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 Qlik Technologies (NASDAQ:QLIK) climbed 2% this morning after Jefferies upgraded the business software specialist from hold to buy.

So what: Along with the upgrade, analyst Ross MacMillan boosted his price target to $35 (from $29), representing about 29% worth of upside to yesterday's close. While momentum traders might be turned off by the stock's slump in recent months, MacMillan believes Qlik is now too cheap to pass up given Wall Street's seemingly low expectations.

Now what: According to Jefferies, Qlik's risk/reward trade-off is rather attractive at this point. "Our most recent channel survey work was positive (esp. given weak 3Q13 results), we think the model set-up for CY14 is reasonable, valuation is more attractive and the Qlikview Next product release could help sentiment in CY14 and fundamentals in CY15," noted MacMillan. When you couple that possible upside with Qlik's sluggish stock price -- still off about 25% from its 52-week highs -- it's tough to disagree with Jefferies' bull call.