The top after-market Nasdaq gainers Friday were Idenix Pharmaceuticals Inc, Achillion Pharmaceuticals, Mattress Firm Holding Corp, MCG Capital Corporation and Layne Christensen Company.

The top after-market Nasdaq losers were Allied Healthcare Products, JAKKS Pacific Inc, Kandi Technologies Corp, Kayak Software Corporation and Savient Pharmaceuticals.

Gainers

Idenix Pharmaceuticals Inc (IDIX) shares climbed 4.17 percent to $4.75 in post-market trading. The company shares have a 52-week trading range of $4.30-$15.25 and a market capitalization of 595.41 million.

Achillion Pharmaceuticals Inc (ACHN) shares surged 3.22 percent to $10.74 in post-market trading. The company shares have a 52-week trading range of $3.81-$12.95 and a market capitalization of 754.72 million.

Mattress Firm Holding Corp (MFRM) shares advanced 3.09 percent to $29.02 in post-market trading. The company stock had lost 3 percent in regular trading Friday.

MCG Capital Corporation (MCGC) shares rose 3.04 percent to $4.75 in post-market trading. The company shares have a 52-week trading range of $3.40 - $5.36 and a market capitalization of 340.73 million.

Layne Christensen Company (LAYN) shares gained 2.86 percent to $20.17 in post-market trading. The company stock had lost 2.78 percent in regular trading Friday.

Losers

Allied Healthcare Products (AHPI) shares plunged 17.18 percent to $2.62 in post-market trading. The company Friday reported a loss for the fourth quarter and the fiscal year on sales depressed by the lingering effects of recession and uncertainty about future healthcare legislation. Shares of the company plummeted 16.03 percent in regular trading.

JAKKS Pacific Inc (JAKK) shares declined 8.03 percent to $13.40 in post-market trading. The shares dropped after the toymaker lowered its guidance for the full year 2012 citing "disappointing" sales. The company announced Friday that it expected the adjusted earnings of $0.68 to $0.74 per share on revenues of $690 million to $700 million against the analysts’ expectation of earnings of $1.09 per share on revenues of $732.15 million for fiscal year 2012.

Kandi Technologies Corp (KNDI) shares plunged 3.48 percent to $3.88 in post-market trading.  

Savient Pharmaceuticals (SVNT) shares declined 3.20 percent to $2.42 in post-market trading. The company shares gained over 12 percent in regular trading.

Kayak Software Corporation (KYAK) shares fell over 1 percent to $34.90 in post-market trading.