What are the welfare effects of monopolies and oligopolies?

Monopolies and oligopolies can lead to welfare losses due to reduced competition, resulting in higher prices and lower output compared to competitive markets. Consumers often face limited choices and may pay more for goods and services, leading to a decrease in consumer surplus. Additionally, these market structures can lead to inefficiencies, such as reduced incentives for innovation and lower overall economic welfare. However, in some cases, monopolies may achieve economies of scale that can benefit consumers if cost savings are passed on.