Study on Competition and the Protection of Personal Data in the Digital Sphere

The Catalan Competition Authority (Autoritat Catalana de la Competència, ACCO) published an official study on competition and personal data protection in digital markets (ES 37/2025), commissioned from Dr. Alba Ribera Martínez of Villanueva University. The study cites research by Aridor, Che, Hollenbeck, Kaiser, and McCarthy as key evidence of the economic effects of Apple’s App Tracking Transparency (ATT) framework. Specifically, the study references their findings that ATT reduced online advertising revenues by 24% to 59% depending on the country, forcing app developers to adapt their business models. The citation appears in the context of analyzing the dual relationship between privacy regulation and competition policy in digital markets, illustrating how privacy-protective mechanisms can have significant competitive implications for businesses operating within app ecosystems.