I'm deeply suspicious of anything calling itself an investment philosophy that's much more complex than "buy stocks trading for less than their intrinsic worth." But the truth of the matter is that there are some approaches that seem to correlate with better-than-average performance; one is to seek out market leaders in largely ignored industries.

Acuity Brands (NYSE:AYI), take a bow. Unless you're an architect, lighting engineer, or light bulb salesperson, I doubt you spend much time thinking about the lighting fixtures in offices, schools, and hospitals -- though this company is responsible for about one-fifth of them. Likewise in the world of janitorial supplies -- Acuity is No. 3 in a business that's sometimes all about taking care of numbers one and two.

Now, I liked this company back in October of 2005, and the stock has obligingly gone up about one-third since then. And this quarter's results don't suggest to me that the story has maxed out just yet. Sales were up nearly 9%, with roughly half of that coming from volume growth, and sales in the lighting business (about three-quarters of the total) were up more than 11%. Operating profits were also considerably higher this quarter, and year-to-date cash flow growth is tracking nicely.

And let's remember, this is in the absence of a pronounced upswing in non-residential construction. Sure, there are positive signs here and there from companies that all have fingers in the pie, like UnitedTechnologies (NYSE:UTX), Ingersoll-Rand (NYSE:IR), and Illinois Tool Works (NYSE:ITW), but nobody has come out just yet and said, "Non-residential is finally rocking."

My one concern about the company is probably a nitpick. Management said they expect unit growth in the lighting business to track market growth -- suggesting they're not gaining share. Now, I realize that the likes of Cooper (NYSE:CBE) and Genlyte (NASDAQ:GLYT) are not pushovers, but I usually like to see my market-leading companies still managing to gain unit share -- even if it has to come at the expense of the dozens of small-fry competitors.

As I said, that's probably more of a nitpick than a serious concern. Still, I'm a little less excited about the stock -- it's a good company in an obscure (but essential) industry, but the stock's nice run has left it fairly valued.

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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).