Ending Platform Monopolies Act This bill prohibits large online platforms, as designated by the Department of Justice or Federal Trade Commission, from offering certain products or services from another line of business that is owned or controlled by the platform. Specifically, such platforms are prohibited from owning or controlling another line of business that (1) uses the platform to sell products or services, (2) offers a product or service that the platform requires a business user to purchase or use as a condition for access to the platform, or (3) gives rise to a conflict of interest. Under the bill, a conflict of interest occurs when a platform operator's ownership or control of another line of business creates an incentive and the ability for the platform to provide an advantage to the platform's own products or services over those of a competitor on the platform, or exclude or disadvantage the products or services of a competitor on the platform. For example, under the bill, Amazon.com, Inc. may be prohibited from offering for sale on Amazon.com privately labeled products or services (e.g., Amazon Essentials, AmazonBasics, etc.) if designated as a large online platform. Finally, the bill prohibits a director, officer, employee, or agent of a platform from simultaneously serving in the same or a similar role with a formerly affiliated entity.