Celebrity endorsement is defined as an agreement between a publicly recognized celebrity and an entity to use the celebrity’s fame to promote a brand or product. Generally, a celebrity is defined as a famous singer, actor, or athlete who frequently appears in public. The celebrity uses his/her public recognition to persuade consumers to purchase a specific product by the endorsement, and the celebrity accepts remunerations from the firm. Celebrity endorsement has been prevalent as an advertising strategy and many advertisers invest enormous amount of money for the celebrity endorsement. Prior research has examined the economic benefits or effectiveness of celebrity endorsement and found that celebrity endorsement attracts attention from consumers and polishes a tarnished brand image, and the celebrity may help advertisements stand out, thus improving their communicative ability. Apart from a general celebrity endorsement advantage, previous studies have found the factors that affect the success or failure of celebrity endorsement. An attractive celebrity can positively influence advertising evaluation, and a celebrity with expertise can increase consumers’ purchase intention through product. In addition, consumers prefer a product endorsed by a highly trustworthy celebrity. Specifically, on the economic worth of celebrity endorsement, most studies have indicated a positive effect. An announcement of a celebrity endorsement contract can bring a positive abnormal benefit to a firm’s stock price. Celebrity endorsement also helps increase the intangible value of a firm, which is the source of competitive edge and sustainable growth. However, despite recent interest in the return on advertising investment, it is not known how and which source factor of the celebrity endorsement can be explained with the firm value. By using text mining and sentiment analysis, the results of this study explain that the sustainable firm value is impacted by various sources of celebrity endorsement. First, the number of words regarding celebrity attractiveness, expertise, and trustworthiness has an impact on the sustainable firm value. Among the three sources, trustworthiness has the biggest impact on the sustainable firm value, which is Tobin’s Q. Second, regarding attractiveness and expertise, increasing proportion of positive words has impact on the firm value. On the other hand, regarding trustworthiness, the number of negative words on occupational issues is important. Third, different celebrity expertise has different impact on the sustainable firm value depending on the degree of job uniqueness and replaceability. Fourth, once the celebrity has lost his/her trustworthiness, the negative impact is hardly recovered as the negative interaction effect between positive impact of celebrity expertise on the sustainable firm value and the loss of trustworthiness is over seven times higher than the positive effects from the expertise. This implies that if an advertiser carefully manages other effects except for the loss of trustworthiness, he/she cannot offset the failure.

• Moon Young Kang(Korea Advanced Institute of Science and Technology, Republic of Korea)
• Yonglim Choi(Korea Advanced Institute of Science and Technology, Republic of Korea)
• Jeonghye Choi(Yonsei University, Republic of Korea)