代理人問題會產生利益衝突，使得資本支出決策與股價報酬有負向相關。
台灣企業其創辦者與親屬都握有可觀的股權，對公司經營有顯著的影響。過去的研究顯示:家族成員財富與公司價值是息息相關的，也常希望把財富留給下一代(Casson 1999)，而非短視近利(Anderson and Reeb 2003, 2004)。因此家族股權能減少代理人問題。
本文以Carhart(1997)所提出的四因子模型為分析方法，以台灣上市股市為對象，研究公司屬性中的“家族股權集中程度”對企業投資支本支出決策成效的影響。將所有股票分成「增加資本支出」股及「減少資本支出」股，再將上述兩組細分為「家族股權集中」股及「家族股權分散」股，研究此兩類股資本支出與股票超額報酬之間的長期關係並探討家族股權在此一關係中扮演的調節變數角色。重要研究結果為：
1.透過因子模型，本研究發現「增加資本支出」、「減少資本支出」兩群組都會導致長期股價負向報酬。因為增加超額資本支出會因代理人問題導致長期股票負報酬。而減少資本支出是因為經理人看壞未來發展而停止資本投資，導致股價下跌，也會使得公司科技、技術落後競爭對手。尤其本研究樣本超過40%為產業變動快速的電子業，更容易受到技術落後的壓力。
2.因子模型顯示對於增加資本支出的類股，家族股權能減輕因代理人問題導致資本支出與股票報酬負相關。証實家族股權能發揮監督效能，減少代理人問題產生。對於刪減資本支出的企業，家族股權無法減低代理人問題。

Agency problem may cause the negative relationship between capital expenditure and stock return. Titman,Wei and Xie (1999) documented this negative relationship in the U.S. by using characteristics model and four factor model. This significant negative relationship occurs when firms with low debt level and high free cash flow. In other words, firms with slack resources tend to overinvestment and harm firm value and stockholders wealth in the future.
Most firms in Taiwan whose family members hold substantial of equity ownership. Family members have substantial incentives to monitor managers and to maximize firm value rather than consume wealth during their lifetime (Casson 1999 ; Anderson and Reeb 2003, 2004). That is family ownership can alleviate agency problem.
This thesis found firms will suffer negative stock return whether they increase or decrease capital expenditure. Agency problem may cause negative stock return after increasing capital expenditure. For firms reducing capital expenditure may lose their long-term competitiveness in a changing business environment. This study reveals family ownership have monitor power and alleviate agency problem for those firms increasing capital expenditure but can’t not alleviate the negative relationship for those reducing capital expenditure.

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