本研究探討台灣上市公司股權成本與企業社會責任二者之間的關聯性。我們以兩種不同的樣本來研究企業社會責任績效是否對股權成本有直接或干擾解釋能力。本文分別針對兩個樣本作實證研究，樣本一由2007年到2013年天下雜誌企業公民得獎公司所組成，共有234個觀察值;樣本二是由樣本一的觀察公司加上市值與之相近之未得獎公司對照組所組成。由樣本二，本文發現得獎公司相對於未得獎公司具有顯著較低的股權成本。而且，TEJ信用風險指標(又稱TCRI，等級愈高代表為信用風險越高)對於得獎公司的股權成本相對於未得獎公司，具有更高且顯著的正向關係。此結果顯示企業社會責任績效於TCRI等級對於公司股權成本的解釋能力具有干擾效果。最後，樣本一的結果皆不顯著，原因可能是該群組觀測樣本皆為獲獎公司，且各項自變數和因變數的數值不具有足夠的跨公司差異性。

英文延伸摘要 SUMMRY
This study investigates the relationship between corporate’s cost of equity capital and corporate social responsibility for Taiwan listed firms. We employ two sets of data samples to examine whether Taiwan firms' corporate social responsibility performance exerts a direct or mediating explanatory power on their cost of equity capital. Our empirical study is based on two sample sets. The first sample set consists of winners of the Corporate Citizenship Award conferred by Common Wealth Magazine in the 2007 to 2013 period, which totals 234 observations. In addition to the component firms of the first sample set, the second sample set adds to the first sample set one non-awarded firm corresponding to each awarded firm, both having a similar market capitalization in the same industry. Based on the second sample set, we find that those CSR-awarded firms tend to have a lower cost of equity than their non-awarded counterparts. Besides, the TEJ credit risk rating (TCRI, the larger the TCRI measure, the higher possibility for default) tends to have a larger significant, positive effect on the cost of equity. This finding suggests that firms' CSR performance tends to have a mediating effect on the explanatory power of TCRI for the cost of equity of Taiwan listed firms. Finally, we cannot find any statistically significant results for the observations within the first sample set. A possible reason among others might be the insufficient variation on the dependent and independent variables across the sample observations.
Key words: corporate social responsibility, cost of equity, Common Wealth Corporate Citizenship Award, TEJ TCRI

INTRODUCTION
Numerous prior studies suggest that there is a close relationship on corporate social responsibility and value creation for shareholders. Arguably, CSR might increase the cost of operating. However, companies which excel in corporate social responsibility tend to demonstrate a good performance in sustainable business. "The pursuit of maximizing shareholder value" does not mean the only responsibility of business is to increase profits, and the business can not be separate from external exposure to social change. We must respond to the changes in order to achieve business goal.
Our first sample set is composed of Corporate Citizenship award winners conferred by the Common Wealth Magazine during the 2007 to 2013 period. In total, we have 234 observations. To form the second sample set, we add to the first sample set one non-awarded firm corresponding to each awarded firm, both having a similar market capitalization in the same industry. Based on the Fama-French three-factor model, we estimate firms' annualized cost of equity, r_(i,k)^a. The model states that the excess returns of an investment portfolio (including single stocks) can be explained by three factors: the excess return of market portfolio (r_m-r_f), size factor (return premium between the Small and the Big market-cap. portfolios), and the value factor (return premium between the High and Low book value/market value ratio portfolios).
METHODS
In this study, we aim to test the following two hypotheses:
Hypothesis one: For the CSR-awarded companies, the higher their scores of corporate social responsibility, the lower their cost of equity.
Hypothesis two: Those CSR-awarded firms tend to have a lower cost of equity than their non-awarded counterparts
We construct an ordinary least squares regression for both sample sets. To test the first hypothesis, we use the total CSR score provided by Common Wealth as a proxy for a firm's CSR performance in the regression for all CSR awarded firms. To test the second hypothesis, we employ a dummy variable which equals 1 for a CSR-awarded firm and 0 for the firm's non-awarded counterpart with similar market value in the same industry.
RESULTS AND DISCUSSION
Summarizing the above findings, out empirical results show that that, although we have no evidence to support hypothesis one, we find that those CSR-awarded firms do have a statistically significantly lower cost of equity than their non-awarded counterparts. Besides, the TEJ credit risk rating, TCRI, tends to have a significantly larger positive effect on the cost of equity for CSR awarded firms than their non-awarded counterparts. We also find that winning a CSR award in the current year, year t-1 or year t-2 will all show a moderating effect on the explanatory power of TCRI for firms' cost of equity. Stated otherwise, a same unit of credit improvement will reduce the cost of equity for a CSR-awarded firm to an extent larger than its non-awarded competitor in the same industry. To the contrary, a same unit of credit deterioration will make a CSR-awarded firm incur a larger increase in its cost of equity than its non-awarded firm. The results above are robust to the industry effect since we have coupled each CSR-awarded firm with its corresponding counterpart with a similar market value in the same industry for the second sample set.
CONCLUSION
The empirical results of this study demonstrate that firms that were rewarded with a third-party certification on corporate social responsibility can significantly reduce the cost of equity capital. The study finds that the explanatory power of firms’ credit ratings for their cost of equity will be magnified if they were once the Common Wealth CSR-award winners. That is, whether a firm’s CSR performance is accredited by a third party in Taiwan exerts a moderating effect on the explanatory power of the firm’s credit rating for its cost of equity.

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