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 Micron Technology (NASDAQ:MU) rallied 2.5% this morning after Bank of America upgraded the semiconductor company from underperform to buy.

So what: Along with the two-notch upgrade, analyst Simon Dong-je Woo boosted his price target to $40 (from $22), representing about 35% worth of upside to yesterday's close. So while contrarian traders might be turned off by Micron's steady price strength over the past year, Dong-je Woo's call could reflect a sense on Wall Street that its growth prospects still aren't fully baked into the valuation.

Now what: According to B of A, Micron's risk/reward trade-off is particularly attractive at this point. "In our view, key catalysts are solid chip pricing environment (tight supply) and cost competitiveness," said Dong-je Woo. "Lower cyclical risk and higher shareholder return [should] lead to bigger EVA (WACC down vs ROE up)." Of course, when you couple Micron's still-significant debt load with its red-hot stock price -- now up a whopping 150% from its 52-week lows -- I'd hold out for a much wider margin of safety before betting on that bullishness.

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.