NEW YORK ( TheStreet) -- Facebook ( FB) was a big loser in premarket trading on Thursday as investors responded to the company's fourth-quarter results, which were released after Wednesday's closing bell. Despite beating Wall Street's expectations, Facebook shares fell 5.25% to $29.60 before market open on concerns about the company's spending. Facebook's costs and expenses rose sharply during the fourth quarter, jumping 82% year over year to $1.06 billion, although Chief Financial Officer David Ebersman told TheStreet that he isn't concerned. "Our key issues are investments in our people Facebook ended the quarter with over 4,600 employees and infrastructure," he said, during an interview. "We are investing in engagement and monetization, and we're showing the results." Excluding items, Facebook reported earnings of 17 cents a share on a 40% jump in revenue to $1.585 billion. Revenue from advertising was up 41% to $1.33 billion, accounting for 84% of total revenue. Mobile revenue represented 23% of advertising revenue in the fourth quarter, up from 14% in the third quarter. The Menlo Park, Calif.-based firm was also the most active premarket Nasdaq stocks on share volume of 5,619,535. Research In Motion ( RIMM) shares were also under pressure before market open despite the long-awaited launch of the company's BlackBerry 10 technology on Wednesday. The Canadian handset maker, which also changed its name to BlackBerry at a glitzy event in New York, unveiled the much-delayed operating system and two new smartphones -- the touchscreen Z10 and the Q10, which features a physical QWERTY keyboard. "We have definitely been on a journey of transformation," said CEO Thorsten Heins, kicking off the company's event in New York, adding that BlackBerry will transform mobile communications into mobile computing. Investors were decidedly unmoved. RIM shares were off 5.95% at $12.96 before market open after tumbling 12.01% in Wednesday's session. RIM was another of the most active premarket Nasdaq stocks on share volume of 1,565,412. Qualcomm ( QCOM) shares, however, climbed 6.64% to $67.75 on share volume of 220,884 after the chipmaker blew past Wall Street's fiscal first-quarter estimates and offered robust guidance. The San Diego-based firm reported revenue of $6.02 billion, a 29% increase from a year earlier and well above analysts' forecasts of $5.9 billion. Excluding items, Qualcomm earned $1.26 a share, a rise of 30%. Analysts surveyed by Thomson Reuters were looking for earnings of $1.13 a share.