Shares in engineering construction firm Monadelphous have tumbled despite the group posting a record first half profit.
The company's net profit for the six months to December 31 grew by 38 per cent to $79.1 million, compared with $57.5 million during the corresponding period in 2011.
Managing director Rob Velletri said unprecedented engineering construction activity in the iron ore and liquefied natural gas sectors drove the profit surge.
However, Mr Velletri admitted the high level of activity would be unlikely to continue into 2013/14 as revenue growth slowed.
"There's been a big surge in the business in the last two years," he told a briefing in Perth.
"We're just being realistic ... we don't see significant growth again the following year.
"We need to make sure we're in shape for revenue growth beyond this year."
Shares in Monadelphous Group finished $1.68, or six per cent weaker, at $26.17 on Tuesday.
Mr Velletri forecast a 35 per cent rise in revenue over the full financial year, rising by 47 per cent in the first half to $1.3 billion.
Two-thirds of sales revenue came from the firm's engineering construction division, with major projects tied to Rio Tinto's Cape Lambert iron ore and Kestrel coal mines in Western Australia and Queensland, along with Gina Rinehart's Hope Downs iron ore venture.
Mr Velletri said that uncertainty remained about the rate of new project approvals as customers reassessed their capital expenditure plans.
"We certainly see 2013/14 as a year of consolidation where revenue growth will be challenging," he said.
Mr Velletri said project delays and a slowdown in new major project approvals would be likely to reduce medium-term opportunities.
IG Markets market strategist Evan Lucas said falling discretionary spending from the big miners like BHP Billiton and Rio Tinto would affect the business, with this concern hitting the share price.
"One thing I was surprised by is how hard Monadelphous has been hit," he told AAP.
"Monadelphous produced an okay result, it was fairly much in line, but (its shares) are off considering that they are seeing guidance being a little bit squeezed and the pipeline a little bit choppy."
Monadelphous declared a fully franked interim dividend of 62 cents per share, up from 50 cents in the previous corresponding period.