本文旨在探討不對稱資訊下，銀行如何設計包裹形式之最適信貸契約以篩選風險性投資廠商之類型，進行信用配給並提高資金配置效率。本文藉由修改Bester (1985) 模型基本設定之錯誤，將銀行為風險中立者、廠商為風險規避者之設定，修改成銀行為風險規避者、廠商為風險中立者，將模型重新進行建構與論述。除了資金供需均衡，本文更考慮資金供不應求的情況，分析可能出現的角點解。本文除了更加一般化Bester (1985) 之結論，並且進一步完成其所未能達成的工作：證明在合理條件下，若高風險廠商之抵押金不高於低風險廠商之抵押金，則前者之還款金額必然高於後者之還款金額。

The thesis studies how bank may design a set of credit contracts, under asymmetric information, to screen and ratio loanable funds among the firms that each of which owns a different kind of risky project to invest. By correcting Bester’s (1985) modeling error which assumes a risk-neutral bank and risk-averse firms but lead to certain conflict results, the study rebuilds the model with a risk-averse bank and risk-neutral firms in contrast and arrives at more rigorous and general conclusions. Besides the credit equilibrium situation, the thesis explores possible corner solutions resulting from an excess demand for credit and further clarify the relationship between repayment and collateral for different kinds of risky project, a result which Bester (1985) failed to demonstrate. It shows that, under reasonable conditions, the repayment required for a high-risk project is always higher than a low-risk project whenever the collateral required for the former is not higher than the latter.

目錄
論文審定書.................................................................. i
謝辭............................................................................ ii
中文摘要..................................................................... iii
英文摘要..................................................................... iv
第1章 緒論................................................................. 1
第2章 Bester (1987) 模型推論之可能錯誤
2.1 Bester (1987) 模型之基本設定................................. 3
2.2 Bester (1987) 模型之可能錯誤................................ 6
第3章 最適抵押貸款契約角點解的可能情況
3.1 Bester (1987) 基本假設與模型之修訂..................... 11
3.2 最適契約的可能情況： Xi 之角點解的探討
3.2.1 條件一成立時之情況分析................................... 16
3.2.2 條件二成立時之情況分析.................................... 23
3.2.3 條件三成立時之情況分析................................... 26
3.2.4 小結................................................................... 35
3.3 抵押金上限與最適契約的關係............................ 37
3.4 最適契約條件之抵押金與還款金額的關係............. 40
第4章 結論................................................................ 42
數學附錄..................................................................... 44
參考文獻................................................................... 47

Bester, Helmut (1985), "Screening vs. Rationing in Credit Markets with Imperfect Information, " American Economic Review, 75, 850-855.
Bester, Helmut (1987), "The Role of Collateral in Credit Markets with Imperfect Information, " European Economic Review, 31, 887-899.
Bolton, Patrick and Mathias Dewatripont (2005), Contract Theory, MIT Press: Cambridge, Massachusetts.
Stiglitz, Joseph E. and Andrew Weiss (1981), "Credit Rationing in Markets with Imperfect Information, " American Economic Review, 71, 393-410.
Wette, Hildegard C. (1983), "Collateral in Credit Rationing in Markets with Imperfect Information: Note, " American Economic Review, 73, 442-445.