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 Apple (NASDAQ:AAPL) climbed 2% today after Societe Generale upgraded the consumer electronics gorilla from hold to buy.

So what: Along with the upgrade, analyst Andy Perkins boosted his price target to $575 (from $500), representing about 13% worth of upside to yesterday's close. While bargain hunters might be turned off by the stock's surge since late June, Perkins still sees some upside left given his view of better-than-expected iPhone demand and possibly weakening Android competition.

Now what: Societe expects Apple to post strong Q4 results next Monday. "We are expecting sales of $38bn (cs $36.7bn, guidance $34bn to $37bn), gross margin of 36.9% (cs 36.8%, guidance 36% to 37%) and an EPS of $8.3 (cs $7.9, guidance $6.8 to $8.0)," noted Societe Generale. "The key question will be over the success of the new 5s and 5c iPhones." More important, with Apple shares still off about 20% from its 52-week highs and trading at a forward P/E of 12, there might be enough margin of safety built in to make betting on that success a relatively low-risk move. 

Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool recommends Apple. The Motley Fool owns shares of Apple. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.