What's happening: Shares of ExOne (NASDAQ:XONE) were down nearly 12% today following the release of its second-quarter earnings after the market closed yesterday. The results fell below Wall Street expectations.

Why it's happening: In the second quarter, ExOne's revenue decreased by 24% year over year to $8.5 million, translating to a $0.48 loss per share. Wall Street was anticipating ExOne would generate $11.1 million in sales and lose $0.26 per share.

ExOne also lowered its full-year gross margin target from 36%-40% to 30%-34%, citing higher-than-expected costs and inefficiencies getting its newer production service centers and management system up and running. However, the company maintained its full-year outlook of generating between $58 million and $66 million in sales this year.

ExOne's 3D printer sales fell by 60% year over year to 2.4% million, partly because the company only recognized revenue from seven of the 12 3D printers it shipped during the quarter. It came to light last quarter that there could be a several quarters of delay between when ExOne ships a 3D printer and books the sale as top-line revenue. ExOne's accounting rules are such that it only recognizes revenue after a 3D printer is accepted by a customer, meaning the printer has been installed, made operational, and the customer has been adequately trained.

On the 3D printing services front, ExOne's non-machine revenue increased by 16% year over year and 7% sequentially to a record $6.1 million, suggesting that its binder jetting technology continues to gain acceptance across the industry.

ExOne ended the second quarter with $24.8 million in cash on its balance sheet and $2.3 million in debt.