Optimal Stealth Trading of the Insider and Expected Profit of the Mimicking Trader*

Abstract

AbstractIn this paper we perform theoretical and empirical analyses on the insiders' optimal “stealth” strategy and expected profits from mimicking trading when the insiders' trading information is publicly available. When insiders select a mixed strategy of AR (1) process as the information exposure strategy in a multi‐period model, we find the optimal AR (1) coefficient that maximizes the insiders' profit is negative. Also, (1) the greater the transaction volume of mimicking traders in the market and the longer the information exposure period, the closer the optimum AR (1) coefficient becomes to −1; (2) The larger the mimicking transaction volume, the smaller the insider's profit gets; and (3) When the volume of mimicking transaction is large and the private information is not much valuable, the likelihood of loss is high. We also validate certain theoretical results of our model using publicized ownership change data of major shareholders. As a result, we find the strategic evidences in the sample of insider transactions closing within 15 trading days. Also, although mimicking traders' losses have not been reported, they can suffer losses when the private information is not much valuable and the insiders take a significant strategic action.