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 Sprint Corporation (NYSE:S) climbed as high as 4% today after Nomura Securities upgraded the telecom giant from neutral to buy.

So what: Along with the upgrade, analyst Adam Ilkowitz raised his price target to $10.50 (from $6), representing about 32% worth of upside to yesterday's close. While value investors might be turned off by Sprint's steady share-price climb in recent months, Ilkowitz believes that there's plenty of room to run given his forecast of strong EBITDA and free cash flow improvement.

Now what: Ilkowitz now expects Sprint to post per-share losses of $0.89 in 2013 and $0.40 in 2014, both up significantly from his prior estimates. "We believe operating cost reductions should be seen in two buckets: lower project spending (iDEN, Network Vision, roaming) and flat ongoing expenses," Nomura noted. "Our estimates are ahead of consensus, though they are more conservative than Sprint's publicly disclosed forecasts in the proxy filings." When you couple Sprint's still-worrisome trend of steep subscriber losses with its red-hot stock price, however, waiting for a wider margin of safety seems like the prudent move at this point. 

Fool contributor Brian Pacampara has no position in any 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.