Most likely suspect in the selling are institutions that formerly held HBOC. That's probably who's worried about MCK/HBOC (I came to MCK from HBOC myself and wouldn't be holding if not for MCK).
Sometimes downward spirals simply feed on themselves...and until there's a selling climax (perhaps like last week) that takes out the last weak links, and the valuations become so appealing, the stock can't respond no matter who's recommending it. Dollar wise this is one of my 3 largest holdings (w/CSCO and AMGN) so it's disappointing to see this gross over reaction. However, if MCK hits earnings of $3.00 in FY2000 and $3.73 in calendar 2000 with rising orders at HBOC, IMHO we'll see 100 plus. However until a base is set, it's gut check time for us good guys. Personally I'm long thru 2000. Good investing.