Shares in Ashtead (LON:AHT) sank 14% after the plant hire group said headwinds from low oil prices were set to continue in the fourth quarter.
Ashtead, which owns A-Plant in the UK and Sunbelt in the US, increased third quarter underlying earnings by 18% to £277.4mln on a 14% rise in rental revenue to £546.9mln.
Underlying pre-tax profits rose 20% to £482mln in the nine months to January 31 against the same time a year ago.
Excluding the impact of the downturn in the oil & gas industry, good yield increases from greenfield hire outlets and bolt-on acquisitions helped to boost like-for-like yields by 2%.
The company opened 51 greenfield outlets during the nine months to January 31 against the same period last year and spent US$73mln on bolt-ons.
But the group said the adverse impact of lower oil & gas investment more than offset that, resulting in overall yield being flat.
"Total rental only revenue growth was 20% in strong end markets, despite the slow-down in oil and gas markets that provided a headwind which will continue in the fourth quarter," the group said.
Ashtead outlined plans to cut spending on replacement equipment from £1.2bn this year to between £700mln and £1bn next year.
Hargreaves Lansdown investment analyst Charlie Huggins also blamed the share price fall on worries about a slowdown in the US, where the group makes most of its profit.
He said: "Ashtead’s plans to cut back capital expenditure and reduce leverage are sensible in this context, but do little to allay investors’ concerns of tougher times ahead."
The group's shares were near the top of the fallers in mid-morning London trading, dropping 124.5p, or 13.5%, to 799.5p.
Chief executive Geoff Drabble stayed upbeat, saying it continued to expect encouraging growth opportunities and double-digit fleet growth in the US in 2016/17.
"With both divisions performing well, strong end markets and our strategy clearly working, we expect full year results to be in line with our expectations and the board looks forward to the medium term with confidence," he said.