From creating artificial limbs to aircraft parts, 3-D printing has been hailed as revolutionary, but investors are disagreeing with the hype and are ramping up their short positions as earnings in the sector have fallen short of expectations.
While 2013 burned short sellers of 3-D printing stocks, 2014 provided an "injection of reality", according to Markit.
Average short interest as a percentage of shares outstanding has risen to from 9.7 percent to 12.75 percent from the start of the year for the five major players, which include the New York-listed 3-D Systems and Nasdaq-listed Stratasys -- indicating that investors are already betting that stocks will fall.
"In 2013 3-D printing stocks were categorized by strong revenue growth, rising stock prices, and shorts running for the exit after experiencing agonizing losses," Markit said in a note.
"2014 provided an injection of reality. The average return of the five 3-D printing companies below was minus 29 percent while short interest levels varied from flat to surging in the case of Stratasys. Unsurprisingly, the insanely high valuations at the end of 2013 proved unsustainable."
A great deal of hype has surrounded 3-D printing over the past year with manufacturers in a wide variety of industries looking at ways to use the technology to drive down costs.