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 medical device company Tornier (NASDAQ: TRNX) plummeted 24% today after its quarterly results and outlook disappointed Wall Street.

So what: The stock has rallied nicely in recent months on optimism over accelerating growth, but a third-quarter miss -- loss of $0.18 in EPS was $0.03 worse than analysts expected -- coupled with downbeat guidance is forcing Mr. Market to quickly sober up. While Tornier's revenue increased 15% over the year-ago period, adjusted EBITDA margin slipped 110 basis points to 7.2%, suggesting that its competitive position is weakening.

Now what: Management now sees full-year revenue of $299.2 million-$303.2 million, well below Wall Street's forecast of $317.38 million.

"We believe we have the infrastructure in place to support our double-digit constant currency revenue growth and enhanced operating leverage expectations," CEO Dave Mowry reassured investors.

However, with Tornier shares still sporting a particularly lofty 40-plus price-to-cash flow multiple, I'd wait for an even wider margin of safety before buying into that optimism.