What happened

Shares of 3D printer-maker 3D Systems (NYSE:DDD) carried last week's post-earnings-news surge into the new week this morning. 3D shares rose as much as 12% in early trading, on top of the 21% worth of gains the company already reaped through the close of trading Friday -- and they were still up 9.2% as of 3:30 p.m. ET.

So what

Just to be clear, last week's rally was sparked by earnings news, but not by an official earnings report. All 3D management actually released was a "preliminary" report informing investors that Q4 sales were likely to rise 6% to 7% year over year to between $176 million and $178 million -- with a GAAP loss for the quarter of between $0.08 and $0.10 per share.

Still, those numbers looked likely to beat Wall Street analysts' estimates, and it seems that was good enough for investors. It also appears to have pleased the analysts themselves: This morning, investment banker Susquehanna Securities raised its price target for 3D stock to $10 a share.

Stick figure explaining why red arrow is going up

Why is 3D stock up again? There appears to be only one reason. Image source: Getty Images.

Now what

Whether that shift in price target was the reason 3D shares kept rising today, or whether they're simply coasting along on last week's momentum, is not clear. What is clear is that even Susquehanna's new and improved price target values 3D stock at 20% less than what it costs today.

As soon as investors realize that, it's possible we could see 3D's gains over the past few days begin to evaporate.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.