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What happened

Shares of building-industry supplier NCI Building Systems Inc. (NYSE:NCS) fell as much as 12.3% on Friday after the company released earnings. As of 3 p.m. EST, shares were still down 9.9% on the day.

So what

Sales were up 4.5% to $480.3 million and net income was up 3.9% to $18.9 million, or $0.27 per share. Adjusted for one-time items, earnings were $0.28 per share; that fell three cents below expectations, which is what investors are reacting to today.

In fiscal 2017, management expects revenue to be between $1.75 billion and $1.85 billion, while EBITDA (earnings before interest, taxes, depreciation, and amortization) should be $175 million to $205 million. This indicates significant growth from $1.68 billion in revenue in fiscal 2016.

Now what

The market's first reaction is often to simply compare performance in a quarter to analyst expectations. But long-term investors should be looking at how the business is trending. And with growth in the residential market expected to be 3% to 6% next year, and NCI Building Systems' management expecting to gain market share, the future is getting brighter. Shares aren't cheap at 23 times earnings, but with sales on the rise, I think the sell-off in shares has been overdone.