conglomerate. The idea was to split off power production and distribution. But I'm not sure whether that really has worked out.
Not sure what kind of measurement is being used to call it the "largest company in China". Anybody can help me out?