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 Lululemon Athletica (NASDAQ:LULU) rose as much as 9.7% Thursday, then settled to trade up around 6.5% as of 2:30 p.m. after the yoga apparel specialist reported better-than-expected fourth-quarter earnings.

So what: Quarterly revenue rose 16% year over year (or 20% on a constant-currency basis) to $602.5 million. Total comparable sales climbed 8% for the quarter on a constant dollar basis, including a 5% jump in comparable-store sales and a 20% increase in direct-to-consumer revenue. That translated to a slight increase in net income to $110.9 million, and, thanks to lululemon's share repurchase efforts, a 4% jump in diluted earnings per share to $0.78. Analysts, on average, were only modeling earnings of $0.73 per share on slightly lower revenue of $602.4 million.

"Our solid performance in the fourth quarter builds on the momentum that began in the third quarter and reflects improved traffic and a strong guest response," added Lululemon CEO Laurent Potdevin. "2014 was a critical year when we strengthened our leadership team and made important investments in our product pipeline, guest experience, brand, and community engagement."

Now what: Going forward, however, lululemon expects current-quarter revenue of $413 million to $418 million, with diluted earnings per share of $0.31 to $0.33. Wall Street was looking for first-quarter 2015 earnings of $0.39 per share on sales of $442 million.

For the full year 2015, lululemon sees revenue of $1.97 billion to $2.02 billion, helped by a comparable-store sales increase in the mid-single digits. That should result in 2015 earnings per share of $1.85 to $1.90. Again, both ranges fell short of analysts' expectations, which called for 2015 sales and earnings of $2.05 billion and $2.06 per share, respectively.

On that note, keep in mind lululemon has a long-standing penchant for underpromising and overdelivering, so watching it issue conservative guidance is nothing new. In the end, as a shareholder myself, that's why I'm perfectly content knowing this solidly profitable company is still moving in the right direction after a difficult past two years.

Steve Symington owns shares of Lululemon Athletica. The Motley Fool recommends Lululemon Athletica. The Motley Fool owns shares of Lululemon Athletica. 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.