Automatic trade offers would trigger if some player defined conditions would be met.

Example auto sell option:

If wood > 200K in storage then put on market sell offer of 50K for 3.5 gold per unit.

Of course system would check for available caravans. Player would have to set all the values and enable auto sell option. 

Example auto buy option:

If food < 50K in storage put on market exactly 2 buy offers for 50K for 3 gold per unit.

System would check for available gold, caravans and number of equivalent existing offers already on the market. If all conditions would be met the offers would be made. In example above if someone would sell 50K food to that town, the system should not make another offer while goods are being transported (otherwise someone could sell to the same town millions of food…)

Such automatic offers would make life easier for many players who run cities on negative food and players could sell their surpluses with less effort. In my opinion much more goods would be sold and bought stabilizing the market prices over the long run.

Alliance players could make internal rules to buy or sell only resources of their alliance. 

Some new research would enable auto trade offers.