While Fools should generally take the opinion of Wall Street with a grain of salt, it's not a bad idea to take a look at particularly stock-shaking analyst upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of Trimble Navigation Limited (NASDAQ:TRMB) popped 2% today after J.P. Morgan upgraded the GPS technologist from Neutral to Overweight.

So what: Along with the upgrade, analyst Paul Coster boosted his price target to $43 (from $36), representing about 10% worth of upside to yesterday's close. While contrarians might be turned off by Trimble's share price surge in recent months, Coster thinks there's more room to run given the strong operating tailwinds continuing to work in its favor.

Now what: According to J.P. Morgan, Trimble's risk/reward trade-off is pretty attractive at this point. "We are raising estimates slightly to reflect positive momentum in E&C and improved margins from the firm's strategic shift into higher-value software and services, and we are upgrading TRMB to Overweight from Neutral," said Coster. "Improving cyclical prospects in construction and in enterprise IT bode well for TRMB's E&C and mobile segments heading into 2014, and the firm's long-term growth prospects remain compelling owing to the transition into geospatial business intelligence, which we view as a secular growth opportunity." Of course, with the stock now up about 50% over the past six months and trading at a 45-plus P/E, I'd wait for a much wider margin of safety before buying into those prospects. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.