Misreading the Green: Study of Tiger's Toll Misses

Attempts to Quantify the Economic Impact of News Events Often Amount to Long Shots; the Traps of Interpreting Market Reaction

But investors often overreact to news -- a point overlooked when examining share-price changes, says Derek Oler, associate professor of accounting at Texas Tech University. In fact, many people pay experts to actively manage their money by exploiting inefficiencies such as market overreactions. "If the market was completely efficient, then active management is a fantastic fraud," Dr. Oler wrote in an email.

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