6. Operating costs

Operating result has been calculated after charging (–) / crediting:

Research and development expenditure

The following table summarizes research and development expenditure for the years ended 31 December 2015 and 2014.

R&D expenditure increased by €18.6 million, or 17%, to €129.7 million for the year ended 31 December 2015, from €111.1 million for the year ended 31 December 2014. This increase was principally due to:

• Increased R&D personnel costs of €4.8 million, or 16%, from €31.0 million for the year ended 31 December 2014 to €35.9 million for the year ended 31 December 2015, which was explained by an enlarged workforce, higher warrant costs and a higher provision for short term and long term management bonus, mainly as a result of the evolution of our share price change relative to the Next Biotech Index on Euronext
• Increased subcontracting costs of €11.6 million, or 21%, from €54.3 million for the year ended 31 December 2014 to €65.9 million for the year ended 31 December 2015. This cost increase was mainly driven by increased subcontracting costs of €8.4 million for the CF collaboration with AbbVie and to a lesser extent by the increase of €4.2 million in subcontracting costs for our other partnered and internal programs
• Intensified use of lab consumables was the main driver of the increase in disposables, lab fees and premises costs of €1.9 million, or 11%, from €16.8 million for the year ended 31 December 2014 to €18.7 million for the year ended 31 December 2015
• Other operating expenses slightly increased by €0.3 million, or 3%, from €8.9 million for the year ended 31 December 2014 to €9.3 million for the year ended 31 December 2015

The table below summarizes our research and development expenditure for the years ended 31 December 2015 and 2014, broken down by research and development expenses under alliance and own funded research and development expenses.

We tracked all research and development expenditures against detailed budgets and allocated them by individual project.

Research and development expenditure under alliance increased by €4.5 million, or 6%, from €76.3 million for the year ended 31 December 2014 to €80.8 million for the year ended 31 December 2015, mainly due to our CF program in collaboration with AbbVie. We also increased our investments in our own funded portfolio by €14.1 million, or 40%, from €34.8 million for the year ended 31 December 2014 to €48.9 million for the year ended 31 December 2015, primarily because GLPG1205 and GLPG1690 programs became own funded.

General and administrative expenses

The following table summarizes the general and administrative expenses for the years ended 31 December 2015 and 2014.

General and administrative expenses amounted to €13.9 million for the year ended 31 December 2014 and increased by €5.2 million, or 38%, to €19.1 million for the year ended 31 December 2015. This increase was principally due to personnel costs and directors fees, which increased by €4.6 million, or 58%, from €8.1 million for the year ended 31 December 2014 to €12.7 million for the year ended 31 December 2015, resulting from various effects, such as increased costs of share-based payments plans (warrant plans) and increased provision for short and long term management bonus, mainly as a result of the evolution of our share price change relative to the Next Biotech Index on Euronext. In addition, other operating expenses increased by €0.6 million, or 10%, from €5.8 million for the year ended 31 December 2014 to €6.4 million for the year ended 31 December 2015, mainly due to higher professional fees.

Sales and marketing expenses

The following table summarizes the sales and marketing expenses for the years ended 31 December 2015 and 2014.

Sales and marketing expenses increased by €0.2 million, or 19%, from €1.0 million for the year ended 31 December 2014 to €1.2 million for the year ended 31 December 2015.

Restructuring costs

The restructuring and integration costs amounted to €0.7 million for the year ended 31 December 2014 and were entirely related to workforce reductions within certain of the R&D operations.