Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of GNC Holdings (GNC) closed Thursday up more than 12%. The rise was been driven by GNC's strong fourth-quarter results, which beat Wall Street's expectations.

So what: GNC reported revenue of $607.2 million for its fourth quarter, which resulted in adjusted earnings of $0.61 per share. The company's top line drop $0.02 from the year-ago quarter. However, analysts had expected a worse performance, as their consensus was for $599.4 million in revenue and $0.59 in adjusted EPS.

Full-year EPS was the only primary metric to show a year-over-year improvement -- GNC's revenue for 2014 dropped by about 1% year over year to $2.613 billion, but its adjusted EPS rose 1% from the prior-year quarter's result to $2.87. That bottom-line figure topped Wall Street's consensus EPS estimate of $2.84. GNC now expects to earn approximately $3.10-$3.15 per share in its 2015 fiscal year, which is a bit weak in light of Wall Street's call for $3.15 in 2015 EPS.

Now what: Thursday's pop brings GNC back into positive territory for the past year, and its current guidance implies a forward P/E of roughly 15.5. The company also expects to produce a "low single digit increase" in same-store sales for the full year, which will result in its revenue growing to roughly $2.744 billion for 2015. That's good enough to beat Wall Street's $2.72 billion consensus, and GNC's shares offer a decent dividend to boot. I wouldn't expect explosive growth -- GNC is already a household name among the fitness set -- but slow and steady progress might be enough to justify taking a closer look.