The price impacts of informed investors
研究识别了两类股票账户：一类利用盈利意外信息交易但价格影响为负且短暂，另一类基于公开信息交易且价格影响为正且持久，挑战了传统模型将永久价格影响归因于知情交易的观点。
We empirically identify a group of stock-exchange accounts that profit from 11 years of earnings surprises. Their trading behavior is consistent with privately informed trading, yet they have negative and temporary price impacts. We then empirically identify a second group of accounts that have positive and permanent price impacts. The trading behavior of the second group is more consistent with trading on public information, and they trade the wrong way before earnings surprises. The behavior of both account groups contrasts with models that associate permanent price impact with privately informed trading.