Do internet stock message boards influence trading? Evidence from heavily discussed stocks with no fundamental news

Authors Sabherwal, Sarkar, Zhang
Journal Journal of Business Finance & Accounting
Year 2012
Type Published Paper
Abstract This study extends the literature on the information content of stock message boards. To better understand the effect of online postings on trading activities and reduce the error due to stocks with small message board followings, we examine stocks with no fundamental news and high message posting activity. Such stocks tend to be of small firms with weak financials. For those stocks, we find a two-day pump followed by a two-day dump manipulation pattern among online traders, which suggests that an online stock message board can be used as a herding device to temporarily drive up stock prices. We also find that online traders' credit-weighted sentiment index, but not the number of postings, is positively associated with contemporaneous return and negatively predicts the return next day and two days later. Also, absolute sentiment is negatively related with contemporaneous and next day's intraday volatility and positively related with the proportion of volume in small-sized trades. We conclude that message board sentiment is an important predictor of trading-related activities.
Keywords Internet stock message board, online trading, investor sentiment, noise trader, naive bayesian, text classifier
URL https://onlinelibrary.wiley.com/doi/full/10.1111/j.1468-5957.2011.02258.x
Tags Archival Empirical  |   Asset Pricing, Trading Volume and Market Efficiency  |   Financing- and Investment Decisions (Individual)  |   Media and Textual Analysis