The idea of investor sentiment dates back to mid-twentieth when Keynes (1936) proposed that markets are influenced by investors’ Banimal spirits^, causing prices to deviate from fundamentals. This idea is formalized by De Long et al. (1990), who theoretically demonstrated that sentiment changes can lead to noise trading and excessive volatility. Now, the question is no longer whether investor sentiment affects stock market valuation, but how to directly measure investor sentiment and quantify its effects. Extant studies identified two kinds of sentiment measures (Lee et al. 1991; Neal and Wheatley 1998; Brown and Cliff 2004). The first sentiment measures are derived from surveys while the second measures relied on objective variables that correlate with investor sentiment. Both of these two measurements has limitations as they heavily relied on some proxies as mediators to reflect investor sentiment (Schmeling 2009; Carlin et al. 2014). The way to directly measure investor sentiment is still waiting for further exploration. Despite the number of published works on the issue of investor sentiment, several avenues of research remain unexplored. In particular, the empirical question of a relationship between individual sentiment dispersion and stock price valuation remains unresolved. Dispersion in investor sentiment are often mentioned as a factor that could explain the stock volatility but rarely analyzed (De Long and Shleifer 1991; Shiller 2000). Although various proxies of sentiment are utilized in these papers, most of these research ignored the difference of opinions among investors, or the diversity of investor sentiment, which in theory has impact on asset price, risk and returns (Varian 1985; Qian 2014; Miller 1977) and can lead to higher uncertainty and more trading (Carlin et al. 2014). The fact that sentiment diversity is ignored could result from the proxies of measuring investor sentiment. Some of the methods such as survey questionnaire is difficult to generate enough data points to estimate the sentiment dispersion, some of them can only provide one sentiment score for each week or each month, and common sentiment analysis tools only predict the polarity of the sentiment (i.e. only predict positive or negative for each sentence). The high difficulty of sentiment measurement causes big challenges for scholars. This condition leads to a second limitation. Most of extant research only focuses on institutional investor sentiment (Gao and Kling 2008; Verma and Soydemir 2009), and the individual sentiment is commonly measured by proxies such as the survey of expectation (Brown and Cliff 2004; Fisher and Statman 2000) and consumer confidence (Schmeling 2009). This is despite the fact that United States individual investors have been holding around 50% of the stock market in direct stock investments. Therefore, the role of individual sentiment dispersion in theories of financial behavior and the relationship between this factor and stock price valuation are two pieces of white papers.