Shares of Research In Motion fell around 15 percent on Friday after the BlackBerry maker reported a lower profit and gave an outlook that fell short of analysts' expectations.
Goldman Sachs cut its rating on the stock to neutral from buy, citing doubts about the company's ability to maintain market share in North America.
In addition, a second consecutive decline in international sales tempers our expectations for share gains overseas, Goldman analyst Simona Jankowski wrote in a note to clients.
Research in Motion's U.S.-traded shares fell to $70.42 shortly after the market opened. They closed on Thursday at $83.06 on the Nasdaq.
The company's Canadian shares fell to C$77.03, down from a close of C$90.16 on the Toronto Stock Exchange.
RIM is unlikely to maintain its over 50 percent share in North America in the face of increasing competition from Apple, Motorola, and Palm, among others, as even in a still-benign competitive environment and with two newly launched products, RIM lost share for the second consecutive quarter, said Jankowski.
Brokerage firm Raymond James also cut its rating on RIM to market perform from outperform.
Phillip Huang, an analyst at UBS, maintained a neutral rating on RIM, saying its shares will likely be range-bound until the company can show stronger top line momentum.
He added that sentiment could be muted near-term due to increasing competition & a potential relationship between Apple and Verizon Wireless.
(Reporting by Euan Rocha and John McCrank, editing by Dave Zimmerman)