The top after-market NASDAQ Stock Market gainers are: Xenoport, Bed Bath & Beyond, Immucor, Fortinet, and Tesco. The top after-market NASDAQ Stock Market losers are: Power-One, Tuesday Morning, Advanced Analogic Technologies, ISTA Pharmaceuticals, and Lincare Holdings.

Gainers

Xenoport, Inc. (XNPT) stock jumped 56.74 percent to $10 in the after-market trading, as GlaxoSmithKline Plc (GSK) and XenoPort gets FDA nod for Horizant. The U.S. Food and Drug Administration approved Horizant (gabapentin enacarbil) extended-release tablets for the treatment of moderate-to-severe primary Restless Legs Syndrome in adults. The companies said Horizant is the first drug in its class that the FDA has approved to treat moderate-to-severe primary restless legs syndrome.

Xenoport said Horizant is not recommended for patients who are required to sleep during the daytime and remain awake at night. The capacity of Horizant in the treatment of patients with moderate-to-severe primary Restless Legs Syndrome was demonstrated in two 12-week clinical trials in adults.

Bed Bath & Beyond, Inc. (BBBY) stock climbed 10.24 percent to $54.45 in the after-market trading, as its fourth quarter earnings and revenue topped Street view. Profit was $283.5 million or $1.12 a share, up from $226 million or $0.86 a share last year. Sales rose 11.6 percent to $2.5 billion. Analysts had expected profit of $0.97 a share on revenue of $2.39 billion. Comparable store sales grew about 8.5 percent.

Bed Bath & Beyond expects first quarter earnings of $0.58 to $0.61 a share, while Street predicts $0.60 a share. For the fiscal year ending next February, the company estimates earnings to grow by about 10 percent to 15 percent, while analysts project earnings of $3.33 a share. For the first quarter and the full year, the company projects sales growth at a mid-single-digit rate, and same-store sales growth of 2 percent to 4 percent.

Immucor Inc. (BLUD) stock grew 7.56 percent to $21.49 in the after-market trading, as its third quarter earnings and revenue topped Street view. Profit was $22.7 million or 32 cents a share, up from $20.1 million or 28 cents a share last year. Sales rose 4 percent to $83.35 million. Analysts had expected profit of 27 cents a share on revenue of $79.73 million.

The company said it expects to generate generate orders near the high end of its guidance range of 80 orders to 120 orders worldwide for NEO, while it expects to generate orders near the low end of its guidance range of between 140 orders and 180 orders worldwide for Echo for fiscal 2011.

Immucor narrowed its fiscal 2011 revenue guidance to a range of $328 million to $330 million from its prior forecast of $320 million to $332 million. The company raised its fiscal 2011 earnings outlook to range of $1.18 to $1.20 a share from its previous forecast of $1.08 to $1.18 a share. Street analysts predict profit of $1.14 a share on revenue of $327.36 million. Gross margins are expected to be toward the top end of the company's previous guidance range of 69.5 percent to 71.0 percent.

Fortinet Inc. (FTNT) stock gained 5.93 percent to $44.49 in the after-market trading.

Tesco Corp. (TESO) stock increased 4 percent to $22.11 in the after-market trading.

Losers

Power-One Inc. (PWER) stock fell 4.58 percent to $7.91 in the after-market trading, following a cut to its first quarter revenue guidance due mainly to adverse market conditions in the European solar market, with near-term feed-in-tariff uncertainty. The company lowered its first quarter revenue outlook to range of $240 million to $245 million from previous range of $260 million to $290 million, while Street predicts $275.53 million. Power-One is scheduled to report its earnings result on May 5.

Based on current developments, we still anticipate European countries such as Italy and Germany will continue to support solar adoption to reduce reliance on non-renewable sources of power. Further, for the remainder of 2011 and 2012, we believe we are better positioned to handle similar regional anomalies due to our expanded product line and focus on developing new markets, including the United States, China and India, said Richard Thompson, Chief Executive Officer of Power-One.

Tuesday Morning Corp. (TUES) stock slid 3.95 percent to $4.86 in the after-market trading.

Advanced Analogic Technologies, Inc. (AATI) stock slid 3.95 percent to $3.65 in the after-market trading. The company said Brian McDonald has resigned from his position as Vice President of Worldwide Finance, Chief Financial Officer, and Secretary to pursue other interests. Ashok Chandran, who is most recently serving as Vice President and Chief Accounting Officer, will become interim Chief Financial Officer, effective immediately.

ISTA Pharmaceuticals Inc. (ISTA) stock declined 3.94 percent to $10.25 in the after-market trading. In a regulatory filing, the company said consistent with its business development strategy to pursue potential opportunities with respect to late-stage and marketed prescription ophthalmic and allergy products, during the first quarter it incurred about $4.5 million to $5.5 million in legal, professional and other fees and expenses in connection with financing and due diligence activities to pursue the proposed acquisition of a company with marketed products.

The company said it was successful in securing a financing commitment for the acquisition, but was unsuccessful in concluding the transaction. The company reiterated its full year 2011 selling, general & administrative expenses guidance to remain in the range of 44 percent to 48 percent of revenue, however it expects such expenses to be at the higher end of the range. The company is making no other changes to its full-year 2011 financial guidance.

Lincare Holdings Inc. (LNCR) stock decreased 3.80 percent to $29.91 in the after-market trading.