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 CEC Entertainment (NYSE: CEC), which operates Chuck E. Cheese family restaurants, sank 11% today after its quarterly revenue and full-year outlook disappointed Wall Street.

So what: While CEC's bottom line surged 36% in the second quarter, a disconcerting demand trend has the shares flirting with new 52-week lows. Hurt by weak consumer spending and increased competition from PG-13 movies, CEC posted second-quarter revenue that came in below analyst estimates, with its same-store sales growing a measly 0.3%.

Now what: I'd continue to keep my distance from CEC. Management now sees full-year earnings of $2.75-$2.95 per share, versus Wall Street expectations of $3.03 in per-share earnings. While CEC's valuation might look decent at these levels, that bleak near-term outlook, coupled with a heavy debt load, should require a big margin of safety.

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