本文主要研究日本央行實施緊縮性貨幣政策時，日本銀行業貸款組合變動與對實質經濟影響之關係，透過比較貨幣性衝擊、單純產出衰退及總和需求衰退對於銀行貸款組合的影響，以分析銀行在貨幣政策所發揮的功能。經VAR模型實證結果顯示，日本國內貨幣緊縮會使短期實質產出衰退、價格上升；銀行對於家計部門消費信用以及購屋貸款的放款減少、對企業的放款則增加。進一步檢驗不同規模企業貸款發現，銀行對大型企業的放款較為寬鬆，而對於中小企業的放款增幅較不明顯。另一方面，考慮信用標準擴散指數的VAR模型分析發現，日本國內的貨幣緊縮政策使銀行對於家計單位信用標準趨於嚴格的程度最大，再來依序為中型企業、小型企業及大型企業。這些實證結果支持銀行信用管道的存在，也說明銀行在貨幣傳遞機制中扮演重要的角色。 / The paper mainly studies the relationship between the change of Japanese bank loan portfolios and its substantial effect on economy during implementation of monetary tightening policy by Japan authority. Through comparison of monetary impacts, as well as the effects of the downturns in both output and real demand on bank loan portfolios, with the downturns are generated in a way that they produce the same dynamic real output and final demand path as that from a monetary downturn. The empirical results of VAR model reveal that the domestic monetary tightening in Japan would cause decrease in short-term real output and price level rise. General banks offer less consumption credits and house loans for households, but turn to increase loans for enterprises. When further examining the loans for enterprises of different scales, the paper finds that the banks take a looser attitude in offering loans to large-scale enterprises than to small and medium enterprises (SMEs), whose loans seem to have insignificant increase. On the other hand, after analysis of VAR model that considers the credit standard diffusion index, it is found that because of the domestic monetary tightening policy of Japan, the banks’ practices in their offer of credits appear to be strictest to households, and then less strict to SMEs and large enterprises. These facts prove the existence of credit channels of banks, and show the important roles that banks take in monetary transmission mechanism.

【第一篇論文中文摘要】 集中度風險於結構式商品的量化與分析：以房屋抵押貸款證券為例 "Martin and Wilde (2002)與Gordy (2003)" 針對巴塞爾協定(Basel Accords)中金融機構之投資組合所內藴之集中度風險提出了相對應的微粒化調整(Granularity Adjustment)風險量化準則，然而該模型僅止於單因子架構下探究單一信用標的集中度風險之量化。本文將其架構延用至結構式商品中，允許債權群組內之信用標的具不同區域別，我們採用Hull and White(2010)之跨池違約相關性描述，並結合Pykhtin (2004)中延拓單因子聯繫模型至多因子之方式，進而求取債權群組之單一資產集中度(Name Concentration)與區域類別集中度(Sector Concentration)風險的量化。本文以房屋抵押貸款證券(Mortgage Backed Securities, MBSs)為例，於集中度風險的考量下，藉由檢視不同風險情境下分券之損失起賠點，重新評估房屋抵押貸款證券AAA投資級分券信用評級之合理性。研究結果顯示，AAA評等之分券高度曝險於系統性風險，且於高風險情境下，標的房貸之區域集中現象擴大了違約相關性對債權群組損失分配的影響，致使AAA分券之損失起賠點得以超過其實際擔保額度(subordination)範圍。 【第二篇論文中文摘要】 美國銀行放款多角化對其報酬與風險之影響：相關性與傳染的觀點 本文目的在於分析銀行放款的多角化行為對其報酬與風險之影響。研究發現納入銀行放款投資組合相關性之考量，亦即標的資產之相關性結構以及資產間因契約關係所隱含跨投資組合之傳染途徑，將降低多角化之成效。文中透過因子模型(factor model)建構資產之報酬，同時決定其相關性結構，其中將資產間殘差項相關性作為傳染指標，進一步分析投資組合內標的資產間的平均相關係數、傳染與多角化程度間的關聯性。我們以美國銀行作為研究樣本，分別以赫芬達-赫希曼指數估算投資組合權重分配之集中度、使用組合內標的產業股票報酬資訊來計算投資組合內相關程度，接著利用標的產業與投資組合外產業間的殘差相關性來捕捉產業傳染效果，將此三項指標作為衡量多角化指標，分析其在1987年至2014年間聯貸投資組合多角化情形並試圖分析放款多角化對銀行績效之影響。透過契約關係的界定進而探討顧客傳染如何影響銀行績效。 研究發現於市場處於平穩期間(tranquil period)，所有多角化指標銀行放款均呈現放款多角化程度越高越有助於提高銀行的報酬並降低其風險。