Selling expenses were kEUR 1,788 for the third quarter of 2015 compared to kEUR 1,090 in the third quarter of 2014. The increase of kEUR 698 was the result of our expanded global sales effort as we increased our international presence and attended more trade shows and fairs compared to the prior year period. In addition, there was an accrual for a bonus for the sales force amounting to kEUR 197 in the third quarter of 2015. In the prior year period, the company did not recognize an accrual for the sales force. Headcount increased from 23 as of September 30, 2014 to 39 employees as of September 30, 2015, which included employees from the acquisition of voxeljet UK during the fourth quarter of 2014.
Administrative expenses were kEUR 1,317 for the third quarter of 2015 compared to kEUR 1,077 in the third quarter of 2014. The increase of kEUR 240 was primarily due to increased headcount and consequently higher personnel expenses. This includes employees from the acquisition of our subsidiary in the UK during the fourth quarter of 2014. Headcount increased from 23 as of September 30, 2014 to 46 employees as of September 30, 2015.
Research and development (R&D) expenses increased to kEUR 1,685 in the third quarter of 2015 from kEUR 1,032 in the prior year period, as we continued to invest heavily in R&D with a number of active projects in various stages of development. Those investments are intended to strengthen our leadership in technology. Headcount increased from 35 as of September 30, 2014 to 58 employees as of September 30, 2015.
Other operating expenses in the third quarter of 2015 were kEUR 394 compared to kEUR 18 in the prior year period, mainly due to losses from foreign currency transactions.
Other operating income was kEUR 119 for the third quarter of 2015 compared to kEUR 155 in the third quarter of 2014. This mainly includes the recognition of income related to sale and lease back transactions.
Operating loss was kEUR 3,527 in the third quarter of 2015, compared to an operating loss of kEUR 1,664 in the prior year period. Our increased operating loss in the third quarter of 2015 was the result of an increase in our operating expenses, primarily caused by higher selling and research and development expenses and increased headcount related to the pursuit of our growth strategy and impairment charges.
Net loss for the third quarter of 2015 was kEUR 3,397, or EUR 0.91 per share as compared to net loss of kEUR 1,518, or EUR 0.41 per share, in the third quarter of 2014. This is based on a weighted average number of ordinary shares outstanding of 3.720 million during the third quarter of 2015 and 2014, respectively.
Based on a conversion rate of five American Depositary Shares (ADSs) per ordinary share, net loss was EUR 0.18 per ADS for the third quarter of 2015 compared to net loss of EUR 0.08 per ADS in the third quarter of 2014.
Nine months Ended September 30, 2015 Results
Revenues for the nine months ended September 30, 2015 increased by 71.1% to kEUR 15,783 compared to kEUR 9,225 in the prior year period.
Systems revenues were kEUR 6,211 for the first nine months of 2015 compared to kEUR 4,810 in last years period. The Company sold seven new and two used and refurbished 3D printers during the first nine months of 2015 compared to seven new 3D printers in the prior year period. Systems revenues represented 39.4% of total revenue for the nine months ended September 30, 2015 compared to 52.1% for the same period a year ago.
Services revenues were kEUR 9,572 for the nine months ended September 30, 2015 compared to kEUR 4,415 for the same period last year. This increase was mainly due to the revenue contribution from our subsidiaries voxeljet UK Ltd. (voxeljet UK, acquired in the fourth quarter 2014) and voxeljet America, Inc. (voxeljet America, which began printing on-demand parts in the first quarter of 2015). We also continued to benefit from the expansion of our service center in Germany (completed in April 2014), where Service revenues increased 35.3% compared to last years same period. In addition, last years temporary operating disruption of one VX4000 printer at our service center in Friedberg, Germany due to a technical issue resulted in less available capacity and negatively impacted gross margin in the third quarter of 2014.
Cost of sales for the nine months ended September 30, 2015 was kEUR 10,532, an increase of kEUR 4,644, or 78.9%, over cost of sales of kEUR 5,888 for the same period in 2014. For the nine months ended September 30, 2015, the cost of sales related to our Long Term Cash Incentive Plan (LTCIP), implemented effective January 1, 2013 was kEUR 399 compared to kEUR 174 for the same period last year. During the third quarter of 2015, the Company recognized an impairment charge of kEUR 309 on the digital library intangible asset at its voxeljet UK subsidiary, as well as a write-down of kEUR 26 on the raw materials at voxeljet UK.
Gross profit and gross margin for the nine months ended September 30, 2015 were kEUR 5,251 and 33.3%, respectively, compared to kEUR 3,337 and 36.2% in the prior year period.
Gross profit for our Systems segment increased to kEUR 1,846 for the
nine months ended September 30, 2015 from kEUR 1,494 in the same period
of 2014. The gross profit margin for this segment decreased to 29.7%
compared to 31.1% for the prior period primarily due to a less favorable
printer mix. In the first nine months of 2015, cost of sales related to
the LTCIP was kEUR 218 compared to kEUR 99 for the same period last year.