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 3M Co. (NYSE:MMM) climbed 1% this morning after Nomura Securities upgraded the conglomerate from neutral to buy.

So what: Along with the upgrade, analyst Shannon O'Callaghan raised his price target to $150 (from $128), representing about 18% worth of upside to yesterday's close. While value investors might be turned off by the stock's steady rise over the past year, O'Callaghan believes there's plenty of room to run given his forecast of above-consensus growth over the next couple of years.

Now what: Nomura now expects 3M to post EPS of $6.75 in 2013, and $7.50 in 2014. "Organic growth is accelerating, capital allocation is turning positive, and margins may even have room to rise a bit, all suggesting to us that EPS growth could surprise to the upside versus current consensus estimates for 2014 and 2015," noted Nomura. "We expect all of that to benefit 3M's P/E, driving a potentially expanded and sustained higher multiple for 3M under the current Thulin/Meline management team." Of course, with the stock up 40% in 2013, and already trading at a forward P/E in the high teens, Fools might want to hold out for a wider margin of safety in case 3M doesn't grow as quickly as Nomura expects. 

Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool recommends 3M. 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.