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 NPS Pharmaceuticals (UNKNOWN:NPSP.DL) climbed 2% today after Leerink Swann boosted its price target on the biotechnology company.

So what: While Leerink simply maintained its "outperform" rating on NPS, its new price target of $47 per share (from $35) represents about 43% worth of upside to yesterday's close. Leerink's findings from a recent survey of 30 endocrinologists highlight a significant unmet need in chronic hypoparathyroidism, suggesting that NPS' parathyroid hormone Natpara has even bigger sales potential than Wall Street thinks.

Now what: The next few months should be particularly eventful for NPS.

"[W]e are buyers of NPSP ahead of Natpara BLA filing in 4Q and additional details on management's view of the Natpara opportunity, which together, could broaden the Street's attention from the strong Gattex launch to Natpara's robust commercial potential in hypoPTH that we now project to be larger than Gattex at peak," wrote Leerink analyst Joseph Schwartz.

Of course, with the stock now up a whopping 360% from its 52-week lows and trading at a price-to-sales of 29, it's hard to believe that Mr. Market isn't already discounting most of that potential. 

Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool has no position in any of the 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.