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.