Emerging equity markets such az Iran generally need an exogenous liquidity supply in order to accelerate their development. margin trading represents an important vehicle which promotes exogenous supply of market liquidity. Adequately regulated margin trading can increase market efficiency and improve price discovery. margin purchase facilities require regulators, financial intermediaries, and investors to have heightened risk management skills in addition to robust market infrastructure. Despite their standardized features, the actual design and operation of the market infrastructure necessary for margin trading should be country-or market-specific. the key components of this important market infrastructure must be flexible so that they can change over time. traditional pattern of margin trading is The giving loan to brokerage company by banks and then brokerage take loan to the customers against adequate colateral. This paper uses analytical method and field study through questionnaire from financial and Religious Experts and by using Murabaha and Wakala contracts indeed optimization of present pattern in Iran, presents new patterns Financing by the investment fund and Financing by the spv.

Economic uncertainty is an unpredictable changes in economic variables that can have a large impact on other variables and economic entities such as banks and credit institutions, especially in developing countries such as Iran. The purpose of this study was to investigate the effect of economic uncertainty on credit risk, performance and lending decisions of banks. For this purpose, firstly, the effective variables on bank lending decisions were separated into three indicators (credit risk, performance, and lending rates). Also, economic uncertainty was measured using the standard deviation of six variables (exchange rate, annual interest rate, GDP, national income growth rate, ratio of oil sales to national income, tax rate to national income), then research data in the period of five For the year 1390-1394, for 13 banks accepted in the Tehran Stock Exchange, they were assembled by performing different tests, distinguishing between specific bank and macroeconomic variables, from the variability of the research variables. Finally, estimating the econometric model with panel data technology showed that in the first model, the economic uncertainty variable had a positive and significant effect on the credit risk of banks. Also, in the second model, economic uncertainty has a positive effect on the performance of banks, and finally, in the third model, there was no significant relationship between economic uncertainty and the level of bank lending.

This study in first stage, describes the transaction costs imposed on credit institutions and the factors affecting them from the traditional model of transaction cost economics and also introduced the "relationship lending" as a variable that points to reduce the information asymmetry between the borrower and the credit institute. The impact of this variable using Ordered Multinomial Probit Model on the Williamson model will be examined. Credit institutes under this study have been collected as a random sample from banks in Tehran. These banks had been authorized by central bank of Iran till March 2012. The results shows that with the introduction of the independent variable "lending relationships" the final effect of the independent variables "investment in specific assets", "special collaterals", "degree of uncertainty for the credit institute" and "difficulty in measuring employee performance" on variable of transaction costs of lending will be reduced.