This chapter explores the structural and operational characteristics of Korean chaebols, with a focus on ownership concentration, corporate governance, business diversification, and internal transactions—factors that have drawn significant political and economic scrutiny. It provides a historical and regulatory overview of the measures introduced to mitigate the risks associated with chaebol dominance. The analysis evaluates the economic rationale behind these regulations, particularly in relation to fictitious equity investments such as cross and pyramidal shareholdings, the functional role of intercorporate ownership, excessive diversification, and profit tunneling. The chapter concludes with case studies of regulatory interventions addressing unfair intra-group subsidization, including notable examples such as Samsung SDS, Hyundai Glovis, Hanjin KAL, Hanwha Solution, and Samsung Wellstory.