在2008 年金融海嘯中我觀察到如雷曼兄弟等"Too big to failed"的大型金融機構即使 在危機發生時仍然有恃無恐,繼續進行一些高槓桿的投資,因為他們相信即使倒閉政 府也會因為會產生很大的系統性風險而出手救助。本文旨在探討如何設計一套事後的 救助政策來影響"Too big to failed"的大型金融機構事前的投資。;In the 2008 financial crisis, I observe those so-called“too big to failed"financial institutions such as lehman brothers still engage in highly risky investments after the crisis happened. They believe that if they go bankrupt the government will bail them out no matter what. And they can still engage in those high leverage investment because even if the investment failed, the government will still save them by letting taxpayers bear the consequences. In this paper, we discuss how ex-ante “too big to failed"problems and the ex-post dishonest of the bankruptcy will affect social welfare. We are on the side of the government to design the bailout policy trying to minimize the inefficiency caused by asymmetric information.