本研究乃結合管理變數中，與成長有關的競爭力變數及與風險有關的多角化變數，以股價評價模式來推論這些變數對公司價值的影響；並在公司治理變數中，以管理當局代理問題有關之經理人持股及與股東代理問題有關之股權集中度，來探討這些變數是否會增強或削弱管理變數對公司價值的影響；此外在研究方法上， Petersen （2009）指出不少 panel data模型的殘差處理有相當程度的偏誤，是以本文採取Petersen（2009）的修正模型來作為本文的實證模型，並有以下重要的研究發現。首先，市場佔有率對公司價值的影響並不正面，此可能源自削價競爭所致，但是當股權集中度提高時，將有助於公司削弱此不利因素；再者，多角化亦不利於公司價值的提升，但是經理人持股比率較高的多角化公司，將會降低此不利因素對公司價值的衝擊；換言之，雖然有些多角化與競爭力的代理變數似乎會造成公司治理上的問題，並進而降低公司價值，但公司治理良好的產業多角化企業或高市佔率的企業，則反而有降低風險與提高成長之效。

This research is to investigate whether corporate governance variables such as managers’ shareholdings and high concentration of directors’ shareholdings will enhance or weaken competitive and diversified variables to the effect of firm values through the combining management variables competitiveness deemed as growth variable and diversification variables deemed as risk variable through the stock pricing model. In addition, Petersen (2009) point out the residual of several panel data models exist considerable degree of bias, so we adopt the revised models raised by Petersen (2009) as the empirical models for this research and disclose the following important findings. First of all, market shares of enterprises are negative for firm value due to the probable results of enterprises’ cutting price strategies, but high concentration of directors’ shareholdings will weaken this negative effects. Next, diversifications are unfavorable for raising firm values, but higher managers’ shareholdings would reduce the negative impact to firm values. In the other word, some proxy variable for competitiveness or diversification seem to cause the problem of corporate governance, but industry diversification or high market share enterprises with sound corporate governance might have the effect of reducing risks and raising growth for enterprises.