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 aerospace supplier HEICO Corp. (NYSE: HEI) -- motto: "No, not the company with the talking lizard" -- popped 11% this morning.

So what: Second-quarter earnings were the catalyst, with profits up 34% year over year, exceeding Wall Street estimates and leading to a bump in guidance for the year.

Now what: Good news? No doubt. And surprising news, too. Traders had placed short bets against more than 30% of the company's float going into earnings. I suspect there's quite a bit of short covering going on right now, and that this is contributing to the shares' surge to an all-time high.

Once the covering ends, HEICO bears will doubtless tell us that at 35 times earnings, the stock's an even safer short-bet now. Don't believe it. According to its cash flow statement, HEICO generated more than $104 million in free cash flow over the past 12 months -- 61% better than reported as "net income" under GAAP. While the resulting price-to-free cash flow ratio of 22 looks a little pricey relative to consensus growth prospects, this stock's not nearly as expensive as it looks. And not nearly as safe a short as its critics believe.

Bears vs. bulls -- who will carry the day? Add HEICO to your watchlist and find out.

Fool contributor Rich Smith holds no position in any company mentioned. Click here to see his holdings and a short bio. Try any of our Foolish newsletter services free for 30 days. 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.