This thesis examines the effect Norway’s Government Pension Fund Global (GPFG) has on the companies it excludes from the portfolio. The data sample consists of 25 companies excluded based on environmental damage and unacceptable greenhouse gas (GHG) emissions. An event study has been conducted to examine whether the exclusion from the fund has a negative impact on the companies’ stock prices. This makes it possible to examine the abnormal returns, and whether they are affected by the exclusion. The main findings and conclusion are that the exclusions do not negatively influence the excluded firms. The influence of exclusions does not result in statistically significant negative abnormal returns, and thus we fail to reject the null hypothesis. These findings are inconsistent with the majority of earlier studies, which found that the exclusion had a statistically significant negative impact on the excluded companies. This may be because of the differences in the data selection, and information leakage, or it might be explained by the fact that there are always willing buyers. One explanation may also be that investors do not regard sustainability as important and essential for their investments