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: Jefferies upgraded communications company Charter Communications, (CHTR 2.04%) from hold to buy this morning.

So what: Along with the upgrade, analyst Mike McCormack boosted his price target to $150 (from $125), representing about 18% worth of upside to Friday's close. So while momentum traders might be turned off by the stock's sluggishness over the past several months, McCormack's call suggests that Wall Street is beginning to notice Charter's seemingly accelerating fundamental growth.

Now what: Management raised its 2014 EPS outlook for Charter from $1.23 to $1.77 and its 2015 outlook from $3.39 to $3.92. "While shares have lagged following a failed bid to acquire TWC, we believe the market is discounting CHTR's operational momentum, FCF growth, and likely leadership in further consolidation," said McCormack. "Our revised PT embeds no M&A benefits, yet we see double digit FCF/share growth from potential acquisitions, lending further support should M&A materialize." When you couple those operational tailwinds with Charter's share price weakness of late, it's tough to disagree with Nomura's bullish stance.