(ShareCast News) - Share in Regus jumped over 5% earlier on Tuesday, after the office space provider more than doubled its interim pre-tax profit.In the six months to the end of June, the group saw its pre-tax profit jump for £31m to £79.1m, on the back of improvement in its return on investment, which climbed from 20.9% to 23.1%.Revenue rose 16.4% year-on-year to £937.0m, boosted by the acquisitions of 231 new locations at a net capital investment of £120m."Our focus on greater operational rigour and efficiency has continued to drive economies of scale and a further reduction in overheads as a percentage of revenue," said group chief executive Mark Dixon."Current trading is in line with management expectations and the board remains confident in our prospects for 2015 and beyond as we continue to enhance shareholder value."Regus shares were up 5.10% to 261.80 at 0822 BST on Tuesday.