درخت حوزه‌های تخصصی

This paper focuses on two main issues that are based on two important concepts: exponential Levy process and minimal entropy martingale measure. First, we intend to obtain risk measurement such as value-at-risk (VaR) and conditional value-at-risk (CvaR) using Monte-Carlo methodunder minimal entropy martingale measure (MEMM) for exponential Levy process. This Martingale measure is used for the exponential type of the processes such as exponential Levy process. Also, it can be said MEMM is a kind of important sampling method where the probability measure with minimal relative entropy replaces the main probability. Then we are going to obtain VaR and CVaR by Monte-Carlo simulation. For this purpose, we have to calculate option price, implied volatility and returns under MEMM and then obtain risk measurement by proposed algorithm. Finally, this model is simulated for exponential variance gamma process. Next, we intend to develop two theorems for implied volatility under minimal entropy martingale measure by examining the conditions. These theorems consider the asymptotic implied volatility for the case that time to maturity tends to zero and infinity.

The purpose of this study is to investigate the effective of investment inefficiency and cash holding on CEO turnover. This study applies logistic regression method estimator to investigate the relationship between examine the effective of investment inefficiency and cash holding on CEO turnover of 1,309 firm-year observations in Iran for the period of 2009-2019. According to positive relation between mentioned variables, the managers' opportunism increases investment inefficiency and cash holdings of the company because inappropriate managerial decisions lead to increased risk of wrong selection for investors. In the present study, the weaknesses caused by the ambiguity of investment efficiency in market performance-based statistical models are compensated and partially covered by quantifying the relationships and implementing models. The Results will aid policy makers to evaluate disclosure rules and firms to managing their information. The study is based on the corporate accounting and financial literature and examines CEO behavioral changes that can be applied to investors, managers, standardization committees, and legislators. Unlike other research, CEO turnover has also been addressed with regard to the origin and distribution of information. This study also considers the effect of information asymmetry and market constraints by considering the cash holding to transmit firm information

This study examines the ability of contracts as one of the supply chain coordination mechanisms under competitive conditions. In this study, a two-tier supply chain model with two manufacturers and two retailers is considered to develop a competitive structure when demands are uncertain. The supply chain demand is random and depends on the price of the products. Moreover, the products manufactured by market manufacturers are replaceable. Therefore, the main competitive factor is the order decisions, and due to the nature of the demand, deciding on pricing and ordering is necessary. Each retailer is faced with the issue of determining the prices of goods from two manufacturers, which consequently forms a competitive ground between retailers. Therefore, the two-tiered supply chain model is based on the contract price and is optimized, followed by coordinated analysis. The result of the study shows that to maintain the structure of the supply chain, the manufacturer can increase its wholesale price to the extent that the retailer has zero profit. The lowest price of wholesalers is equal to the cost of production, and the wholesale price can be increased to the point where the retailer's profit is zero.