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 flash-memory chip specialist SanDisk (UNKNOWN:SNDK.DL) climbed 6% this morning after posting better-than-expected third-quarter results and receiving a buy-to-strong-buy upgrade from Needham.

So what: Along with the upgrade, analyst Rajvindra Gill boosted his price target to $90 (from $80), representing about 43% worth of upside to yesterday's close. While value investors might be turned off by SanDisk's solid run in 2013, Gill believes that the Q3 results -- revenue jumped 28% -- coupled with upbeat Q4 guidance indicate that the operating momentum might only be getting stronger.

Now what: Needham sees several tailwinds working in SanDisk's favor. "SNDK should continue to benefit from an underlying favorable mix shift toward SSDs (specifically enterprise) and embedded, along with improving GM within each of its product lines," noted Needham. "Additionally, SNDK plans to use 70% of its FCF to repurchase shares; thus we believe we could see $0.20-0.30 EPS upside to our [estimates] just on stock buybacks alone." Of course, with SanDisk shares hitting a new 52-week high today and trading at a 20-plus P/E, I'd wait for a wider margin of safety before jumping in. 

Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. 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.