The central idea of value investing, or at least my type of value investing, is to wait for great companies to become available at great (or at least good) prices. What, then, should we make of the nosedive in Forward Air's (NASDAQ:FWRD) shares since this specialized ground carrier reported earnings?

Though backward-looking, the results themselves weren't terribly problematic. Second-quarter revenue rose 12% and operating income rose 18%, as management continues to run an efficient business model. But if those growth rates sound lower to you than those of recent quarters, you're right. The company passed the anniversary of the XGS acquisition last year, and growth in just the month of June (the anniversary was May 31) was on the order of 8%.

That's only part of what has some people nervous, though. Volume growth was solid in the second quarter (up about 4% on an average pounds-per-week basis), but management talked openly about rivals doing "silly deals" to gain volume, which may force Forward Air to ease up on its own pricing to preserve its revenue base. But remember that Forward Air is a major player here; it's often difficult for rivals to keep any business they take from Forward, since they can't always offer equivalent levels of service.

On top of all that, this just isn't a great time to be in the cargo transportation business. The charts of UPS (NYSE:UPS) and Forward Air are nearly identical, and companies ranging from truckers like J.B. Hunt (NASDAQ:JBHT) to Old Dominion (NASDAQ:ODFL) and rail operators like CSX (NYSE:CSX) have seen weakness in their stocks as well. Everybody is concerned that higher interest rates will start to choke off economic activity, even as fuel prices remain stubbornly high, exacerbating the situation.

Forward Air is at long last trading at a double-digit discount to my estimate of fair value. If it falls just a little further, it'll be increasingly hard to ignore the opportunity here. I realize that we may be heading for softer economic conditions, but Forward Air has great market share in a very good business. Over time, that usually trumps the ups and downs of the business cycle.

Further Foolishness, ready for delivery:

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).