Many researchers (Hall, 1993; Stein, 1988) argue that investors focus excessively on short-term profits and do not value research and development (R&D) investments which create new strategic options for firms. So, firms with significant R&D investments may be undervalued. Many R&D investments are not profitable and hence the valuation of some R&Dintensive stocks is excessively high and leads to value destructive action of the managers (Jensen, 1993, 2005). Further, R&D investments generate more uncertain future benefits than investment in tangible assets (Kothari, Laguerre, and Leone (2002). Current literature documents that, due to limited investor attention, prices do not fully and immediately impound the relevant public information, specifically when such information is less noticeable (e.g., Barber & Odean, 2008; DellaVigna & Pollet, 2009; Fang & Peress, 2009; Hirshleifer, Lim, & Teoh, 2009; Hirshleifer & Teoh, 2003; Hong & Stein, 1999; Hou, Xiong, & Peng, 2009; Huberman & Regev, 2001; Klibanoff, Lamont, and Wizman,1998; Peng & Xiong, 2006; Yuan, 2015). Accordingly, we expect investors to have difficulty processing information that is less tangible and more ambiguous (such as unexpected increases in R&D investments). In other words, it is highly likely that information about the prospects of a firm developing new products, technologies or other innovations is difficult to efficiently impound into the stock pricing process. This is mainly due to the significance of such news upon strategic options and potential disruptions in the industry. Additionally, it is documented that individuals/investors pay less attention to information that is harder to process (Corwin & Coughenour, 2008; Song & Schwarz, 2010). Collectively, these discussions raise the question of whether stock market values of companies reflect the changes in large intangible assets associated with R&D expenditures. Furthermore, there is a dearth of empirical literature that investigates the relations between the changes in R&D investments and stock returns. One of the main reasons behind the limited scope of the literature is that the accounting value of R&D expenditures provides an aggregate value, and hence does not provide clear information about the content of these investments.