$MCK is one of biggest losers #stocks today. read more:

McKesson Corporation Common Sto (symbol: MCK) was one of the worst losers
of the trading day today (2016-10-28), losing -22.67%. The number of shares
that changed hands was 28,125,416, or about 18 times the average daily
volume in the stock.
The closing price was $124.11, amounting to a market cap of
$28,010,000,000, about -38.62% off the highest price in the last 12 months.
The stock has been trading at a range between $114.53 and $202.2.
MCK is in the Other Pharmaceuticals industry, part of the Health Care
sector.
Looking at its valuation, the stock is now trading at 12.89 times earnings.