EU trade strategies which include multilateralism, bilateralism/inter-regionalism, unilateralism, and protectionism have displayed different trends in different time periods. Regarding the determinants of EU trade strategies, while institutionalist approach points to the roles played by core EU institutions, pluralist approach draws attention to the influence of domestic interest groups. Systemic approach, on the other hand, underlines the impact of external constraints or opportunities. Nevertheless, neither of these approaches can provide a complete explanation as each of them focuses on the impact of one factor. The aim of this thesis is to investigate the changing dynamics and determinants of EU trade strategies by developing a more interactionist approach. For this purpose, firstly, main arguments of the previous approaches utilized in the analysis of EU&rsquo / s external trade policy are critically reviewed. Later, all the major factors proposed by previous approaches are brought together in an interactionist manner in order to demonstrate that a direction of influence exists among these factors and they each play a distinct role in the determination of EU trade strategies. Secondly, reasons behind different trends displayed by EU trade strategies throughout history are investigated by utilizing the interactionist model for three major periods: 1958-1995 / 1995-2000 / 2000-present. The analysis reveals that in all three periods, external factors always drive the EU to reconsider its trade strategies while their specific content is rather shaped by domestic dynamics.

本文主要研究外資、投信及自營商這三大法人是否有「處分效果」及「過度自信」行為上的偏誤，並想要進一步探討投資人是否可以透過觀察三大法人在不同景氣狀態下的異常行為建立投資組合以獲得顯著的超額報酬，故利用Weber and Camerer（1998）所提的處分係數（The disposition coefficient）來表示處分效果及黃坤興（2006）提出的修正過度自信係數（The overconfidence coefficient）代表過度自信現象，並採用二情境轉換模型，以馬可夫鏈描述情境轉換行為，觀察三大法人在2005年至2013年台灣股票市場上的行為。 研究結果發現在不同的景氣狀態下三大法人會有不同的異常行為產生，在景氣繁榮期外資有處分效果而無過度自信，投信則無異常行為，而自營商沒有處分效果而有過度自信傾向；在景氣低迷時期外資有處分效果而無過度自信現象，投信沒有處分效果而有過度自信，自營商則是同時有處分效果與過度自信，而投資人可以在三大法人有異常行為時，利用放空高係數資產及買入低係數資產獲取正報酬。