Morning Market Losers

shares dipped 24.44 percent to $27.70 after the company presented data from MGCD265 showing preliminary evidence of clinical efficacy at the ASCO. Brean Capital downgraded Mirati Therapeutics from Buy to Hold.

shares dropped 14.91 percent to $1.94 after the company announced an update on its lead product, IMP321.

shares fell 13.47 percent to $8.03. Jiayuan.com reported that it has received additional non-binding proposals.

shares slipped 3.94 percent to $88.80 after the company reported updated Phase 2 results from two ongoing clinical studies with rucaparib: ARIEL2 and Study 10.

shares declined 2.49 percent to $28.15 after the company presented positive results from randomized, double-blind Phase 2 study of RINTEGA at the ASCO.

shares dropped 2.07 percent to $85.34. Raymond James downgraded Express Scripts Holding from Outperform to Market Perform.

shares declined 1.37 percent to $123.97. Citigroup downgraded F5 Networks from Buy to Neutral and raised the price target from $122.00 to $132.00.