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 SanDisk Corporation (UNKNOWN:SNDK.DL) gained 1% today after ISI Group upgraded the data storage technologist from neutral to strong buy.

So what: Along with the two-notch upgrade, analyst C. J. Muse boosted his price target to $110 (from $87), representing about 28% worth of upside to Friday's close. So while contrarian traders might be turned off by SanDisk's price strength over the past year, Muse's call could reflect a growing sense on Wall Street that its prospects still aren't fully baked into the valuation.

Now what: According to ISI, SanDisk's risk/reward trade-off remains attractive at this point. Specifically, Muse noted that the management is on a "clear path" to cost improvements on planar NAND and that it is in a particularly strong position to take advantage of growing enterprise storage demand. Of course, with the stock now up about 65% from its 52-week lows and trading at a near-20 P/E, I'd wait for some of the excitement to fade before buying into that bullishness.

Brian Pacampara has no position in any stocks mentioned, and neither does The Motley Fool. 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.