Benzinga's Top #PreMarket Losers

Relypsa Inc RLYP fell 13.93 percent to $13.90 in pre-market trading following Wednesday's FDA approval of the company's treatment for Hyperkalemia. Tenet Healthcare Corp THC shares declined 10.89 percent to $31.01 in pre-market trading after falling 4.47 percent on Wednesday. Horizon Pharma PLC HZNP shares fell 4.25 percent to $14.20 in pre-market trading after the company reported the US PTO issuance of added notice of allowance with claims covering PENNSAID 2%. American Express Company AXP shares tumbled 3.93 percent to $73.50 in pre-market trading after the company reported weaker-than-expected earnings for the third quarter. Caterpillar Inc. CAT shares dipped 2.54 percent to $67.90 in pre-market trading after the company reported weaker-than-expected earnings for the third quarter and lowered its FY15 earnings forecast.