Since 1981, Korea has maintained an unique regulatory framework on economic  concentration. While most countries manage competition laws to discipline the market concentration and its subsequent problems, Korea rather focuses on restraining the aggregate concentration, esp. the economic power of the big chaebols. Recently the inhospitality tradition against the business groups is being aggravated mostly due to the political rhetoric of economic democratization propagated during the 18th presidential race in 2012. Why has the economic concentration been so much social concern in Korea? What makes the Korea specific regulation persistent and even stricter in the globalization era of open competition? In this paper we evaluate the logics and myths behind the regulation in the contexts of economic theory and history. We also estimate theoretically consistent measures of concentration of the 30 large chaebols and test the  corporate hegemony hypothesis, using the data of employments, sales, assets, and diversification indices. The major finding is that various measures used in previous literatures have a feature of ‘quick-and-dirty ones’ in that they lead to significantly upward biases up to 60 percent and a misleading interpretation in the long-term change of economic concentration.