We analyze a model of informed trading where an activist shareholder accumulates shares in an anonymous market and then expends costly effort to increase the firm value. We find that equilibrium prices are affected by the position accumulated by the activist, because the level of effort...

Using rumor verification data from investor interactive platforms, we investigate the effect of stock market rumors on price efficiency. We find favorable rumors are positively correlated with stock price synchronicity, while unfavorable rumors are negatively correlated with stock price...