McKesson is trading 4.96% lower at $960.34 in pre-market on October 20, with no confirmed overnight announcement or clearly established catalyst directly explaining the decline. - A market update described the prior session’s close near a 52-week high and an eight-day winning streak, but neither establishes the reason for this move. - Supplied market indicators are mixed, not a strong same-direction broad-market move that clearly explains the drop. - Recent bullish analyst commentary and reaffirmed fiscal 2027 guidance are background, not evidence of a fresh catalyst.