Shares of 3D printer companies continued a second day of declines Friday, after a critical report Thursday by a firm that specializes in short sales.
In midday trading in the stock market today, 3D printer leader 3D Systems (DDD) was down more than 5%, after falling 2.9% on Thursday.
Shares of Stratasys (SSYS) were down more than 2% after falling 4.6% on Thursday. Recent IPO ExOne (XONE) was down more than 4%. It fell 3% Thursday.
Proto Labs (PRLB), which unlike the three companies named above does not make 3D printers but instead provides related services, was down 4.5% after an 8.2% slide Thursday.
The stocks seemed to start falling on Thursday after analyst Andrew Left, executive editor of Citron Research, said 3D Systems is a "bubble stock.
"We are not claiming that direct digital manufacturing has no place in the industrial landscape and that it won't grow incrementally as new technology enables new applications," he wrote. "We simply observe that appearances have become completely unhinged from reality when it comes to the mania created in so-called 3D printing stocks, and 3D Systems in particular.
Citron often makes short sales, a bet that a stock will fall.
3D printer stocks have been hot the past year. In the past 12 months, 3D Systems has tripled. The company has posted double-digit revenue growth in each of the last four quarters, along with double-digit profit growth in the past three quarters. It's slated to report Q4 results on Feb. 25.
Shares of Stratasys are up about 85% the past year. It has posted nine straight quarters of double-digit growth in revenue and profit. It reports its fourth-quarter earnings on March 4.
ExOne made its debut as a publicly traded company on Feb. 7 with a strong initial public offering. Shares of ExOne rose 47% to 26.52 on its first day, about where it trades today. It sold 5.3 million shares at $18 each, raising more than $95 million, as IBD reported.
Proto Labs made its IPO last Feb. 24, pricing at $16 a share. It peaked Wednesday near 54 after reporting better-than-expected results.
President Obama, in his State of the Union speech Tuesday, spoke about job creation in the technology sector. In the speech he mentioned 3D technology, saying "it has the potential to revolutionize the way we make almost everything," as IBD reported. Shares of 3D Systems, Stratasys and ExOne all rose the following day, Wednesday, before starting to slide on Thursday.