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: SUPERVALU (NYSE: SVU) shares fell 11% in early trading today on weak earnings and a disappointing outlook.

So what: Earnings excluding nonrecurring items were $0.28 per share, just below Wall Street's $0.29 expectation, and revenue lagged expectations as well. But the real news today was incredibly disappointing guidance. SUPERVALU lowered earnings guidance for fiscal 2011 to $1.40 to $1.60 per share, down from a previous guidance of $1.75 to $1.95 per share in July.

Now what: This Fool is usually skeptical of market panics on guidance, but SUPERVALU's lowering guidance just three months after original guidance has me worried about this stock. SUPERVALU's stock has lagged competitors like Kroger (NYSE: KR) year to date, and it appears the trend will continue. I would shy away from SUPERVALU until the company's expectations improve or it starts beating estimates and guidance to the upside.

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Fool contributor Travis Hoium does not have a position in any company mentioned. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw.

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