This article examines antitrust issues concerning digital platforms equipped with big data. Recent initiatives by the Japanese competition agency are highlighted, comparing them with those by the USA and EU competition authorities. First examined is whether competition among platforms would result in a select few super platforms with market power, concluding that AI with machine learning has augmented the power of super platforms with strong AI-capability, leading to increased importance of merger control over acquisitions by platforms. Next scrutinized is the argument for utility-regulation to be imposed on super platforms, concluding that wide support is limited to data portability, leaving competition law as the key tool for addressing super platforms, its core tool being the provision against exclusionary conduct, enforcement of which, initially, concerns whether to order super platforms to render their data accessible to their rivals. Passive refusal-to-share data needs to be scrutinized under the essential facility doctrine. Beyond passive refusal, platforms’ exclusionary conduct requires competition agencies to weigh the conduct’s exclusionary effects against its efficiency effects. Finally addressed is exploitative abuse, explaining its relation to consumer protection, concluding that competition law enforcement on exploitative abuse should be minimized, since it accompanies risk of over-enforcement.