Monopoly form of market also has a downward sloping demand curve where he sells more at lower price.
Explanation:
A monopoly is a form of market where there is only single seller of a particular product in the market and there is no close substitute of that particular product in the market. Therefore there is no supply curve in the monopoly form of market.
A demand curve in the case of a monopoly is also a downward sloping demand curve because a monopolist can sell more by reducing his price of the product.