@ARTICLE{, author = {}, title = {The effect on risk and return portfolio focusing on Iranian banks.( Applied Theory of Winton}, volume = {3}, number = {9}, abstract ={In an efficient banking system, the banks change the small short term low-risk deposits into big long term high-risk loans for major companies that can play significant role in the economy. Of course the method of allocation of these resources, is important and the concentration or diversification can have significant effects so each of them, has own advantages and disadvantages. In this study, the connection between concentration with risk and return of a sample of (2006-2013) has been studied with non-linear U-shaped relation of Winton. non-linear relation of Winton say that increasing of concentration isn’t necessary led to increase return and above the certain level, the relation inverse. The result of this survey show there is a non-linear relation between risk and return and also the rise of concentration in public banks or rise of diversification in private banks led to more return. The results also confirm a negative significant relation between risk and concentration. }, URL = {http://jde.khu.ac.ir/article-1-89-en.html}, eprint = {http://jde.khu.ac.ir/article-1-89-en.pdf}, journal = {Journal title}, doi = {10.52547/jde.3.9.7}, year = {2019} }