While Fools should generally take the opinion of Wall Street with a grain of salt, it's not a bad idea to take a closer look at particularly stock-shaking upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of BlackBerry Ltd. (NYSE:BB) surged 5% in pre-market trading after FBR Capital upgraded the wireless technologist from underperform to market perform.

So what: Along with the upgrade, analyst Scott Thompson planted a price target of $10 on the stock, representing about 11% worth of upside to Friday's close. While contrarians might be turned off by BlackBerry's strong rebound in recent months, Thompson thinks there might be room to bounce given the several positive trends -- refreshed management, shift into higher growth segments, and rapid cash-generating asset sales -- working in its favor.

Now what: According to FBR, BlackBerry's risk/reward trade-off seems to be stabilizing. "While we find it probable that a true turnaround could take several additional quarters to take form, we see potential for more upside well before needing to focus on potential downside in shares," noted Thompson. When you couple BlackBerry's strong share price of late with the uncertainty continuing to surround its future, however, I wouldn't bet too much on a long-term turnaround just yet.