Studi mengenai kepemilikan blok saham merupakan studi yang berangkat dari kesadaran akan tingginya konsentrasi kepemilikan sahan di sebagian besar negara di dunia. Teori yang mendasari studi mengenai block ownership adalah Agency Problem (Fama and Jensen, 1983). Penelitian ini bertujuan untuk menganalisis pengaruh block ownership terhadap biaya agensi (variabel dependen: S,G,A ratio, Asset Turnover dan Adjusted Short Term Debt Ratio) di Indonesia dan membandingkan pengaruh external block ownership dan internal block ownership terhadap biaya agensi. Penelitian ini menggunakan sampel perusahaan-perusahaan yang termasuk dalam indeks LQ 45 minimal sebanyak 5 kali pada periode 2006-2010. Metode analisis yang digunakan adalah dengan Random Effect Model.Hasil penelitian ini menunjukkan bahwa terdapat pengaruh kepemilikan blok saham terhadap kinerja perusahaan dan terdapat perbedaan antara kepemilikan blok saham internal dan kepemilikan blok saham eksternal dalam mengurangi biaya agensi.

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The study of block ownership is a study which departs from the awareness of the dominance of the high level of ownership concentration of firms in most countries in the world. The underlying theory of research in block ownership is Agency Problem (Fama and Jensen, 1983). This research aims to analyze the effect of block ownership on agency cost (with dependent variables: S,G and A ratio, Asset Turnover Ratio, Adjusted Short Term Debt Ratio) in Indonesia, and to see the difference between internal block ownership and external block ownership to mitigate agency cost. This research used sample data which consist of companies in Index LQ 45 at 5 times listed minimum for the period 2006-2010. The analytical method used is Random Effect Model.

The analysis discovers that there is significant effect of block ownership on agency cost, and shows that there are differences between external block holders and internal block holders in mitigating the agency cost.