Benzinga's Top #PreMarket Losers

shares fell 2.10 percent to $3.73 in pre-market trading. JP Morgan downgraded MannKind from Neutral to Underweight.

fell 1.32 percent to $12.71 in pre-market trading after rising 1.50 percent on Friday.

shares dropped 0.54 percent to $72.01 in pre-market. Morgan Stanley analysts maintained an Overweight rating on salesforce.com, with a price target of $80, while removing the company from the "Best Ideas" list.

shares declined 1.13 percent to $11.34 in pre-market trading after rising 3.52 percent on Friday.

slipped 0.29 percent to $48.98 in pre-market trading after the company announced its plans to buy Rosetta Resources Inc.

in a deal valued at $2.1 billion.