過去文獻僅探討融資與投資策略、多角化與融資策略及多角化與投資策略之間的關係，並未深入討論多角化、融資與投資策略三者之間的關聯性。根據Myers' (1977)的代理問題指出，股東與債權人之間的代理問題，使融資與投資之間存在著負向關係；舉債能力理論預期從事多角化能夠增加公司的舉債能力，因此多角化與融資有著正向關係；投資不足理論預期多角化公司藉由創造一個很大的內部資本市場來降低投資不足的問題，因此多角化與投資有著正向關係。然而，當多角化、融資與投資策略三者同時考量時，若公司從事多角化能夠增加公司的舉債能力，那麼多角化策略是否可減緩投資不足的問題是令人質疑的。一方面，多角化增加公司的舉債能力，但過度舉債增加投資不足的可能性，因為槓桿限制公司從事投資策略的能力，另一方面，多角化能夠平穩公司的現金流量，反而降低投資不足的可能性。因此，本研究旨在探討多角化、融資與投資策略三者之間的關聯性。
本篇論文研究對象為台灣上市公司，研究期間為1995至2007年。實證結果發現公司從事多角化增加其舉債能力，卻無法同時降低公司投資不足的問題。此結果與舉債能力理論一致，若公司從事多角化的程度越高且進行投資計畫，公司的舉債會跟著增加。但與投資不足理論不一致，可能來自於Myers’(1977) 的代理問題，認為股東與債權人之間的代理問題導致投資不足的問題產生。

Prior literature has actively investigated the relationships between financing and investment strategies, diversification and financing strategies, or diversification and investment strategies in isolation. The argument based on agency problem between shareholders and debt holders suggests a negative relationship between leverage and investment; the debt capacity theory suggests that firms diversify to increase their debt capacity; and the underinvestment theory proposes that diversified firms may reduce the underinvestment problem. However, as diversification, financing, and investment decisions considered simultaneously, we argue that increasing leverage due to diversification may not mitigate the underinvestment problem.
This paper consists of Taiwan listed companies, covering fiscal years 1995-2007. Our results suggest that although firms may diversify to increase their debt capacity, diversification may not increase their capital expenditures simultaneously. We also find evidence to support the debt capacity theory that if firms engage in higher degree of diversification and then undertake investment projects, their leverage will increase. Because diversified firms have the ability to issue more debt externally to pursue their investment due to their greater debt capacity. However, the increase of debt capacity due to diversification may not reduce the underinvestment problem. The finding is not consistent with the underinvestment theory, but may result from Myers’ (1977) agency problem which leads to an underinvestment problem. Overall, our empirical results suggest that appropriate diversification strategy will help firms undertake their financing and investment decisions more successfully. The findings in this study may also have shed light on the paradoxes of prior literatures on diversification.

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