|TRIVAGO N.V. filed this Form 20-F on 03/06/2018|
connection with our IPO, including consolidated U.S. GAAP financial statements and related audits. Other factors contributing to the increase included an increase in bad debt expense of €3.5 million, higher overhead costs due to increased headcount of €1.4 million, rent expense associated with the build-to-suit lease for our new corporate headquarters of €0.9 million and increased rent of €0.5 million. Personnel costs for the year ended December 31, 2016 increased by €4.4 million, or 81.5%, compared to the year ended December 31, 2015, primarily driven by an increase in headcount from 121 employees as of December 31, 2015 to 187 employees as of December 31, 2016. Further, we incurred increased related party shared service costs of €1.4 million, or 50.0%, primarily attributable to an increase in legal, tax, treasury, audit and corporate reorganization that was incurred by Expedia on our behalf of €0.8 million and an increase in IPO and corporate reorganization costs of €0.6 million pushed down by Expedia.
Amortization of intangible assets
Amortization of intangible assets was €3.2 million in the year ended December 31, 2017, and €13.9 million and €30.0 million in the years ended December 31, 2016 and December 31, 2015, respectively. The decreases of €10.7 million and €16.1 million for the years ended December 31, 2017 and December 31, 2016, respectively, are due to certain technology assets that were fully amortized during the first quarters of 2017 and 2016, respectively. The amortization costs relate predominantly to intangible assets recognized by Expedia upon the acquisition of a majority stake in trivago GmbH in 2013. The financial statements reflect Expedia’s basis of accounting due to this change in control in 2013.
Our operating loss was €20.4 million for the year ended December 31, 2017 compared to an operating loss of €44.4 million for the year ended December 31, 2016. We have seen our operating loss decrease when compared to the year ended December 31, 2016. Selling and marketing expenses reflected our inability to pull back planned TV advertising spend due to commitments in some markets. Our operating loss was impacted by a slight increase in technology and content costs and a decrease in general and administrative expenses, including lower share-based compensation primarily driven by fluctuations in the fair value accounting treatment of awards which were classified as liability awards in the prior periods and lower amortization of intangible assets.
Our operating loss was €44.4 million for the year ended December 31, 2016 compared to an operating loss of €47.9 million for the year ended December 31, 2015. The operating loss decreased primarily due to higher growth in revenue combined with a lower amortization of intangible assets, partially offset by increased costs and expenses, particularly relating to share-based compensation primarily driven by fluctuations in the fair value accounting treatment of liability classified awards granted in prior periods.
Other, net is primarily comprised of a foreign exchange loss of €1.0 million and gains of €0.0 million and €0.1 million for the years ended December 31, 2015, 2016 and 2017, respectively, as well as income from ADSs offset by custodial fees related to ADSs of €0.3 million for the year ended December 31, 2017, other expenses of €0.2 million for the year ended December 31, 2016 and the reversal of an indemnification asset related to an uncertain tax position and the related interest of €1.7 million for the year ended December 31, 2015.