然而於危機期間(turmoil period)，銀行應將放款權重集中於部分產業、建構相關性較低之組合或選擇較低之傳染效果之產業作為放款的對象，用以提高銀行績效。隱含在危機期間銀行應該選擇適度之多角化策略，若僅以赫芬達-赫希曼指數作為多角化之衡量將顯示危機期間越集中越有助於銀行的表現，此舉將造成解釋上的偏誤。說明於投資組合多角化的衡量上，不該忽略由相關性結構所引發之集中度風險。 / 【Essay I】 Quantification and Analysis of Concentration Risk in Structured Products: the Case of Mortgage Backed Securities Granularity adjustments, introduced by Martin and While (2002) and Gordy (2003), allow one to quantify the concentration exposures of credit portfolios due to imperfect diversification. However, they focus solely on name concentrations under an Asymptotic Single Risk Factor (ASRF) framework. In this study, by adapting the multi-pool correlation structure of Hull and White (2010) under the multi-factor setting of Pykhtin (2004), we derive quantitative measures of name and sector concentration that facilitate subsequent analysis of the risk profiles embedded in Mortgage Backed Securities (MBSs). Under different stress scenarios, we examine the impacts of concentration exposures on the internal credit enhancements, in particular, the AAA tranche attachment points. We show that, under severe market conditions, the presence of sector concentrations in the underlying mortgage pools can further amplify the effects of default correlation on the portfolio loss distributions. As a direct consequence, the predetermined subordination level determined by the assignment of tranche attachment points can be exceeded. 【Essay II】 How Loan Portfolio Diversification Affects U.S. Banks’ Return and Risk: Correlation and Contagion Perspectives. In this paper we investigate how loan portfolio diversification affects the banks’ return and risk. We argue that, the dependence structure of bank loan portfolios, namely, the correlation structure among loan assets and the presence of contagion channels due to contractual relationships across the border of portfolio, contributes to the costs of diversification. Under the factor model framework, we derive a theoretical model to depict the asset returns and their dependence structure. Based on data of US bank loans collected from 1987-2014, our empirical study employs HHI, intra-portfolio correlation, and contagion as proxies for diversification to examine how loan portfolio diversification affects the banks’ profitability and riskiness. In addition, contractual relationships are identified and we investigate how customer contagion affects the bank’s performance. We find that all diversification measures exhibit a positive effect on the performance of U.S. banks during tranquil periods. However, for turmoil periods, banks with loan portfolios of more concentrated weight distributions, lower intra-portfolio correlation, or lower consumer contagion effects would have improved returns and reduced risk. In other words, during crisis, banks should choose an appropriate concentration strategy rather than focus on selected industries as determined solely by the HHI.

