What happened

Shares of Chart Industries (NASDAQ:GTLS) climbed 22.3% in December, according to data from S&P Global Market Intelligence, on the heels of an encouraging analyst note.

More specifically, Chart Industries' rise last month began in earnest on Dec. 5, when Stifel analyst Benjamin Nolan initiated coverage on the liquefied natural gas (LNG) and industrial gas systems specialist, assigning a buy rating and an $83-per-share price target.

LED display with Propane, Oil, and Gas prices with red and green arrows indicating direction.

IMAGE SOURCE: GETTY IMAGES.

So what

To justify his bullishness, Nolan called Chart his "favorite" play in the LNG space, arguing it should benefit given its exposure across the LNG supply chain. He also reminded investors of Chart's expectation for global LNG demand to increase a steady 5% annually for the next decade, while the industrial gas side should benefit from a "solid and more gradually growing base."

Now what

Of course, it wasn't terribly surprising to see Chart Industries bounce last month from its 52-week low on Nolan's vote of confidence. But keep in mind the stock closed yesterday at just over $68 per share, marking a nearly 18% discount from his target. And he's certainly not the only analyst to argue this energy stock is undervalued -- fellow Fool Jason Hall suggested as much in late October, and BTIG analyst Greg Lewis weighed in only yesterday with his own buy rating and $100 price target.

With this chorus of optimism surrounding Chart Industries today -- and assuming no massive macroeconomic disruptions to the LNG industry -- I won't be the least bit surprised to see shares continue to rally in the coming quarters.