The maker of BlackBerry saw its shares plunge by more than 10% after reporting a fall in income and saying it would not be able to meet Wall Street's revenue forecasts. Canadian firm Research In Motion's second-quarter profit dropped to $463 million, down 4% on the same period a year earlier.

The decline was put down to charges for a patent settlement payment to mobile e-mail provider Visto, which claimed RIM was using its technology without a licence.

RIM revenue rose 37% but was still shy of the figure analysts had expected.

The company said it added only 3.8 million new subscribers during the period—the low end of its forecast - while revenues also came in shy of expectations despite jumping 37%.

Meanwhile revenue for the current quarter is seen coming in below the $3.8 billion tipped by analysts.

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