Evaluating the Relative Effectiveness of Deposit Insurance and Capital Requirements in Restraining Risk Taking in Banking

評估存款保險與資本準備對銀行涉險行為抑制之相對有效性

There are two regulatory polices as major financial system safety nets, deposit insurance and capital requirements. By using financial intermediary model, we evaluate relative effectiveness of these regulatory policies in restraining bank’s risk taking. For each of them, there are two types of regulatory policy, flat and risk-based. In our study, we confirm risk-based regulatory policies are better than flat type one. Secondly, in evaluating relative effectiveness of restraining risk taking, there are two major forces working together, marginal benefit and marginal cost in taking risk. When marginal benefit in risk taking is greater than marginal cost in taking risk, risk-based deposit insurance premium is more effective than risk-based capital requirements in containing risk-taking incentives; otherwise, risk-based capital requirement is more effective. We conclude that proper regulatory policy combination should take these marginal benefits and costs of bank risk taking into safety net design consideration in order to prevent financial system fragility. 在金融體系安全網設計上，有兩種主要制度規範：存款保險與資本適足率。本文運用金融中介模型以評估這種兩種制度規範在抑制銀行涉險行為的相對有效性。對於這兩種制度規範各有兩種型態：固定與風險調整(risk-based)。在本研究中，我們除了確認風險調整型態的規範制度相對有效外，同時也發覺有兩股作用交互影響進而決定了此相對有效性：銀行涉險行為的邊際利益與邊際成本，前者代表涉險行為對銀行所產生預期資金(存款)成本降低，後者代表涉險行為所帶來對銀行集資成本增加；當銀行涉險行為的邊際利益較大時，風險調整型存款保險費率制度在抑制涉險行為上將會相對有效；反之，當銀行涉險行為的邊際成本較大時，風險調整型資本適足性政策將會相對有效。就此，我們認為在金融體系安全網設計上，就政策意涵應該將這兩種作用同時考量以健全金融體系並排除銀行涉險誘因。