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 Telefonica Brasil SA (NYSE:VIV) gained 2.5% this morning after BTIG upgraded the Brazilian telecom giant from neutral to buy.

So what: Along with the upgrade, analyst Walter Piecyk planted a price target of $24 on the stock, representing about 34% worth of upside to yesterday's close. While momentum traders might be turned off by the stock's steady decline in 2013, Piecyk believes that strong industry tailwinds and operational improvement should fuel a rebound next year.

Now what: BTIG thinks Telefonica will be able to return to EBITDA growth in 2014. "We upgraded Telefonica Brasil to Buy from Neutral because we expect it to be the primary beneficiary of strong wireless data growth trends in Brazil," noted BTIG. "While Telefonica Brasil is not an acquisition target, it could also benefit from likely consolidation in Brazil." When you couple those compelling catalysts with Telefonica's 4.5%-plus dividend yield, it's tough to disagree with BTIG's call.

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.