TORONTO (REUTERS) - Shares of BlackBerry rose nearly 6 per cent in trading before the opening bell on Monday after Bernstein Research said it was upgrading the stock to "outperform" after last week's launch of the company's new line of BlackBerry smartphones.

The brokerage firm, which has not had an "outperform" rating on the stock for over three years, also lifted its price target to US$22 (S$27) from US$12, saying it has grown more confident in the likely success of the devices, which are powered by the new Blackberry 10 operating system.

Shares of BlackBerry, which is changing its name from Research In Motion, rose 5.9 per cent to US$13.79 in premarket trading. The stock will begin trading under the "BBRY" symbol on Nasdaq on Monday.

As of Monday, shares of BlackBerry also begin trading under the "BB" symbol on the Toronto Stock Exchange. The stock used to trade as "RIMM" on the Nasdaq and "RIM" on the TSX.

"We upgrade Blackberry to outperform today as we believe BB 10 is set for a strong launch," Bernstein analyst Pierre Ferragu said in a note to clients. "Even if the long-term prospects for the platform are very uncertain, we believe all is in place for BlackBerry 10 to enjoy a great debut."

BlackBerry, a one-time pioneer in the smartphone industry, has ceded market share in recent years to the likes of Apple's iPhone, Samsung's Galaxy line and a slew of devices powered by Google Inc's market-leading Android operating system.

In a make-or-break move to regain market share and return to profitability, BlackBerry introduced its new line of smartphones to much fanfare last Wednesday.

However, its stock fell more than 10 per cent following the launch as investors were disappointed that its new smartphones will only go on sale in the crucial US market in mid-March.