دکتر حسین عسکری راد

In this study, systemic risk index (β) was measured and decomposed by using the extreme value theory in the banks listed in Tehran Stock Exchange (TSE) during 2013-2021. This index was divided into two dimensions: total bank risk (tail risk) and link of the bank to the system during the financial crisis (system linkage). Using autoregressive distributed lag (ARDL) regression, the relationships between systemic risk and its dimensions with the characteristics of the banks and the relationships between their economic value-added (EVA) and various financial risks, including systemic risk, were calculated. According to the results, Post-Bank, Tejarat, and Saderat banks imposed the highest systemic risks and Karafarin and Eghtesad-e Novin banks imposed the lowest systemic risks, respectively. The results showed that with increasing the bank size, the systemic and tail risks that are specific to each bank decreased and the systemic linkage increased. There was a positive and significant relationship between the EVAs of the banks and their ratios of regulatory capital to credit risk-weighted assets. Also, there was a negative and significant relationship between the EVAs of the banks and their ratios of core capital to operational risk-weighted assets, net sustainable financial resources, and interest rate risk variables.

In this paper, the effect of banks network topology on banks systemic risk in Tehran Stock Exchange have been investigated by using banks daily stock return from 2013 to 2021. First, systemic risk index have been measured and decomposed by using EVT approach and then this index divided into two dimensions, bank tail risk and systemic linkage. Then the network between banks listed in the banking industry of Tehran Stock Exchange have been created based on dynamic conditional correlations (DCC) by using the spanning minimum tree (MST) approach and the banks network topology have been measured. Finally, the relationship between banks systemic risk and its dimensions with banks network topology have been investigated by using regression of panel data. According to the results, Post-Bank, Tejarat and Saderat banks have the highest and Karafarin and Eghtesad-Novin banks have the lowest systemic risk, respectively. Also, the regression results showed that there is a positive and significant relationship between the variables of node strength, betweenness centrality and size with the banks systemic risk and a negative and significant relationship between the variables of node degree and liquidity with banks systemic risk.

 We empirically tested, in Tehran Stock Exchange (TSE), the validity of the Carhart (1997) four-factor model by adding the price momentum factor as the fourth explanatory variable into the Fama-French three-factor model. The results imply that growth portfolio in comparison to value portfolio and also winner portfolio to loser portfolio have higher returns. However, with regard to Size factor no clear trend was observed. The average adjusted R2 across eight portfolios for single factor CAPM model, Fama-French three-factor model and Carhart four-factor model has been respectively 0.26, 0.50, and 0.56 showing a significant improvement in the four-factor model by adding the momentum factor to Fama-French model. Robustness of the Carhart four-factor model is also checked for two effects: up and down market conditions and seasonal behavior.