Common market confusion (Golden Rainbow)

I had noticed for time my corps are buying outside on the world market for supplies. I found this suprising because I can produce 75 percent or more of what they need. I finally clicked on Common Market button. Now I see that most of my corps are buying supplies locally. Ever since I did that seems things have gotten worse. I thought that corps being self sufficient would be a good thing. Any help here?
Irishtiger
"Untited Brewers of Newcastle"

Cancel all common and local contracts. They are worthless because of how the world market is set up compared to the common/local market.

Irishtiger, I HIGHLY suggest you start using the Simcountry chat, instead of making 4-5 new threads every day on different topics.

I'm only saying that, to help you, as you can get responses to all of your questions MUCH faster that way.