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 Stratasys (NASDAQ:SSYS) gained 1% in premarket trading Friday after Jefferies assumed coverage on the 3-D printing technologist with a buy rating.

So what: Along with the bullish call, analyst Jason North planted a price target of $140 on the stock, representing about 35% worth of upside to yesterday's close. So while momentum traders might be turned off by Stratasys' year-to-date pullback, North's call could reflect a sense on Wall Street that its growth prospects are becoming too cheap to pass up.

Now what: Stratasys replaces 3D Systems as Jefferies' "Top Pick" in the sector. "Stratasys is the most leveraged toward prototyping and prosumer/education," said North. "Rather than compete in the low end of the consumer market, Stratasys has actually raised MakerBot prices and included additional functionality as it targets the prosumer/education market. SSYS is putting a lot of SSYS IP into the new MakerBot machines (e.g., the architecture of the MakerBot Z18 (to be launched soon) is designed to include two heads and dual materials so it will possibly be upgradeable)." When you couple that competitive edge with Stratasys' rock-solid balance sheet and still-beaten down stock price, it's tough to disagree with Jefferies' bullishness. 

Brian Pacampara has no position in any stocks mentioned. The Motley Fool recommends 3D Systems, Apple, and Stratasys. The Motley Fool owns shares of 3D Systems, Apple, and Stratasys. 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.