The article explores the financial motivations behind the production and financing of online misinformation, highlighting that advertising revenue is a significant factor. It finds that companies across various industries frequently advertise on misinformation websites, often through digital advertising platforms that algorithmically distribute ads. The study reveals that consumers react negatively to companies advertising on misinformation sites, leading to a decline in demand for these companies' products or services. Surveys of decision-makers show that many are unaware of their companies' involvement in financing misinformation and express a strong preference to avoid such practices. The research suggests two low-cost, scalable interventions to reduce the financial incentives for misinformation: improving transparency about where advertisements appear and making it easier for consumers to trace advertising on misinformation sites. These interventions could help curb the supply of misinformation by reducing the financial benefits for those who produce and spread it.The article explores the financial motivations behind the production and financing of online misinformation, highlighting that advertising revenue is a significant factor. It finds that companies across various industries frequently advertise on misinformation websites, often through digital advertising platforms that algorithmically distribute ads. The study reveals that consumers react negatively to companies advertising on misinformation sites, leading to a decline in demand for these companies' products or services. Surveys of decision-makers show that many are unaware of their companies' involvement in financing misinformation and express a strong preference to avoid such practices. The research suggests two low-cost, scalable interventions to reduce the financial incentives for misinformation: improving transparency about where advertisements appear and making it easier for consumers to trace advertising on misinformation sites. These interventions could help curb the supply of misinformation by reducing the financial benefits for those who produce and spread it.