Down goes Mylan.

Pounded. 

Mylan NV (MYL) said Wednesday, June 13, that the U.S. Food and Drug Administration "has identified minor deficiencies" that the agency will relay in a letter later this month regarding Mylan's application for a generic version of  GlaxoSmithKline plc's (GSK) asthma drug Advair.

The FDA will issue a complete response letter, which indicates that an application is not yet ready for approval, on June 27.

Shares of Mylan fell 4.3% to $39.90 in after-hours trading. GlaxoSmithKline's American Depository Receipts were up 2.5% to $42.15.

"Because our Abbreviated New Drug Application has received a priority designation, our approval could be received prior to the standard 90-day time period following the date of our response to the Complete Response Letter," Mylan said.

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