Shares in the Waterloo, Ontario-based company tumbled 14.04 per cent to $30.35 in electronic trading after the close of Wall Street.
The Canadian handset maker posted a net profit of $695 million, or $1.33 per share, in the first quarter of its 2012 fiscal year, compared with $769 million, or $1.38 per share, a year ago.
RIM, which is facing increased competition from Apple's iPhone and mobile phones running Google's Android software, said revenue grew 16 per cent to $4.9 billion, short of the $5.1 billion expected by Wall Street analysts.
RIM said it shipped 13.2 million BlackBerry smartphones during the quarter, down from 14.9 million last quarter, and 500,000 of its new BlackBerry Playbook tablet computers, RIM's answer to Apple's iPad.
RIM said it would begin cutting jobs in the second quarter as part of a plan to "streamline operations across the organization." It did not say how many jobs would be eliminated.
"Fiscal 2012 has gotten off to a challenging start," RIM co-chief executive Jim Balsillie said in a statement.
"The slowdown we saw in the first quarter is continuing into the second quarter, and delays in new product introductions into the very late part of August is leading to a lower than expected outlook in the second quarter."
RIM said it expected second quarter revenue of between $4.2 billion and $4.8 billion and earnings per share for fiscal 2012 were expected to be between $5.25 and $6.00, sharply less than the $7.50 forecast previously.
"RIM's business is profitable and remains solid overall with growing market share in numerous markets around the world and a strong balance sheet with almost $3 billion in cash," Balsillie said.
"We believe that with the new products scheduled for launch in the next few months and realigning our cost structure, RIM will see strong profit growth in the latter part of fiscal 2012."
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