Is monopoly in a sector or whole game is possible?

I recently bought all clothing stores and I changed all clothes prices much expensive. The overall market value of prices did not changed. Why is that? I have all supply in clothes but I can’t decide the market price?

Right now, the market price is determined by the customers and how rich they are. If you try to set the prices too high, they won’t shop with you. I guess they order online instead :stuck_out_tongue: