What happened

Contract 3D printer Proto Labs (PRLB -0.73%), which produces custom-made 3D-printed parts for prototyping and short-run production for its customers, failed to print the right kinds of numbers for its shareholders in this morning's fiscal Q4 2019 earnings report -- and is being punished for it. Shares were down 9.5% as of 10:50 a.m. EST on Thursday.

Heading into Q4, analysts had told investors to expect $0.63 per share in pro forma earnings from Proto Labs, and sales of just under $112 million. It barely achieved that earnings estimate, and just missed the sales target at $111.9 million.

Chalkboard drawing of arrow going down over the word DOWN

Image source: Getty Images.

So what

That may not sound like much of a miss. But after growing sales a bare 3% for all of 2019, Proto Labs ended the year on a weak note with a 0.8% decline in sales in Q4.

As for profits, the company may have met expectations by the malleable standard of pro forma earnings. But as calculated by generally accepted accounting principles (GAAP), earnings for the quarter were only $0.56 per share, diluted -- and down 21% year over year.

Now what

Perhaps worst of all, the company guided investors to expect even more underperformance in the current first quarter of fiscal 2020. Instead of the $0.67 per share (again, pro forma) that Wall Street is expecting, Proto Labs says it's more likely to earn somewhere between $0.50 and $0.58, a huge earnings miss. The company's expected sales of $111 million to $117 million, when taken at the midpoint, also appear likely to fall short of the $115.3 million analyst consensus.

In short, it's the prospect of Proto Labs following up one missed guidance quarter with a second that's scaring off investors today.