Online platforms have dramatically changed the digital economy over the last two decades. They play a prominent role in the creation of 'digital value' that underpins future economic growth in the European Union (EU) and consequently are of major importance to the effective functioning of the digital single market. In a consultation on online platforms, conducted by the European Commission to support its Communication on online platforms, concerns were raised by small and medium-sized enterprises (SMEs) and microenterprises that imbalances of bargaining power between online platforms and small businesses lead to potentially unfair business-to-business (B2B) practices. The objective of the study is to provide additional evidence to help the Commission determine the scope, actual scale and impact of potentially unfair B2B trading practices applied by online platforms beyond the application of competition law (in its present state).