There has been a growing concern about “killer acquisitions”, in which potential future competitors are bought up by large incumbents. To bring such transactions under merger scrutiny requires a screen to detect transactions that should be investigated more thoroughly. In this paper we develop such a screen, based on the idea that a high deal multiple can signal potential anticompetitive concerns of the transaction. We demonstrate a relationship between revenues (or employment) of a target and the deal multiple which allow the identification of outlier transactions. The filter identifies the transactions that have caused concern in public debate.