Renishaw surged by almost a fifth on Wednesday after the precision engineer posted a sharp rise in half year pre-tax profit and upped its dividend following a surge in demand from Asia and metrology products.Pre-tax profit surged to £35.5m in the six months ended 31 December 2010 from £7.1m the same time a year earlier. Revenue increased to £129.3m during the period from £73.8m before. Heritage Oil, however, is heading the opposite way after discovering large quantities of gas at its Miran West-2 well, rather than oil like investors were hoping for. Even though Heritage uncovered the largest gas field to be discovered in Iraq for more than 30 years, "we think this is a disappointing result for Heritage," says Matrix analyst Vugar Aliyev.Sector peer Afren, which is focused in Africa, is also lower after reporting "shockingly weak production numbers", according to finnCap.Bermuda-based specialist insurer Hiscox is edging higher despite estimating net claims linked to Britain's coldest winter on record will hit £16m. The firm's UK household business is said to be on track to make a "healthy profit" and claims for the Chilean earthquake and Windstorm Xynthia have actually been revised down.FTSE 250 - RisersRenishaw (RSW) 1,573.00p +17.83%Premier Foods (PFD) 22.45p +8.56%BTG (BGC) 249.00p +7.14%Spirent Communications (SPT) 140.10p +7.03%Cookson Group (CKSN) 669.50p +5.85%Morgan Crucible Co (MGCR) 270.00p +5.84%Howden Joinery Group (HWDN) 118.20p +5.44%ITE Group (ITE) 230.70p +4.77%Millennium & Copthorne Hotels (MLC) 582.00p +4.39%Halma (HLMA) 335.60p +4.35%FTSE 250 - FallersHeritage Oil (HOIL) 342.90p -21.46%Ocado Group (OCDO) 218.00p -4.39%IG Group Holdings (IGG) 457.90p -2.70%F&C Asset Management (FCAM) 87.70p -2.39%Hansen Transmissions International NV (DI) (HSN) 57.00p -2.31%SVG Capital (SVI) 231.50p -2.16%Brown (N.) Group (BWNG) 290.00p -2.13%Drax Group (DRX) 390.40p -1.98%Afren (AFR) 145.80p -1.88%Carpetright (CPR) 762.00p -1.80%