The top after-market NYSE gainers Wednesday were Boston Beer, Kemet Corp, Wolverine World Wide, Best Buy and Medifast. The top after-market NYSE losers were Harbinger Group, Regal Beloit Corp, Petrobras Argentina, Roundy's and Barnes & Noble Inc.

Gainers

Boston Beer Co Inc. (SAM) shares climbed 12.49 percent to $128.50 in post- market target trading. The company currently expects the fiscal 2012 earnings to be in a range of $4.30 to $4.60, up from $3.80 to $4.20 and also topped Reuters’ estimate of $4.21 per share.

Kemet Corp. (KEM) shares gained 4.49 percent to $4.65 in post-market trading. The company stock plunged more than 4 percent in regular trading.

Wolverine World Wide, Inc. (WWW) shares gained 3.88 percent to $42.28 in post-market trading. The stock has a 52-week low of $33.30, a 52-week high of $47.99 and $1.99 billion in market capitalization.

Best Buy Co. Inc. (BBY) shares surged 3.45 percent to $12.60 in post-market trading. The stock has a 52-week low of $11.41, a 52-week high of $27.95 and $4.12 billion in market capitalization.

Medifast Inc. (MED) shares gained 3.30 percent to $32.28 in post-market trading. The company stock declined more than 3 percent in regular trading.

Losers

Harbinger Group Inc. (HRG) shares tumbled 15.36 percent to $8.65 in post-market trading. The company Wednesday announced a registered secondary public offering of shares of its common stock by Harbinger Capital Partners Master Fund I Ltd., Harbinger Capital Partners Special Situations Fund, L.P. and Global Opportunities Breakaway Ltd.

Regal Beloit Corp. (RBC) shares plunged 3.54 percent to $67.75 in post-market trading. The company announced Wednesday that it had commenced a public offering of 2,750,000 shares of common stock.

Petrobras Argentina S.A. (PZE) shares declined 3.54 percent to $4.91 in post-market trading. The stock has a 52-week low of $3.40, a 52-week high of $8.61 and $1.03 billion in market capitalization.

Roundy's Inc. (RNDY) shares fell 3.25 percent to $4.70 in post-market trading. The company stock climbed more than 6 percent in regular trading.

Barnes & Noble Inc. (BKS) shares declined 2.51 percent to $15.51 in post-market trading. The stock has a 52-week low of $9.35, a 52-week high of $26.00 and $953.05 million in market capitalization.

Best buy