When a welfare loss occurs because of monopoly?

Welfare loss in a monopoly occurs when the monopolist sets prices above the marginal cost of production, leading to reduced output compared to a competitive market. This results in a deadweight loss, where potential transactions that could benefit both consumers and producers do not happen. Consequently, consumer surplus decreases, while the monopolist captures a larger portion of economic surplus, leading to inefficiencies in resource allocation and a net loss in societal welfare.