Third-quarter profit at Motorola has more than tripled thanks to improved sales of mobile phones, but shares dipped due to concerns about the outlook for sales growth.
Motorola said earnings for the three months to September were $479m (£268m), up from $116m a year earlier.
Sales increased 26 per cent to $8.62 billion, but were below analysts' average estimate of $8.67 billion, according to Reuters Estimates.
Other company segments also performed well. Wireless sales rose 34 per cent to $3.9 billion, global telecom solutions sales 24 per cent to $1.3 billion, sales in the firm's commercial, government and industrial solutions unit rose 12 per cent to $1.2 billion; and its integrated electronic systems division, climbed 22 per cent to $683 million.
Motorola's semiconductor business – in the process of being spun-off as Freescale Semiconductor – notched up operating earnings of $82m. Sales rose 17 per cent on the year to $1.4bn. This compares to $76 million loss a year ago.
However, Freescale said that it would cut about 1,000 jobs, or 4.5 per cent of its workforce, which will cost $65 million in once-off charges.
Motorola produces the G4 chip used in Apple's PowerBooks and iBooks.
Chief executive Ed Zander said: "Customers are responding to our portfolio of new products and technologies by giving us market-share growth in several areas. We have a great product portfolio, with even better new phones on the way in the fourth quarter."
The company expects to gain market share in the fourth quarter, predicting that sales will rise to 20 per cent to a range of $9.3 billion and $9.6 billion.