The top after-market NYSE gainers on Friday were EPL Oil & Gas, Ellie Mae, Copa Holdings S.A., United States Cellular Corporation and Heckmann Corporation. The top after-market NYSE losers were Cooper Tire & Rubber Company, Magnum Hunter Resources Corp., Landauer Inc, Intrepid Potash Inc, and Penske Automotive Group.

Gainers

EPL Oil & Gas Inc. (NYSE:EPL) shares climbed 6.06 percent to $34.50 in post-market trading. The stock has a 52-week low of $14.56, a 52-week high of $35.14 and $1.28 billion in market capitalization.

Ellie Mae Inc. (NYSE:ELLI) shares surged 4.04 percent to $23.94 in post-market trading. The company stock plunged nearly 4 percent in regular trading on Friday.

Copa Holdings S.A. (NYSE:CPA) shares surged 3.34 percent to $139.72 in post-market trading. The stock has a 52-week low of $72.61, a 52-week high of $140.89 and $6 billion in market capitalization.

United States Cellular Corporation (NYSE:USM) shares gained 3.15 percent to $40.95 in post-market trading. The stock has a 52-week low of $33.16, a 52-week high of $41.54 and $3.32 billion in market capitalization.

Heckmann Corp. (NYSE:HEK) shares advanced 2.67 percent to $3.84 in post-market trading. The company announced on Friday that it has received stockholders’ approval at the company's annual meeting to change its corporate name to Nuverra Environmental Solutions Inc. The company’s shares will begin trading on the New York Stock Exchange under its new name with stock ticker symbol “NES,” effective as of market open on May 20, 2013. The stock has a 52-week low of $2.60, a 52-week high of $5.14 and $941.96 million in market capitalization.

Losers

Cooper Tire & Rubber Company (NYSE:CTB) shares plunged 6.75 percent to $24.06 in post-market trading. The company stock gained more than 7 percent in regular trading on Friday.

Magnum Hunter Resources Corp. (NYSE:MHR) shares declined 4.82 percent to $3.16 in post-market trading. The company said on Friday that it received a notice from the NYSE MKT (on which only the Company's preferred stock is listed for trading) stating that the company is not in compliance with Sections 134 and 1101 of the NYSE MKT's company guide due to the company's previously disclosed failure to timely file the Form 10-K and Form 10-Q.

Landauer Inc. (NYSE:LDR) shares declined 4.25 percent to $49.33 in post-market trading. The company stock gained 4.57 percent in regular trading on Friday.

Intrepid Potash Inc. (NYSE:IPI) shares declined 3.99 percent to $17.55 in post-market trading. The stock has a 52-week low of $16.88, a 52-week high of $24.70 and $1.38 billion in market capitalization.

Penske Automotive Group Inc. (NYSE:PAG) shares fell 3.94 percent to $31.05 in post-market trading. The company stock surged more than 4 percent in regular trading on Friday.

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