The top after-market NYSE gainers Wednesday were Semiconductor Manufacturing, Imation Corp, USANA Health Sciences, GFI Group and RealD Inc. The top after-market NYSE losers were AU Optronics Corp, Roundy's, Omega Protein, Mine Safety Appliances and Quicksilver Resources.

Gainers

Semiconductor Manufacturing International Corp. (SMI) shares surged 3 percent to $2.75 in post-market trading. The stock has a 52-week low of $1.47, a 52-week high of $2.87 and $1.71 billion in market capitalization.

Imation Corp. (IMN) shares surged 2.79 percent to $4.36 in post-market trading. The stock tumbled more than 9 percent in regular trading after the company announced that it had acquired privately held Nexsan Corp for about $120 million.

USANA Health Sciences Inc. (USNA) shares gained 2.52 percent to $33.71 in post-market trading. The stock has a 52-week low of $30.51, a 52-week high of $50.23 and $474.32 million in market capitalization.

GFI Group Inc. (GFIG) shares rose 2.38 percent to $3.15 in post-market trading. The company stock plunged nearly 5 percent in regular trading.

RealD Inc. (RLD) shares advanced 1.65 percent to $11.17 in post-market trading. The company stock was reiterated with a “buy” rating at B. Riley Caris.

Losers

AU Optronics Corp. (AUO) shares plunged 6.25 percent to $4.48 in post-market trading. The company stock climbed more than 6 percent in regular trading.

Roundy's Inc. (RNDY) shares plunged 4.11 percent to $4.20 in post-market trading. The stock has a 52-week low of $3.69, a 52-week high of $12.50 and $199.96 million in market capitalization.

Omega Protein Corp. (OME) shares declined 3.84 percent to $6.60 in post-market trading. The company stock climbed more than 12 percent in regular trading.

Mine Safety Appliances Co. (MSA) shares fell 3.65 percent to $41.92 in post-market trading. The stock has a 52-week low of $32.65, a 52-week high of $44.34 and $1.61 billion in market capitalization.

Quicksilver Resources Inc. (KWK) shares declined 3.41 percent to $2.83 in post-market trading. The stock has a 52-week low of $2.62, a 52-week high of $7.18 and $506.74 million in market capitalization.

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