本研究探討企業複雜性如何影響債務選擇，特別聚焦於銀行債務與公開債務之間的平衡。利用1998年至2023年間美國上市公司樣本，並採用 Loughran 和 McDonald（2024）提出的文字型企業複雜性指標，結果顯示，企業複雜性越高，對銀行債務的依賴越低，而對公開債務的依賴則越高。而經濟模型證實，企業複雜性會降低內部資本市場的效率，進而提升外部融資需求。因此，企業會依據複雜性所導致的邊際成本變化，在銀行貸款、公開債券與私人債務之間重新分配資金，導致對銀行融資依賴減少，對公開市場融資依賴增加。根據金融仲介理論與融資順位理論，本研究提出兩個主要的作用機制：企業效率的提升以及財務限制的降低。透過替代模型、工具變數與配對式雙重差分等穩健性檢驗，結果一致支持上述推論。研究發現顯示，企業複雜性會重塑銀行與債券持有人在企業資本結構中的角色，並提供新的見解，說明組織複雜性如何影響銀行監督與債券市場之間的互動，以及企業債務結構的最適設計。;This study explores how firm complexity influences debt choice， focusing on the balance between bank and public debt. Using a panel of U.S. public firms (1998–2023) and a text-based complexity index (Loughran and McDonald， 2024)， we find that greater complexity lowers bank debt reliance while increasing public debt. Our economic model confirms that complexity reduces the efficiency of internal capital markets and increases firms’ external financing needs. As a result， firms allocate bank loans， public bonds， and private debt based on complexity-driven marginal costs， leading to less reliance on banks and greater use of public markets. Guided by theories of financial intermediation and the pecking order， we propose that these effects run through two key mechanisms: higher firm efficiency and lower financial constraints. Robustness checks with alternative models， instruments， and matched DID confirm these results， offering insights into how complexity shapes the roles of banks and bondholders in firms’ capital structure. These findings provide new insights into how organizational complexity influences the monitoring role of banks versus bondholders and the optimal design of firms′ debt structures.
