BBA Aviation (LON:BBA) saw shares fall over 13 percent on Wednesday, after exceptional costs weighed on profits in the first half of the year.

Pretax profit fell 11 percent to $76.2 million, despite a 14 percent increase in revenue to over $1 billion. The aviation support services group cited a high level of exceptional charges as the reason for the fall in profits, adding that underlying pretax profit rose 3.3 percent to $180.5 million.

“With the first full six months contribution from the network agreements, Signature is making encouraging progress despite the softer than expected US B&GA market,” the company said.

“The board is confident of modest growth in 2018, through continued outperformance against a soft US B&GA market backdrop and Ontic continues to have a strong pipeline of growth opportunities”.

The interim dividend was increased by 5 percent to $0.04. Shares in BBA Aviation are currently trading down 13.31 percent at 303.40 (1124GMT).