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 Agnico Eagle Mines (NYSE:AEM) gained slightly this morning after TD Securities upgraded the gold miner from hold to buy.

So what: Along with the upgrade, analyst Greg Barnes boosted his price target to $42 (from $31), representing about 26% worth of upside to yesterday's close. So while contrarian traders might be turned off by Agnico's price strength in recent weeks, Barnes' call could reflect a sense on Wall Street that the company's growth prospects still aren't fully baked into the valuation.

Now what: According to TD, Agnico's risk/reward trade-off is rather attractive at this point. "Agnico deservedly trades at some of the highest valuation multiples in the gold sector, suggesting that investors agree with our positive view on the company's fundamental outlook," said Barnes. "We use the highest target multiples in our gold sector coverage universe to generate our target price -- 1.75x NAV and 15.0x 2015 CFPS -- which are in line with our target multiples for Goldcorp." When you couple Agnico's exposure to volatile resource prices with its red-hot stock price (up about 40% from its 52-week low), however, I'd hold out for a wider margin of safety before buying into that bullishness.