(Story updated to reflect more premarket news and stock price changes)
NEW YORK ( TheStreet) -- LTX-Credence ( LTXC) shares were skyrocketing by 35.5% to $8.10 in premarket trading as the diversified test equipment maker and semiconductor test systems maker Verigy ( VRGY) said on Thursday they will merge to form an even larger test systems company. Verigy shares closed at $8.91 Wednesday, down 1.2%.
Shares of silver producer Silvercorp Metals ( SVM) were surging by 18.7% to $13.50 in premarket trading as silver prices continue to climb. "Silver investment continues to grow rapidly in 2010, with global holdings in exchange-traded funds backed by physical silver holdings at their highest recorded levels, and U.S. silver bullion coin demand set to outpace last year's record sales," according to the Silver Institute.
Biotech company Exelixis ( EXEL), which focuses on cancer treatments, was surging by 27.1% to $6 in premarket trading as it reported "promising interim data" for its XL184 treatment in ovarian cancer patients.
Sodastream International ( SODA) shares were 5.9% higher to $32.67 in premarket trading. The Israeli maker of home carbonated beverage systems raised $109.5 million at its IPO of 5.5 million shares earlier this month, after setting the pricing at $20 a share -- the high end of the range it was expecting. Analysts believe that its products are loaded with potential in the U.S. market.
Aruba Networks ( ARUN) was jumping by 6.5% to $22.70 in premarket trading after the Sunnyvale, Calif. company swung to first-quarter profit and posted a revenue surge.
Sears ( SHLD) fell **4.5% to $63.25** in premarket trading after the company reported a big loss for the third quarter ended Oct. 30.
A-Power Energy Generation Systems ( APWR ) fell 8.5% to $6 in premarket trading Thursday after the Chinese wind turbine manufacturer postponed a conference call about its third-quarter earnings originally scheduled for the day without providing a reason.
Qualcomm ( QCOM) was up 1.4% to $48.66 in premarket trading. On Wednesday. the company reassured investors that it would keep inventory levels low in 2011, placating concerns about a buildup of chip inventory.
Staples ( SPLS) lost 0.4% to $20 in after-hours trading. On Thursday, the company reported a rise in third-quarter profit due to cost-cutting. There were no premarket trades Thursday on Staples.
Ford ( F) was rising by 0.7% to $16.80 in premarket trading with news that the automaker cut its stake in Japanese automaker Mazda to 3.5%.