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 Green Mountain Coffee Roasters (Nasdaq: GMCR), the company behind the Keurig single-serve brewers, tasted particularly bitter to investors for part of the day today, as hedge-fund manager Whitney Tilson made some concerning remarks.

So what: Currently under examination by the Securities and Exchange Commission, Green Mountain has become a prime target for short sellers because of accounting questions and the stock's sky-high valuation. Today in an interview on CNBC, referring to the SEC investigation and the potential that it will uncover accounting fraud, T2 Partners co-founder Tilson said, "We think they are going to find something."

Now what: The fact that Green Mountain shares plunged so drastically and then recovered shows just how skittish investors are about the stock right now. Tilson -- along with Greenlight Capital's David Einhorn -- is a current "short" on Green Mountain, meaning that he has borrowed shares to bet against the stock. Just as bullish investors have their agendas when they talk stocks, bears often have money at stake as well, so it's best to view Tilson's comments in that light.

But is he right? This Fool isn't touching Green Mountain shares because they're simply too darn expensive. As far as the accounting goes, though, investors shouldn't be fleeing simply because of Tilson's remarks. However, his concerns are a good reason for bulls to take a closer look to make sure they're not sitting on a time bomb.

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