本文以韓國市場為研究對象，探討在大型企業與中小企業差距顯著的市場環境下，同儕效果是否存在並對企業資本結構決策造成影響。本文以 2020 年至 2024 年間韓國 KOSPI 上市之非金融與非公用事業公司為樣本，並使用同儕公司之特質性股權報酬衝擊作為主要解釋變數，以辨識同儕效果並降低反映問題所造成之內生性疑慮。
實證結果顯示，同儕公司平均股權報酬衝擊與市場槓桿、帳面槓桿及市場槓桿變動皆呈正向關係，表示韓國企業會依據同儕公司所釋放之財務訊號調整其資本結構，且主要透過債務發行而非股權發行回應同儕訊號。此外，在大型企業主導程度較高之產業中，同儕效果更為明顯。本研究顯示，儘管是在企業差距顯著的市場，其資本結構決策仍會受到同儕公司行為與產業結構影響。

This study uses the South Korean market as its empirical setting to examine whether peer effects exist and influence corporate capital structure decisions in a market environment characterized by substantial disparities between large enterprises and small and medium-sized firms. Using nonfinancial and nonutility firms listed on the KOSPI from 2020 to 2024 as the sample, this study employs peer firms’ idiosyncratic equity return shocks as the main explanatory variable to identify peer effects and mitigate endogeneity concerns arising from the reflection problem.
The empirical results show that peer firm average equity shocks are positively associated with market leverage, book leverage, and changes in market leverage. These findings indicate that Korean firms adjust their capital structures in response to financial signals released by their peer firms, primarily through debt issuance rather than equity issuance. In addition, peer effects are more pronounced in industries dominated by large firms. Overall, this study shows that even in a market characterized by substantial firm disparities, capital structure decisions are still influenced by peer firm behavior and industry structure.

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