The top after-market Nasdaq gainers Tuesday were Obagi Medical Products Inc, Xyratex Ltd, OraSure Technologies Inc, MannKind Corporation and Smith & Wesson Holding Corporation.

The top after-market Nasdaq losers were VOXX International Corporation, Prospect Capital Corporation, Golar LNG Partners LP, Arena Pharmaceuticals Inc and Jamba Inc.

Gainers

Obagi Medical Products Inc (OMPI) shares climbed 18.50 percent to $11.45 in after-hours trading Tuesday.  The company's shares have surged on shorting by the investors, who are acting on rumors about the company's acquisition. Cantor Fitzgerald's analyst Irina Rivkind said Tuesday that the company could be attractive to multiple suitors. 

Shares of Xyratex Ltd (XRTX) rose 7.77 percent in the post-market session to close at $12.35. The data storage provider's shares had slumped 7.69 percent in regular trade Tuesday. The company has a 52-week low of $7.58, a 52-week high of $17.96 and $319.87 million in market capitalization.   

OraSure Technologies Inc (OSUR) shares advanced 2.92 percent to $12.70 in post-market trading. The company announced the pricing of an underwritten offering of 6,100,000 shares of its common stock at a price of $12.30 per share. After the underwriting discount and estimated offering expenses, OraSure expects to receive net proceeds of approximately $70.2 million, as reported by Reuters.

MannKind Corporation (MNKD) shares gained 1.92 percent and reached $2.66 in after-hours trading. The development-stage biopharmaceutical company stocks had slumped 9.38 percent in regular trade Tuesday.  

Smith & Wesson Holding Corporation (SWHC) shares surged 1.74 percent to $9.37 in after-hours trading Tuesday. The shares of the company have a 52-week low of $2.29, a 52-week high of $9.50 and $6011.71 million in market capitalization.

Losers

VOXX International Corporation (VOXX) shares slumped 15.86 percent to $8.82 in the post-market session Tuesday. The Audio equipment maker reported a worse-than-expected quarterly loss, mainly due to a patent litigation settlement charge and expenses related to the company's acquisition of Germany's Hirschmann.

The company reported a loss of $4.7 million or 20 cents per share, against a net income of $2.5 million or 11 cents per share a year ago and analysts' expectation of 10 cents per share gain.

Prospect Capital Corporation (PSEC) shares plunged 8.90 percent to $6.30 in the post-market session. The company said it will offer 21 million shares of its common stock and granted Barclays a 30-day option to purchase up to 3.15 million additional shares.

Golar LNG Partners LP (GMLP) shares lost 4.20 percent in after-hours trading to reach $30.80. The company announced Tuesday the follow-on public offering of 5,500,000 common units at a price of $30.95 per unit. The Partnership has granted the underwriters a 30-day option to purchase up to an additional 825,000 common units.

Golar LNG has also agreed to purchase directly from the Partnership in a private placement 969,305 common units at a price of $30.95 per unit, such private placement to close concurrently with the public offering of common units.

Arena Pharmaceuticals Inc (ARNA) shares dropped 3.90 percent to $11.35 in after-hours trading. Shares of the clinical-stage biopharmaceutical company have a 52-week low of $1.23, a 52-week high of $13.50 and $2.16 billion in market capitalization.

Jamba Inc (ALSK) shares declined 2.32 percent to $2.53 in after-hours trading. The company shares have a 52-week low of $1.21, a 52-week high of $2.72 and 174.32 million in market capitalization.