In terms of economic fluctuations, it is well recognized that the effects of an economic crisis have a detrimental impact on the entry, growth, decline, and exit of firms. In addition, the magnitude of the impact varies both within and between industries depending on the size and other characteristics of the firm. The economy is going through significant changes due to the emergence of new industries and the decline or disappearance of current ones. This study looks at how big economic events like the COVID-19 pandemic and the global financial crisis have affected businesses and industries. After completing a study at several levels of top international corporations, larger domestic enterprises, and domestic small and medium-sized businesses, it attempts to draw policy implications. First, it is necessary to foster and support top-tier companies to defend against global economic fluctuations and strengthen international competitiveness. In particular, the institution in charge of competition policies domestically and the institution that helps companies improve their competitiveness are different and the focus of policies is distinctive, so comprehensive attention and perspective of policymakers are needed. Second, it is urgent to respond to new issues related to competition policy in the domestic market. The behavior of emerging big tech and platform companies is different from monopoly companies in the past, so consumer welfare is not impaired, but it burdens nearby and other market participants. Therefore, a view that deviates from the focus on monopoly pricing is also essential for competition policy. Third, measures to support global corporate growth and countermeasures against changes in the industrial landscape should be prepared. Investment and R&D expansion at the corporate level is essential for corporate growth, and measures are needed to boost investment in recently emerging intangible assets. In addition, it is important to revitalize the movement of economic resources to cope with changes in the inter-industry landscape accompanied by the crisis. Fourth, policies to revitalize start-ups and closures are required. The decline in new companies' market entry and exit rates is a symtom of an aging economy contributing to the overall decrease in productivity. Therefore, enhancing the revitalization of the corporate ecosystem and expanding the size of enterprises are essential to enhance the dynamics of the economy. Fifth, it is necessary to find an appropriate combination of government roles in times of crisis. In particular, it is important to grasp the detailed status of economic stabilization policies in relation to SMEs, and at the same time, clear judgments on the appropriate size of support measures, the period of support, and the timing of collection are urgently needed.