在公司績效的決定因素的研究中，本研究採用Marginal q作為衡量企業投資效率的指標，發現內部人持股比例與公司經營績效間之關係綜合「利益收斂說」以及「掠奪性假說」兩種效果，隨內部人持股比例呈倒U字形先增後減的非線性關係。其他控制變數方面：機構投資人能擔任監督管理者的角色、有效降低代理成本增進公司價值；規模對公司績效大致呈正面影響，惟效果並不顯著；在Tobin's q模型，研發活動支出比例對公司績效有正面的影響；在Marginal q模型，研究發展支出比例對公司績效影響不顯著。本研究亦考量董監質押比例的影響，結果顯示，公司績效僅與董監質押行為負相關與質押比例則無顯著關係。本研究亦採用一個新的衡量內部人持股變數—平均每位董事/監察人持股，該變數亦能精確衡量內部人持股。考量模型內生性的問題後，內部人持股比例與公司績效之關係，並未因此改變。 / We investigate the determinants of the performance of the firm measured by Tobin's q and Marginal q in our study, and find a curvilinear relation between firm value and insider ownership. The traditional measure, Tobin's q, suffers from several drawbacks. Among which the endogeneity is the most serious one which may cause the relationship spurious. As for other controlling variables, we found that institutional investors are able to supervise the management effectively, which implies lower agency cost. The size of the firm is contributive to the value of the firm; however, the influence is not significant. R&D has positive and significant impacts on Tobin's q as we expect. There is less reason to expect a positive relationship between R&D and Marginal q. Indeed, we didn’t find any significant relation in our regression result. We also include the mortgage ratio of the insiders in our study. We conclude that performance is related to whether the insiders mortgage or not. The extent of mortgage doesn’t matter. We construct a new variable –average insider ownership– which could also measure the extent of insider holding well. Considering the possibility of endogeneity, the relation between insider ownership and performance of the firm is still consistent with the result of our study.

La Porta 等人以提高內部人持股可使內、外部股東利益一致，進而降低代理問題的觀點出發，在2002 年發表的實證研究中指出，提高內部人持股有助於提升公司的價值，特別是在對外部投資人保護較差的國家；他們也發現，對投資人保護程度愈好的國家，該國企業的價值也較高。本研究則從提高內部人持股可能產生的代理問題著手，在利弊同時存在之下，以涵蓋範圍更廣、時間更長的樣本，探討在不同的投資人保護環境下，提高內部人持股對公司價值的影響，以及投資人保護程度對於內部人持股集中與分散的公司價值是否也有不同的影響。 本研究發現，在投資人保護較佳的國家，提高內部人持股會傷害公司價值，但在投資人保護較差的國家，提高內部人持股可增加公司價值。另外，公司價值與內部人持股率之間呈現曲線關係，當內部人持股率相對較低時，提高內部人持股對公司價值是弊多於利；當內部人持股水準相對較高時，提高內部人持股則是利多於弊。而投資人保護程度對於內部人持股較分散的公司而言，顯得較為重要。因此，法律層面對投資人的保護程度和內部人持股集中度對於公司價值的影響有顯著的替代效果。 / This paper uses a sample of companies from 34 countries around the world to shed light on the relationships among legal protection of shareholders, ownership structure, and firm value. La Porta et al. (2002) indicate a positive relationship between cash flow, ownership, and firm value, especially in countries with poor investor protection. Besides, they also find evidence of higher valuation of firms in countries with better protection of minority shareholders. However, they don’t consider the effect of higher ownership on the cost of stealing, which may cause the controlling shareholders to expropriate more from minority shareholders. Also, their study covers only large firms with a controlling shareholder by one year data. Their results can be restricted to large firms and a particular year. Therefore, we use more comprehensive time series and cross section data to probe into the subject. Using various specifications of the valuation regressions of Fama and French (1998), we find that higher ownership improves valuation in poor protection countries while higher ownership deteriorates valuation in good protection countries. In addition, stronger legal protection improves firm value, especially the firms with low ownership concentration. That is, there is a substitute effect of legal protection and ownership concentration on firm valuation. Finally, we also testify that dividends are valued more in poor protection countries and firms with low ownership concentration.