Impact of portfolio diversification on the performance of holding companies based on modern and modernized theories of portfolios

Over the last few years, holding companies have had an increasing impact on the country's capital market, due to their high growth in stock exchanges, both in terms of number and size of capital And diversification is one of the key strategies that hiding companies have been focusing on to increase efficiency and to stay safe from risks; However, the researchers do not agree on this issue. To this end, by using the statistical data of 51 holding companies in the Tehran Stock Exchange (TSE) during 2011-2017, the impact of portfolio diversification on performance based on modern and modernized theories of portfolios investigated. For this purpose, firstly, the variables of the study were examined in terms of their status, Then the least squares method was used for analyzing data and (GMM) and generalized generalized (EGLS) torque (EGLS) for estimating hypotheses.The findings show that diversification in holding companies on performance criteria is based on modern theories and based on modernist theories of portfolios (Jensen, Sharp, Triner, Sortino, Desirability Potential, Omega and Trener, and Jensen Adjustment) has a positive and significant effect.