The recent mania of Reddit darling GameStop raises questions about social media’s impact on the behaviours of institutional investors such as mutual funds. We examine whether and why mutual funds hold “sentimental” stocks that are heavily mentioned or with bullish views on social media....

Social media activities are a proxy for non-fundamental forces that contribute to ETF premium. Greater social media coverage of an active ETF's holdings predicts a greater ETF premium on the next trading day. Active-ETF managers are more likely to sell underlying stocks which experience more...