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: Whole Foods Market (Nasdaq: WFMI) popped 13% in intraday trading today after the company reported first-fiscal-quarter EPS of $0.51, soundly beating the $0.46 consensus estimate, and raised revenue, same-store sales, and EPS guidance for the fiscal year.

So what: The new EPS guidance is $1.25 to $1.29 for the remaining three quarters in the fiscal year, compared to a consensus of $1.25, so estimates are likely to increase by a penny or two per quarter. Same-store sales growth showed the fifth consecutive quarter of positive momentum over both one and two years and management raised guidance for the fiscal year from 5%-7% to 7%-9%.

Now what: EPS grew an impressive 59% year-over-year in the most recent quarter, but the updated guidance implies EPS growth will slow to 14% to 17% for the remainder of the fiscal year. Management cited tougher sales comparisons, expenses for store pre-openings and relocations, and inventory accounting changes for the slowdown in earnings growth. At a price of $60.11, the stock's P/E ratio of 42.0 times trailing earnings and about 32 to 33 times forward earnings estimates seems rich given the EPS growth outlook for the remainder of the year.

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Fool contributor Cindy Johnson does not own shares of any company named above. Whole Foods Market is a Motley Fool Stock Advisor pick. 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.