Benzinga's Top #PreMarket Losers

shares fell 22.26 percent to $16.10 in pre-market trading after the company reported weaker-than-expected Q1 results and issued a weak FY15 guidance.

fell 20.81 percent to $9.36 in pre-market trading after the company reported downbeat Q2 revenue and issued a weak revenue outlook. The company also named Brian Swartz as chief financial officer.

shares dropped 5.78 percent to $11.41 in pre-market. Enphase reported Q1 adjusted loss of $0.07 per share on revenue of $86.7 million.

slipped 2.11 percent to $165 in pre-market trading. Alexion Pharmaceuticals announced its plans to acquire

for $8.4 billion and raised share repurchase authorization to $1 billion.

shares declined 2.05 percent to $6.70 in pre-market trading. Groupon reported better-than-expected earnings for the first quarter, but the company's sales missed analysts' estimates.