The top after-market NASDAQ stock market gainers are: Parexel International, hiSoft Technology International, Kforce, SodaStream International, Interactive Brokers Group, Stereotaxis, Pixelworks, LoopNet, Mellanox Technologies, and Ancestry.com.

Parexel International Corp. (PRXL) surged 5.90 percent to $19.37 in the after-market trading.

hiSoft Technology International Ltd. (HSFT) soared 5.64 percent to $28.26 in the after-hours session.

Kforce Inc. (KFRC) improved 5.32 percent to $16.22 in the after-market trading.

SodaStream International Ltd. (SODA) jumped 4.76 percent to $43.58 in the after-hours session. The company's third quarter adjusted profit was 3.9 million euros or 31 cents a share, up from 2.6 million euros or 21 cents a share last year. Revenue rose 51.7 percent to 42 million euros.

Interactive Brokers Group, Inc. (IBKR) climbed 4.21 percent to $18.30 in the after-market trading. The company said its board has declared a special cash dividend of $1.79 a common share, payable on Dec. 23 to shareholders of record Dec. 9.

Interactive Brokers said the aggregate pretax amount to be paid by its operating companies will be about $1 billion. The company expects to pay dividend from cash on hand. Cash and cash equivalents at the end of September 30, 2010 was $1.29 billion.

Stereotaxis Inc. (STXS) rose 3.64 percent to $3.70 in the after-hours session.

Pixelworks Inc. (PXLW) grew 3.44 percent to $3.61 in the after-market trading.

LoopNet, Inc. (LOOP) gained 3.23 percent to $11.51 in the after-hours session.

Mellanox Technologies, Ltd. (MLNX) increased 3.20 percent to $25.15 in the after-market trading. The company said it agreed to buy Voltaire Ltd.(VOLT) for $8.75 a share in cash or total equity value of about $218 million.

Ancestry.com Inc. (ACOM) moved up 3.05 percent to $29.77 in the after-hours session.

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