Merger negotiations routinely occur amidst economically significant a target stock price runups. Since the source of the runup is unobservable (is it a target stand-alone value change and/or deal anticipation?), feeding the runup back into the offer price risks "paying twice" for the target...

Do pre-offer target stock price runups increase bidder takeover costs? We present model-based tests of this issue assuming runups are caused by signals that inform investors about potential takeover synergies. Rational deal anticipation implies a relation between target runups and markups (offer...