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 Symantec Corporation (NASDAQ:SYMC) plunged more than 10% during intraday trading Thursday after the company posted better-than-expected quarterly results, but followed with disappointing forward revenue guidance

So what: Quarterly revenue fell 5% year over year, to $1.7 billion, which resulted in adjusted earnings of $0.51 per share, or 13% growth during the same period. Both numbers handily beat Wall Street's expectations for earnings of just $0.43 per share on sales of $1.65 billion.

The market was less enthused, however, about Symantec's forward guidance, which calls for lower-than-expected fiscal fourth-quarter 2014 revenue of $1.615 billion to $1.655 billion, and in-line adjusted earnings per share between $0.40 and $0.42.

Now what: To Symantec's credit, the top-line guidance miss wasn't that bad; analysts were only modeling current quarter sales at $1.64 billion, or just barely above Symantec's $1.635 billion midpoint. That could also explain why shares of Symantec recovered some of their early losses to close down around 7%.

Nonetheless, investors remain leery as Symantec's top-line continues to struggle -- a concern Symantec CEO Steve Bennett highlighted by saying, "While we won't be happy until total business activity is growing again, I'm happy with our financial results given the massive changes in our business."

After today's pullback, shares do look relatively cheap around 11.7 times next year's estimated earnings. But I'm not particularly compelled to buy just yet. For now, I'm perfectly happy adding Symantec to my watchlist to keep tabs on its progress during the next few quarters.

Steve Symington 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.