Because of design issues they have blocked direct trade between players of goods. so you cannot exchange electronics for supplies with a friend.
Here is a Work Around as an example of a Coalition Market
1. Step One: do a trade embargo on everyone but your coalition.
2. Step Two: have everyone in your coalition do the same.
Now when you put something up for sale or to buy only your allies can do it. This creates a trade. You can for example Sell Electronics for $10 and at the sametime put up of a buy order of Supplies for $10. This way you wind up trading the supplies for the electronics and the $ are neutralized.
As a variation on this technique you can also use the mass embargo as a way to find out which player is offering what. When you see something you want to know who is selling it, one by one remove the embargo and see if the restriction comes off, if not put it back on and go to the next person and so forth. Tedious but it will work.
Here is a Work Around as an example of a Coalition Market
1. Step One: do a trade embargo on everyone but your coalition.
2. Step Two: have everyone in your coalition do the same.
Now when you put something up for sale or to buy only your allies can do it. This creates a trade. You can for example Sell Electronics for $10 and at the sametime put up of a buy order of Supplies for $10. This way you wind up trading the supplies for the electronics and the $ are neutralized.
As a variation on this technique you can also use the mass embargo as a way to find out which player is offering what. When you see something you want to know who is selling it, one by one remove the embargo and see if the restriction comes off, if not put it back on and go to the next person and so forth. Tedious but it will work.