Digital platforms have played a crucial role in fostering a platform economy. Our high dependence on digital platforms makes us think about the right level of regulation for them. The U.S. competition authorities and Congress have paid attention to killer acquisitions because of their negative impacts on competition in the U.S. digital platform market. The main interest of digital platforms is to develop the company's core technology, and the acquisition of startups is sometimes seen as a means to replace internal R&D. By acquiring promising startups, R&D projects can secure adequate funding in a shorter time, and gain the advantage of being a market leader. For this reason, GAFAM have strengthened their existing businesses by acquiring startups in high-tech industries. Antitrust regulators and governments have recently paid more attention to the ever-increasing market power of digital platforms in an effort to better understand how digital markets work and promote competition. As a result, the need to regulate many corporate activities, including 'killer acquisitions' by large digital platforms, is being raised, and the direction that regulation takes will have a significant impact on the business strategies of digital platforms and the performance of the platform economy in the future. It is generally characterized by no or low prices on the user side. Because most of GAFAM's M&A transactions do not begin to monetize only until after a large user base has been acquired, they are not challenged by the revenue criteria traditionally used by antitrust authorities in merger investigations. Therefore, in order to regulate corporate behavior, such as killer acquisitions, that restricts competition in the digital platform market, it is necessary to use innovation performance indicators such as patents. Furthermore, a change in mindset is needed in which the digital platform directly bears the burden of proving restraints of competition, rather than the antitrust authorities.