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 natural food grocer Whole Foods (Nasdaq: WFMI) jumped more than 14% in intraday trading as investors reacted to the company's fiscal fourth-quarter earnings report.

So what: Beating earnings estimates and raising guidance is a recipe for investor jubilation the same way a Philadelphia Eagles loss at home to the New York Giants is a recipe for fisticuffs. Whole Foods' fourth quarter was a touchdown with the two-point conversion, though, as sales advanced 15%, comparable-store sales increased 8.7%, and earnings per share rose 63%. Earnings per share of $0.33 easily outran the $0.28 that Wall Street had in its playbook, while the new guidance for 2011 earnings -- with a midpoint at $1.69 per share -- hurdled the previous estimates by both the company and analysts.

Now what: Whole Foods today looks cheap compared with Whole Foods of a few years ago, but you've got to believe in very robust growth to digest the valuation premium that the stock gets over traditional grocers like Kroger (NYSE: KR) and Safeway (NYSE: SWY). That said, management sounds pretty confident about growth -- both from continued growth in current locations and the opportunity to open new locations.

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