Internet finance investor sentiment and return comovement

Since more and more investors are affected by the Internet finance, this paper focuses on examining whether the systematic trading among investors would lead to stock return comovements beyond the usual risk factors. Internet finance investor sentiment index (IFIS) measures the sentiment related to Internet finance investors' behaviors, which is found to be a systematic factor of stock market returns. To clarify the influence mechanism of IFIS, two groups of portfolios are constructed. First, stocks are sorted into three portfolios according to their degrees of relevance to Internet financial products. IFIS has more significant impact on stocks of firms closely linked to Internet financial products. Second, the role of IFIS on return comovements is further examined using size portfolios. Interestingly, IFIS has significant incremental explanatory power, beyond Fama and French (2015) five factors, on return comovements for stocks with larger market capitalization. This phenomenon is contradictory to the findings by using existing stock investor sentiment in the literature. Our findings have strong implications for research on Internet finance and stock return comovements.