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 Splunk, Inc. (SPLK) surged 7% today after Northland Capital Markets upgraded the data management software technologist from market perform to outperform.

So what: Along with the upgrade, analyst Tim Klasell planted a price target of $66 on the stock, representing about 43% worth of upside to Friday's close. So while momentum traders might be turned off by Splunk's sharp pullback in recent months, Klasell's call could reflect a sense on Wall Street that its growth prospects are now too cheap to pass up.

Now what: According to Northland, Splunk's risk/reward trade-off is particularly attractive at this point. "We expect positive FQ1 results with channel checks showing nice momentum into the end of the quarter," said Klasell. "Growing security use cases and awareness among users should help drive results in 2014. With increased focus on advanced persistent threats in the marketplace and Splunk's Enterprise Security App easing the implementation of security use cases in the organization, we expect continued strength in this vertical." When you couple that upbeat outlook with Splunk's cash-rich balance sheet and still-beaten down stock price, it's tough to disagree with Northland's bullishness.