Vykdydami savo veiklą bankai susiduria su įvairia rizika, susijusia su lūkesčiais, kad gaunama grąža kompensuos prisiimtą riziką. Bankų veiklos rizikingumą sustiprina ne tik vidinės bankų valdymo klaidos, bet taip pat ekonomikos svyravimai arba verslo ciklai. Ekonomikos augimo laikotarpiu bankai optimistiškai vertina skolininkų ateities perspektyvas ir todėl vykdo liberalią kreditų teikimo politiką. Prasidėjus ekonomikos kritimui, sulėtėjus pinigų srautams, bankų rizikingumas išauga, tai reikalauja didesnių atidėjinių, rezervų ir aukštesnio kapitalo lygio. Problemos aktualumą patvirtina ir paskutinė finansų krizė, kuri yra didžiausia nuo Didžiosios depresijos laikų. Finansų sektoriuje kilusi krizė atsiliepė „tikrajai“ ekonomikai ir sukėlė ekonominiams sunkmečiams būdingus padarinius. Todėl yra ieškoma būdų kaip tinkamai vertinant bankų riziką, laiku užkirsti kelią finansinėms krizėms, o kartu išvengti bereikalingų suvaržymų, stabdančių finansų sektoriaus ir viso ūkio plėtrą. Dėl visų minėtų priežasčių bankų rizikos problemos pastaruoju metu susilaukia daug mokslinės visuomenės, bankų priežiūros ir pačių bankų dėmesio. Darbo objektas – pasirinktų, Lietuvoje veikiančių, komercinių bankų riziką atspindintys rodikliai ir jų ryšys su verslo ciklu. Darbo tikslas – ištirti verslo ciklo poveikį bankų rizikai. Darbo tikslui pasiekti, darbe numatoma išspręsti šiuos uždavinius: • Išskirti bankų rizikos šaltinius; • Išanalizuoti kaip bankų rizika pasikeičia, kintant ekonominėms sąlygoms... [toliau žr. visą tekstą] / Banks in the course of their work are confronted with various risks. That’s risks are associated with the expectation, that the return will compensate the risk assumed by bank. Risk in banking activities not only strengthens the internal management of a bank error, but also economic fluctuations or business cycles. In economic growth times, banks are optimistic about the future prospects of the borrowers and therefore banks acts a liberal supply of credit policies, reducing lending standards. When economy stat’s to fall, the cash flow of money will slow, bank risk profile increases, it requires larger provisions, reserves and a higher level of capital. The work issues confirms the relevance of the last financial crisis, which is the largest since the Great Depression. The financial sector crisis effected "the real" economy and financial crisis caused the specific effects of economic recessions. So it is looking for ways of properly assessing the risk of bank, and to prevent financial crises in time, to avoid unnecessary constraints hindering the financial sector and the economy development. For all these reasons, the banks' risk problems recently attracts many scientific societies, banking supervision, and most banks focus of attention. The object of work - the selection, the commercial banks, operating in Lithuania, risk-reflective indicators and indicators link to the business cycle. The aim of work - to explore the business cycle effects of bank risk. To achieve the aim of... [to full text]

El objetivo de este estudio es analizar el impacto de la diversificación sobre el rendimiento y el riesgo. Se emplea un panel de datos de frecuencia mensual para el periodo 2010-2019 y se utiliza el estimador de MGM por la naturaleza dinámica del modelo. Los resultados muestran que la diversificación de la cartera de préstamos no tiene efecto en el rendimiento del sistema bancario, sin embargo, se observa que los bancos con mayores riesgos pueden aumentar sus rendimientos si aumentan su nivel de concentración por sector económico y departamento. El efecto en el riesgo dependerá del tipo de concentración, un mayor nivel de concentración de préstamos por sector y departamento disminuirá el riesgo crediticio; pero una mayor concentración de préstamos por tipo de crédito aumentará el nivel de riesgo. Además, se observó que no hay ningún efecto sobre el riesgo ni el rendimiento dependiendo de si el banco es de capitales domésticos o extranjeros. Los hallazgos son importantes para los bancos al elegir su estrategia crediticia y clave para las autoridades regulatorias. / The objective of this study is to analyze the impact of diversification on performance and risk. A monthly frequency data panel is used for the period 2010-2019 and the MGM estimator is used because of the dynamic nature of the model. The results show that loan portfolio diversification does not affect the performance of the banking system, however, it is observed that banks with higher risks can increase their returns by increasing their level of concentration by economic sector and department. The effect on risk will depend on the type of concentration, a higher level of loan concentration by sector and department will decrease credit risk; but a higher concentration of loans by type of credit will increase the level of risk. Besides, it was noted that there is no effect on risk or return depending on whether the bank is domestic or foreign-owned. The findings are important for banks when choosing their credit strategy and key for regulatory authorities. / Trabajo de investigación