There are two criteria that are required to implement
this method. First, one needs a mechanism that identifies
positive net present value invesment opportunities.Sec-
ond, one needs to be able to observeinvestorreactionsto
these opportunities.Wedemonstratethatwecansatisfy
bothcriteriaifweimplementthemethodusingmutual
fund data.Undertheassumptionthataparticularasset
pricing modelholds,weusethemaininsightfrom Berkand
Green (2004) to showthatpositive(negative)abnormal
returnrealizationsinamutualfundinvestmentmustbe
associatedwithpositivenetpresentvaluebuying(selling)
opportunities. Wethenmeasureinvestorreactionstothese
opportunities byobser