Shares in Ashtead surged on Wednesday after the equipment-rental firm reported a big jump in first-half profits and lifted its full-year expectations.The company said that underlying pre-tax profit jumped by 33% to a record £265.5m in the six months to 31 October.Pre-tax profits in the second quarter alone were up 33% year-on-year at £145.1m, around 8% ahead of analysts' expectations.Group revenues totalled £987.3m in the first half, up 23% on last year on a constant-currency basis, with strong growth from the larger US division, Sunbelt, as well as the UK arm, A-Plant."Our strong performance continued in November. With both divisions performing well and the benefit of weaker sterling, we now anticipate a full-year result ahead of our previous expectations," Ashtead said.The company lifted its interim dividend by 33% to 3p per share.The stock was up 6.8% at 1,150p by 08:33."Ashtead continues to demonstrate significant market share gain against a backdrop of recovering demand for non-resi construction," said analysts at Liberum.