what determines the level of market power a monopolist can exercise
Market power A firm usually has market power by virtue of controlling a large portion of the market. In extreme cases—monopoly and monopsony—the firm controls the entire market. However, market size alone is not the only indicator of market power. Highly concentrated markets may be contestable if there are no barriers to entry or exit, limiting the incumbent firm's ability to raise its price above competitive levels.
Market economy Market economies rely upon a price system to signal market actors to adjust production and investment. Price formation relies on the interaction of supply and demand to reach or approximate an equilibrium where unit price for a particular good or service is at a point where the quantity demanded equals the quantity supplied.