NYSE up
A trader glances at market indexes. Reuters

The top after-market NYSE gainers Friday were Hertz Global Holdings Ltd, Quicksilver Resources, Yingli Green Energy Holdings Co. Ltd, Nordic American Tanker Ltd and Office Depot Inc. The top after-market NYSE losers were Exelon Corporation, Cimarex Energy Co., NRG Energy Inc., Global Ship Lease Inc., and FirstEnergy Corp.

Gainers

Hertz Global Holdings Ltd. (NYSE:HTZ) shares surged 2.74 percent to $25.89 in post-market trading. The stock has a 52-week low of $10.22, a 52-week high of $26.05 and $10.09 billion in market capitalization.

Quicksilver Resources Inc. (NYSE:KWK) shares surged 2.36 percent to $2.60 in post-market trading. Moody's Investors Service downgraded Quicksilver Resources Inc.'s ratings, including the Corporate Family Rating (CFR) to B3 from B2, senior unsecured notes ratings to Caa2 from B3 and the subordinated notes rating to Caa2 from Caa1. Moody's also downgraded the company's Speculative Grade Liquidity Rating to SGL-4 from SGL-3. The outlook remains negative.

Yingli Green Energy Hold. Co. Ltd. (NYSE:YGE) shares gained 1.57 percent to $3.24 in post-market trading. The stock has a 52-week low of $1.25, a 52-week high of $4.83 and $486.90 million in market capitalization.

Nordic American Tanker Ltd. (NYSE:NAT) shares advanced 1.47 percent to $8.96 in post-market trading. The stock has a 52-week low of $8.15, a 52-week high of $13.88 and $484.14 million in market capitalization.

Office Depot Inc. (NYSE:ODP) shares rose 1.39 percent to $4.37 in post-market trading. The stock has a 52-week low of $1.51, a 52-week high of $6.10 and $1.23 billion in market capitalization.

Losers

Exelon Corporation (NYSE:EXC) shares slumped 2.54 percent to $33.77 in post-market trading. The stock has a 52-week low of $28.40, a 52-week high of $39.82 and $29.66 billion in market capitalization.

Cimarex Energy Co. (NYSE:XEC) shares plunged 1.99 percent to $70.87 in post-market trading. The stock has a 52-week low of $46.19, a 52-week high of $79.69 and $6.25 billion in market capitalization.

NRG Energy Inc. (NYSE:NRG) shares declined 1.91 percent to $26.65 in post-market trading. The company said on Friday that GenOn Energy Inc. ("GenOn"), one of its wholly owned subsidiaries, has given the required notice under the governing indenture to redeem for cash all of GenOn's remaining 7.625 percent Senior Notes due 2014 (the "2014 Notes") on June 24, 2013 (the "Redemption Date").

Global Ship Lease Inc. (NYSE:GSL) shares fell 1.83 percent to $4.42 in post-market trading. The stock has a 52-week low of $2.47, a 52-week high of $4.87 and $247 million in market capitalization.

FirstEnergy Corp. (NYSE:FE) shares declined 1.36 percent to $42.04 in post-market trading. The stock has a 52-week low of $38.26, a 52-week high of $51.14 and $17.82 billion in market capitalization.

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