This dissertation presents three different closely related topics on the value of eco-friendliness in the financial market. The first essay attempts to estimate hedonic stock price model to find a contemporaneous relationship between stock return and firms’ environmental performance and recover the value of investor’s willingness to pay of eco-friendliness. This study follows stock and environmental performances of the 500 largest US firms from 2009 to 2012. The firms’ environmental data come from the Newsweek Green Ranking, both aggregate measures: green ranking (GR) and green score (GS), and disaggregate measures: environmental impact score (EIS), green policy and performance score (GPS), reputation survey score (RSS), and environmental disclosure score (EDS). The results show a non-linear relationship between environmental variables and stock return, i.e. upside down bowl shape or increasing in decreasing rate. That means for low green ranking firms the marginal effect is positive while for high green ranking firms the marginal effect is negative. The investor’s willingness to pay (WTP) for a greener stock for firms in the lowest 25 green ranking, on average, is 0.0096% higher stock price. The second essays attempt to determine if a firm’s environmental performance affects future systematic risk. Systematic risk measures an individual stock’s volatility relative to the market price. This study also uses the Newsweek Green Ranking’s environmental variables. The results show significant evidence of a non-linear relationship between green variables and systematic (market) risk, but the shape is not unanimous for all environmental variables. The shape of the relationship for green ranking (GR), for example, is U-shape. This means that for the firms in the bottom rank, improving rank will lower systematic (market) risk, and for the firms in the top rank improving rank will increase systematic (market) risk. On average the marginal effect for the firms in the bottom and top 25 firms are -0.2% and 0.09% respectively. The third essay is the effect of a firm’s environmental performances on a firm’s idiosyncratic risk. Idiosyncratic risk measures an individual stock’s volatility independent from the market price. This study also uses the Newsweek Green Ranking’s environmental variables. The results show significant non-linear relationships between environmental variables and idiosyncratic risk, even though there is no unanimous shape among the environmental variables. In the case of green ranking, for example, it has U-shape; for the firms in the bottom rank, improving green ranking will lower idiosyncratic risk and for firm in the top green ranking, improving green ranking will increase idiosyncratic risk. On average the marginal effect for firm in bottom and top 25 firms are -0.4% and 0.2% respectively.